fix the provided openapi spec

a lot of things marked required actually aren't

27 files changed, 212 insertions, 236 deletions

diff --git a/data/spec-v1-swagger.json b/data/spec-v1-swagger.json
index 6b11782..fea1c53 100644
--- a/data/spec-v1-swagger.json
+++ b/data/spec-v1-swagger.json
@@ -1479,7 +1479,7 @@
       "properties": {
         "data": {
           "type": "object",
-          "required": ["budgets", "default_budget"],
+          "required": ["budgets"],
           "properties": {
             "budgets": {
               "type": "array",
@@ -1694,7 +1694,6 @@
         "type",
         "on_budget",
         "closed",
-        "note",
         "balance",
         "cleared_balance",
         "uncleared_balance",
@@ -1849,15 +1848,10 @@
         "category_group_id",
         "name",
         "hidden",
-        "note",
         "budgeted",
         "activity",
         "balance",
-        "goal_type",
-        "goal_creation_month",
         "goal_target",
-        "goal_target_month",
-        "goal_percentage_complete",
         "deleted"
       ],
       "properties": {
@@ -1990,7 +1984,7 @@
     },
     "Payee": {
       "type": "object",
-      "required": ["id", "name", "transfer_account_id", "deleted"],
+      "required": ["id", "name", "deleted"],
       "properties": {
         "id": {
           "type": "string",
@@ -2251,17 +2245,9 @@
         "id",
         "date",
         "amount",
-        "memo",
         "cleared",
         "approved",
-        "flag_color",
         "account_id",
-        "payee_id",
-        "category_id",
-        "transfer_account_id",
-        "transfer_transaction_id",
-        "matched_transaction_id",
-        "import_id",
         "deleted"
       ],
       "properties": {
@@ -2460,10 +2446,6 @@
         "id",
         "transaction_id",
         "amount",
-        "memo",
-        "payee_id",
-        "category_id",
-        "transfer_account_id",
         "deleted"
       ],
       "properties": {
@@ -2546,12 +2528,9 @@
         "date_next",
         "frequency",
         "amount",
-        "memo",
         "flag_color",
         "account_id",
-        "payee_id",
         "category_id",
-        "transfer_account_id",
         "deleted"
       ],
       "properties": {
@@ -2658,10 +2637,7 @@
         "id",
         "scheduled_transaction_id",
         "amount",
-        "memo",
-        "payee_id",
         "category_id",
-        "transfer_account_id",
         "deleted"
       ],
       "properties": {
@@ -2740,7 +2716,7 @@
     },
     "MonthSummary": {
       "type": "object",
-      "required": ["month", "note", "income", "budgeted", "activity", "to_be_budgeted", "age_of_money", "deleted"],
+      "required": ["month", "income", "budgeted", "activity", "to_be_budgeted", "deleted"],
       "properties": {
         "month": {
           "type": "string",
diff --git a/ynab-api/docs/Account.md b/ynab-api/docs/Account.md
index adeab71..265294b 100644
--- a/ynab-api/docs/Account.md
+++ b/ynab-api/docs/Account.md
@@ -9,7 +9,7 @@ Name | Type | Description | Notes
 **_type** | **String** | The type of account. Note: payPal, merchantAccount, investmentAccount, and mortgage types have been deprecated and will be removed in the future. | 
 **on_budget** | **bool** | Whether this account is on budget or not | 
 **closed** | **bool** | Whether this account is closed or not | 
-**note** | **String** |  | 
+**note** | **String** |  | [optional] 
 **balance** | **i64** | The current balance of the account in milliunits format | 
 **cleared_balance** | **i64** | The current cleared balance of the account in milliunits format | 
 **uncleared_balance** | **i64** | The current uncleared balance of the account in milliunits format | 
diff --git a/ynab-api/docs/BudgetSummaryResponseData.md b/ynab-api/docs/BudgetSummaryResponseData.md
index 6adce43..2836bfa 100644
--- a/ynab-api/docs/BudgetSummaryResponseData.md
+++ b/ynab-api/docs/BudgetSummaryResponseData.md
@@ -5,7 +5,7 @@
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **budgets** | [**Vec<::models::BudgetSummary>**](BudgetSummary.md) |  | 
-**default_budget** | [***::models::BudgetSummary**](BudgetSummary.md) |  | 
+**default_budget** | [***::models::BudgetSummary**](BudgetSummary.md) |  | [optional] 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 
diff --git a/ynab-api/docs/Category.md b/ynab-api/docs/Category.md
index 2afbe63..217979b 100644
--- a/ynab-api/docs/Category.md
+++ b/ynab-api/docs/Category.md
@@ -9,15 +9,15 @@ Name | Type | Description | Notes
 **name** | **String** |  | 
 **hidden** | **bool** | Whether or not the category is hidden | 
 **original_category_group_id** | **String** | If category is hidden this is the id of the category group it originally belonged to before it was hidden. | [optional] 
-**note** | **String** |  | 
+**note** | **String** |  | [optional] 
 **budgeted** | **i64** | Budgeted amount in milliunits format | 
 **activity** | **i64** | Activity amount in milliunits format | 
 **balance** | **i64** | Balance in milliunits format | 
-**goal_type** | **String** | The type of goal, if the cagegory has a goal (TB=Target Category Balance, TBD=Target Category Balance by Date, MF=Monthly Funding) | 
-**goal_creation_month** | [***String**](string.md) | The month a goal was created | 
+**goal_type** | **String** | The type of goal, if the cagegory has a goal (TB=Target Category Balance, TBD=Target Category Balance by Date, MF=Monthly Funding) | [optional] 
+**goal_creation_month** | [***String**](string.md) | The month a goal was created | [optional] 
 **goal_target** | **i64** | The goal target amount in milliunits | 
-**goal_target_month** | [***String**](string.md) | If the goal type is 'TBD' (Target Category Balance by Date), this is the target month for the goal to be completed | 
-**goal_percentage_complete** | **i32** | The percentage completion of the goal | 
+**goal_target_month** | [***String**](string.md) | If the goal type is 'TBD' (Target Category Balance by Date), this is the target month for the goal to be completed | [optional] 
+**goal_percentage_complete** | **i32** | The percentage completion of the goal | [optional] 
 **deleted** | **bool** | Whether or not the category has been deleted.  Deleted categories will only be included in delta requests. | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
diff --git a/ynab-api/docs/HybridTransaction.md b/ynab-api/docs/HybridTransaction.md
index 8c88165..69c0a4e 100644
--- a/ynab-api/docs/HybridTransaction.md
+++ b/ynab-api/docs/HybridTransaction.md
@@ -7,17 +7,17 @@ Name | Type | Description | Notes
 **id** | **String** |  | 
 **date** | [***String**](string.md) | The transaction date in ISO format (e.g. 2016-12-01) | 
 **amount** | **i64** | The transaction amount in milliunits format | 
-**memo** | **String** |  | 
+**memo** | **String** |  | [optional] 
 **cleared** | **String** | The cleared status of the transaction | 
 **approved** | **bool** | Whether or not the transaction is approved | 
-**flag_color** | **String** | The transaction flag | 
+**flag_color** | **String** | The transaction flag | [optional] 
 **account_id** | **String** |  | 
-**payee_id** | **String** |  | 
-**category_id** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer transaction, the account to which it transfers | 
-**transfer_transaction_id** | **String** | If a transfer transaction, the id of transaction on the other side of the transfer | 
-**matched_transaction_id** | **String** | If transaction is matched, the id of the matched transaction | 
-**import_id** | **String** | If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'. | 
+**payee_id** | **String** |  | [optional] 
+**category_id** | **String** |  | [optional] 
+**transfer_account_id** | **String** | If a transfer transaction, the account to which it transfers | [optional] 
+**transfer_transaction_id** | **String** | If a transfer transaction, the id of transaction on the other side of the transfer | [optional] 
+**matched_transaction_id** | **String** | If transaction is matched, the id of the matched transaction | [optional] 
+**import_id** | **String** | If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'. | [optional] 
 **deleted** | **bool** | Whether or not the transaction has been deleted.  Deleted transactions will only be included in delta requests. | 
 **_type** | **String** | Whether the hybrid transaction represents a regular transaction or a subtransaction | 
 **parent_transaction_id** | **String** | For subtransaction types, this is the id of the pararent transaction.  For transaction types, this id will be always be null. | 
diff --git a/ynab-api/docs/MonthDetail.md b/ynab-api/docs/MonthDetail.md
index d1fc13a..1d7a22b 100644
--- a/ynab-api/docs/MonthDetail.md
+++ b/ynab-api/docs/MonthDetail.md
@@ -5,12 +5,12 @@
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **month** | [***String**](string.md) |  | 
-**note** | **String** |  | 
+**note** | **String** |  | [optional] 
 **income** | **i64** | The total amount in transactions categorized to 'Inflow: To be Budgeted' in the month | 
 **budgeted** | **i64** | The total amount budgeted in the month | 
 **activity** | **i64** | The total amount in transactions in the month, excluding those categorized to 'Inflow: To be Budgeted' | 
 **to_be_budgeted** | **i64** | The available amount for 'To be Budgeted' | 
-**age_of_money** | **i32** | The Age of Money as of the month | 
+**age_of_money** | **i32** | The Age of Money as of the month | [optional] 
 **deleted** | **bool** | Whether or not the month has been deleted.  Deleted months will only be included in delta requests. | 
 **categories** | [**Vec<::models::Category>**](Category.md) | The budget month categories.  Amounts (budgeted, activity, balance, etc.) are specific to the {month} parameter specified. | 
 
diff --git a/ynab-api/docs/MonthSummary.md b/ynab-api/docs/MonthSummary.md
index e48e3a4..a78cbfc 100644
--- a/ynab-api/docs/MonthSummary.md
+++ b/ynab-api/docs/MonthSummary.md
@@ -5,12 +5,12 @@
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **month** | [***String**](string.md) |  | 
-**note** | **String** |  | 
+**note** | **String** |  | [optional] 
 **income** | **i64** | The total amount in transactions categorized to 'Inflow: To be Budgeted' in the month | 
 **budgeted** | **i64** | The total amount budgeted in the month | 
 **activity** | **i64** | The total amount in transactions in the month, excluding those categorized to 'Inflow: To be Budgeted' | 
 **to_be_budgeted** | **i64** | The available amount for 'To be Budgeted' | 
-**age_of_money** | **i32** | The Age of Money as of the month | 
+**age_of_money** | **i32** | The Age of Money as of the month | [optional] 
 **deleted** | **bool** | Whether or not the month has been deleted.  Deleted months will only be included in delta requests. | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
diff --git a/ynab-api/docs/Payee.md b/ynab-api/docs/Payee.md
index a52f0f9..ff886e6 100644
--- a/ynab-api/docs/Payee.md
+++ b/ynab-api/docs/Payee.md
@@ -6,7 +6,7 @@ Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **id** | **String** |  | 
 **name** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer payee, the account_id to which this payee transfers to | 
+**transfer_account_id** | **String** | If a transfer payee, the account_id to which this payee transfers to | [optional] 
 **deleted** | **bool** | Whether or not the payee has been deleted.  Deleted payees will only be included in delta requests. | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
diff --git a/ynab-api/docs/ScheduledSubTransaction.md b/ynab-api/docs/ScheduledSubTransaction.md
index 377c31f..6178bab 100644
--- a/ynab-api/docs/ScheduledSubTransaction.md
+++ b/ynab-api/docs/ScheduledSubTransaction.md
@@ -7,10 +7,10 @@ Name | Type | Description | Notes
 **id** | **String** |  | 
 **scheduled_transaction_id** | **String** |  | 
 **amount** | **i64** | The scheduled subtransaction amount in milliunits format | 
-**memo** | **String** |  | 
-**payee_id** | **String** |  | 
+**memo** | **String** |  | [optional] 
+**payee_id** | **String** |  | [optional] 
 **category_id** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer, the account_id which the scheduled subtransaction transfers to | 
+**transfer_account_id** | **String** | If a transfer, the account_id which the scheduled subtransaction transfers to | [optional] 
 **deleted** | **bool** | Whether or not the scheduled subtransaction has been deleted.  Deleted scheduled subtransactions will only be included in delta requests. | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
diff --git a/ynab-api/docs/ScheduledTransactionDetail.md b/ynab-api/docs/ScheduledTransactionDetail.md
index b140d03..5f45c7e 100644
--- a/ynab-api/docs/ScheduledTransactionDetail.md
+++ b/ynab-api/docs/ScheduledTransactionDetail.md
@@ -9,12 +9,12 @@ Name | Type | Description | Notes
 **date_next** | [***String**](string.md) | The next date for which the Scheduled Transaction is scheduled. | 
 **frequency** | **String** |  | 
 **amount** | **i64** | The scheduled transaction amount in milliunits format | 
-**memo** | **String** |  | 
+**memo** | **String** |  | [optional] 
 **flag_color** | **String** | The scheduled transaction flag | 
 **account_id** | **String** |  | 
-**payee_id** | **String** |  | 
+**payee_id** | **String** |  | [optional] 
 **category_id** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer, the account_id which the scheduled transaction transfers to | 
+**transfer_account_id** | **String** | If a transfer, the account_id which the scheduled transaction transfers to | [optional] 
 **deleted** | **bool** | Whether or not the scheduled transaction has been deleted.  Deleted scheduled transactions will only be included in delta requests. | 
 **account_name** | **String** |  | 
 **payee_name** | **String** |  | 
diff --git a/ynab-api/docs/ScheduledTransactionSummary.md b/ynab-api/docs/ScheduledTransactionSummary.md
index e66c915..4b248b0 100644
--- a/ynab-api/docs/ScheduledTransactionSummary.md
+++ b/ynab-api/docs/ScheduledTransactionSummary.md
@@ -9,12 +9,12 @@ Name | Type | Description | Notes
 **date_next** | [***String**](string.md) | The next date for which the Scheduled Transaction is scheduled. | 
 **frequency** | **String** |  | 
 **amount** | **i64** | The scheduled transaction amount in milliunits format | 
-**memo** | **String** |  | 
+**memo** | **String** |  | [optional] 
 **flag_color** | **String** | The scheduled transaction flag | 
 **account_id** | **String** |  | 
-**payee_id** | **String** |  | 
+**payee_id** | **String** |  | [optional] 
 **category_id** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer, the account_id which the scheduled transaction transfers to | 
+**transfer_account_id** | **String** | If a transfer, the account_id which the scheduled transaction transfers to | [optional] 
 **deleted** | **bool** | Whether or not the scheduled transaction has been deleted.  Deleted scheduled transactions will only be included in delta requests. | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
diff --git a/ynab-api/docs/SubTransaction.md b/ynab-api/docs/SubTransaction.md
index 9e48239..77bad7f 100644
--- a/ynab-api/docs/SubTransaction.md
+++ b/ynab-api/docs/SubTransaction.md
@@ -7,10 +7,10 @@ Name | Type | Description | Notes
 **id** | **String** |  | 
 **transaction_id** | **String** |  | 
 **amount** | **i64** | The subtransaction amount in milliunits format | 
-**memo** | **String** |  | 
-**payee_id** | **String** |  | 
-**category_id** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer, the account_id which the subtransaction transfers to | 
+**memo** | **String** |  | [optional] 
+**payee_id** | **String** |  | [optional] 
+**category_id** | **String** |  | [optional] 
+**transfer_account_id** | **String** | If a transfer, the account_id which the subtransaction transfers to | [optional] 
 **deleted** | **bool** | Whether or not the subtransaction has been deleted.  Deleted subtransactions will only be included in delta requests. | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
diff --git a/ynab-api/docs/TransactionDetail.md b/ynab-api/docs/TransactionDetail.md
index f9a1de5..ad156d7 100644
--- a/ynab-api/docs/TransactionDetail.md
+++ b/ynab-api/docs/TransactionDetail.md
@@ -7,17 +7,17 @@ Name | Type | Description | Notes
 **id** | **String** |  | 
 **date** | [***String**](string.md) | The transaction date in ISO format (e.g. 2016-12-01) | 
 **amount** | **i64** | The transaction amount in milliunits format | 
-**memo** | **String** |  | 
+**memo** | **String** |  | [optional] 
 **cleared** | **String** | The cleared status of the transaction | 
 **approved** | **bool** | Whether or not the transaction is approved | 
-**flag_color** | **String** | The transaction flag | 
+**flag_color** | **String** | The transaction flag | [optional] 
 **account_id** | **String** |  | 
-**payee_id** | **String** |  | 
-**category_id** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer transaction, the account to which it transfers | 
-**transfer_transaction_id** | **String** | If a transfer transaction, the id of transaction on the other side of the transfer | 
-**matched_transaction_id** | **String** | If transaction is matched, the id of the matched transaction | 
-**import_id** | **String** | If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'. | 
+**payee_id** | **String** |  | [optional] 
+**category_id** | **String** |  | [optional] 
+**transfer_account_id** | **String** | If a transfer transaction, the account to which it transfers | [optional] 
+**transfer_transaction_id** | **String** | If a transfer transaction, the id of transaction on the other side of the transfer | [optional] 
+**matched_transaction_id** | **String** | If transaction is matched, the id of the matched transaction | [optional] 
+**import_id** | **String** | If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'. | [optional] 
 **deleted** | **bool** | Whether or not the transaction has been deleted.  Deleted transactions will only be included in delta requests. | 
 **account_name** | **String** |  | 
 **payee_name** | **String** |  | 
diff --git a/ynab-api/docs/TransactionSummary.md b/ynab-api/docs/TransactionSummary.md
index bad149c..fd93b15 100644
--- a/ynab-api/docs/TransactionSummary.md
+++ b/ynab-api/docs/TransactionSummary.md
@@ -7,17 +7,17 @@ Name | Type | Description | Notes
 **id** | **String** |  | 
 **date** | [***String**](string.md) | The transaction date in ISO format (e.g. 2016-12-01) | 
 **amount** | **i64** | The transaction amount in milliunits format | 
-**memo** | **String** |  | 
+**memo** | **String** |  | [optional] 
 **cleared** | **String** | The cleared status of the transaction | 
 **approved** | **bool** | Whether or not the transaction is approved | 
-**flag_color** | **String** | The transaction flag | 
+**flag_color** | **String** | The transaction flag | [optional] 
 **account_id** | **String** |  | 
-**payee_id** | **String** |  | 
-**category_id** | **String** |  | 
-**transfer_account_id** | **String** | If a transfer transaction, the account to which it transfers | 
-**transfer_transaction_id** | **String** | If a transfer transaction, the id of transaction on the other side of the transfer | 
-**matched_transaction_id** | **String** | If transaction is matched, the id of the matched transaction | 
-**import_id** | **String** | If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'. | 
+**payee_id** | **String** |  | [optional] 
+**category_id** | **String** |  | [optional] 
+**transfer_account_id** | **String** | If a transfer transaction, the account to which it transfers | [optional] 
+**transfer_transaction_id** | **String** | If a transfer transaction, the id of transaction on the other side of the transfer | [optional] 
+**matched_transaction_id** | **String** | If transaction is matched, the id of the matched transaction | [optional] 
+**import_id** | **String** | If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'. | [optional] 
 **deleted** | **bool** | Whether or not the transaction has been deleted.  Deleted transactions will only be included in delta requests. | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
diff --git a/ynab-api/src/models/account.rs b/ynab-api/src/models/account.rs
index 88f0353..6ffa1d5 100644
--- a/ynab-api/src/models/account.rs
+++ b/ynab-api/src/models/account.rs
@@ -28,8 +28,8 @@ pub struct Account {
     /// Whether this account is closed or not
     #[serde(rename = "closed")]
     pub closed: bool,
-    #[serde(rename = "note")]
-    pub note: String,
+    #[serde(rename = "note", skip_serializing_if = "Option::is_none")]
+    pub note: Option<String>,
     /// The current balance of the account in milliunits format
     #[serde(rename = "balance")]
     pub balance: i64,
@@ -48,14 +48,14 @@ pub struct Account {
 }
 
 impl Account {
-    pub fn new(id: String, name: String, _type: String, on_budget: bool, closed: bool, note: String, balance: i64, cleared_balance: i64, uncleared_balance: i64, transfer_payee_id: String, deleted: bool) -> Account {
+    pub fn new(id: String, name: String, _type: String, on_budget: bool, closed: bool, balance: i64, cleared_balance: i64, uncleared_balance: i64, transfer_payee_id: String, deleted: bool) -> Account {
         Account {
             id: id,
             name: name,
             _type: _type,
             on_budget: on_budget,
             closed: closed,
-            note: note,
+            note: None,
             balance: balance,
             cleared_balance: cleared_balance,
             uncleared_balance: uncleared_balance,
diff --git a/ynab-api/src/models/budget_summary_response_data.rs b/ynab-api/src/models/budget_summary_response_data.rs
index 35f3840..f6bec05 100644
--- a/ynab-api/src/models/budget_summary_response_data.rs
+++ b/ynab-api/src/models/budget_summary_response_data.rs
@@ -17,15 +17,15 @@ use serde_json::Value;
 pub struct BudgetSummaryResponseData {
     #[serde(rename = "budgets")]
     pub budgets: Vec<::models::BudgetSummary>,
-    #[serde(rename = "default_budget")]
-    pub default_budget: ::models::BudgetSummary,
+    #[serde(rename = "default_budget", skip_serializing_if = "Option::is_none")]
+    pub default_budget: Option<::models::BudgetSummary>,
 }
 
 impl BudgetSummaryResponseData {
-    pub fn new(budgets: Vec<::models::BudgetSummary>, default_budget: ::models::BudgetSummary) -> BudgetSummaryResponseData {
+    pub fn new(budgets: Vec<::models::BudgetSummary>) -> BudgetSummaryResponseData {
         BudgetSummaryResponseData {
             budgets: budgets,
-            default_budget: default_budget,
+            default_budget: None,
         }
     }
 }
diff --git a/ynab-api/src/models/category.rs b/ynab-api/src/models/category.rs
index 1662f64..1a62c6a 100644
--- a/ynab-api/src/models/category.rs
+++ b/ynab-api/src/models/category.rs
@@ -27,8 +27,8 @@ pub struct Category {
     /// If category is hidden this is the id of the category group it originally belonged to before it was hidden.
     #[serde(rename = "original_category_group_id", skip_serializing_if = "Option::is_none")]
     pub original_category_group_id: Option<String>,
-    #[serde(rename = "note")]
-    pub note: String,
+    #[serde(rename = "note", skip_serializing_if = "Option::is_none")]
+    pub note: Option<String>,
     /// Budgeted amount in milliunits format
     #[serde(rename = "budgeted")]
     pub budgeted: i64,
@@ -39,42 +39,42 @@ pub struct Category {
     #[serde(rename = "balance")]
     pub balance: i64,
     /// The type of goal, if the cagegory has a goal (TB=Target Category Balance, TBD=Target Category Balance by Date, MF=Monthly Funding)
-    #[serde(rename = "goal_type")]
-    pub goal_type: String,
+    #[serde(rename = "goal_type", skip_serializing_if = "Option::is_none")]
+    pub goal_type: Option<String>,
     /// The month a goal was created
-    #[serde(rename = "goal_creation_month")]
-    pub goal_creation_month: String,
+    #[serde(rename = "goal_creation_month", skip_serializing_if = "Option::is_none")]
+    pub goal_creation_month: Option<String>,
     /// The goal target amount in milliunits
     #[serde(rename = "goal_target")]
     pub goal_target: i64,
     /// If the goal type is 'TBD' (Target Category Balance by Date), this is the target month for the goal to be completed
-    #[serde(rename = "goal_target_month")]
-    pub goal_target_month: String,
+    #[serde(rename = "goal_target_month", skip_serializing_if = "Option::is_none")]
+    pub goal_target_month: Option<String>,
     /// The percentage completion of the goal
-    #[serde(rename = "goal_percentage_complete")]
-    pub goal_percentage_complete: i32,
+    #[serde(rename = "goal_percentage_complete", skip_serializing_if = "Option::is_none")]
+    pub goal_percentage_complete: Option<i32>,
     /// Whether or not the category has been deleted.  Deleted categories will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
 }
 
 impl Category {
-    pub fn new(id: String, category_group_id: String, name: String, hidden: bool, note: String, budgeted: i64, activity: i64, balance: i64, goal_type: String, goal_creation_month: String, goal_target: i64, goal_target_month: String, goal_percentage_complete: i32, deleted: bool) -> Category {
+    pub fn new(id: String, category_group_id: String, name: String, hidden: bool, budgeted: i64, activity: i64, balance: i64, goal_target: i64, deleted: bool) -> Category {
         Category {
             id: id,
             category_group_id: category_group_id,
             name: name,
             hidden: hidden,
             original_category_group_id: None,
-            note: note,
+            note: None,
             budgeted: budgeted,
             activity: activity,
             balance: balance,
-            goal_type: goal_type,
-            goal_creation_month: goal_creation_month,
+            goal_type: None,
+            goal_creation_month: None,
             goal_target: goal_target,
-            goal_target_month: goal_target_month,
-            goal_percentage_complete: goal_percentage_complete,
+            goal_target_month: None,
+            goal_percentage_complete: None,
             deleted: deleted,
         }
     }
diff --git a/ynab-api/src/models/hybrid_transaction.rs b/ynab-api/src/models/hybrid_transaction.rs
index 240f49d..488872e 100644
--- a/ynab-api/src/models/hybrid_transaction.rs
+++ b/ynab-api/src/models/hybrid_transaction.rs
@@ -23,8 +23,8 @@ pub struct HybridTransaction {
     /// The transaction amount in milliunits format
     #[serde(rename = "amount")]
     pub amount: i64,
-    #[serde(rename = "memo")]
-    pub memo: String,
+    #[serde(rename = "memo", skip_serializing_if = "Option::is_none")]
+    pub memo: Option<String>,
     /// The cleared status of the transaction
     #[serde(rename = "cleared")]
     pub cleared: String,
@@ -32,26 +32,26 @@ pub struct HybridTransaction {
     #[serde(rename = "approved")]
     pub approved: bool,
     /// The transaction flag
-    #[serde(rename = "flag_color")]
-    pub flag_color: String,
+    #[serde(rename = "flag_color", skip_serializing_if = "Option::is_none")]
+    pub flag_color: Option<String>,
     #[serde(rename = "account_id")]
     pub account_id: String,
-    #[serde(rename = "payee_id")]
-    pub payee_id: String,
-    #[serde(rename = "category_id")]
-    pub category_id: String,
+    #[serde(rename = "payee_id", skip_serializing_if = "Option::is_none")]
+    pub payee_id: Option<String>,
+    #[serde(rename = "category_id", skip_serializing_if = "Option::is_none")]
+    pub category_id: Option<String>,
     /// If a transfer transaction, the account to which it transfers
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// If a transfer transaction, the id of transaction on the other side of the transfer
-    #[serde(rename = "transfer_transaction_id")]
-    pub transfer_transaction_id: String,
+    #[serde(rename = "transfer_transaction_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_transaction_id: Option<String>,
     /// If transaction is matched, the id of the matched transaction
-    #[serde(rename = "matched_transaction_id")]
-    pub matched_transaction_id: String,
+    #[serde(rename = "matched_transaction_id", skip_serializing_if = "Option::is_none")]
+    pub matched_transaction_id: Option<String>,
     /// If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'.
-    #[serde(rename = "import_id")]
-    pub import_id: String,
+    #[serde(rename = "import_id", skip_serializing_if = "Option::is_none")]
+    pub import_id: Option<String>,
     /// Whether or not the transaction has been deleted.  Deleted transactions will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
@@ -70,22 +70,22 @@ pub struct HybridTransaction {
 }
 
 impl HybridTransaction {
-    pub fn new(id: String, date: String, amount: i64, memo: String, cleared: String, approved: bool, flag_color: String, account_id: String, payee_id: String, category_id: String, transfer_account_id: String, transfer_transaction_id: String, matched_transaction_id: String, import_id: String, deleted: bool, _type: String, parent_transaction_id: String, account_name: String, payee_name: String, category_name: String) -> HybridTransaction {
+    pub fn new(id: String, date: String, amount: i64, cleared: String, approved: bool, account_id: String, deleted: bool, _type: String, parent_transaction_id: String, account_name: String, payee_name: String, category_name: String) -> HybridTransaction {
         HybridTransaction {
             id: id,
             date: date,
             amount: amount,
-            memo: memo,
+            memo: None,
             cleared: cleared,
             approved: approved,
-            flag_color: flag_color,
+            flag_color: None,
             account_id: account_id,
-            payee_id: payee_id,
-            category_id: category_id,
-            transfer_account_id: transfer_account_id,
-            transfer_transaction_id: transfer_transaction_id,
-            matched_transaction_id: matched_transaction_id,
-            import_id: import_id,
+            payee_id: None,
+            category_id: None,
+            transfer_account_id: None,
+            transfer_transaction_id: None,
+            matched_transaction_id: None,
+            import_id: None,
             deleted: deleted,
             _type: _type,
             parent_transaction_id: parent_transaction_id,
diff --git a/ynab-api/src/models/month_detail.rs b/ynab-api/src/models/month_detail.rs
index 9a2b1c2..a6f55d4 100644
--- a/ynab-api/src/models/month_detail.rs
+++ b/ynab-api/src/models/month_detail.rs
@@ -17,8 +17,8 @@ use serde_json::Value;
 pub struct MonthDetail {
     #[serde(rename = "month")]
     pub month: String,
-    #[serde(rename = "note")]
-    pub note: String,
+    #[serde(rename = "note", skip_serializing_if = "Option::is_none")]
+    pub note: Option<String>,
     /// The total amount in transactions categorized to 'Inflow: To be Budgeted' in the month
     #[serde(rename = "income")]
     pub income: i64,
@@ -32,8 +32,8 @@ pub struct MonthDetail {
     #[serde(rename = "to_be_budgeted")]
     pub to_be_budgeted: i64,
     /// The Age of Money as of the month
-    #[serde(rename = "age_of_money")]
-    pub age_of_money: i32,
+    #[serde(rename = "age_of_money", skip_serializing_if = "Option::is_none")]
+    pub age_of_money: Option<i32>,
     /// Whether or not the month has been deleted.  Deleted months will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
@@ -43,15 +43,15 @@ pub struct MonthDetail {
 }
 
 impl MonthDetail {
-    pub fn new(month: String, note: String, income: i64, budgeted: i64, activity: i64, to_be_budgeted: i64, age_of_money: i32, deleted: bool, categories: Vec<::models::Category>) -> MonthDetail {
+    pub fn new(month: String, income: i64, budgeted: i64, activity: i64, to_be_budgeted: i64, deleted: bool, categories: Vec<::models::Category>) -> MonthDetail {
         MonthDetail {
             month: month,
-            note: note,
+            note: None,
             income: income,
             budgeted: budgeted,
             activity: activity,
             to_be_budgeted: to_be_budgeted,
-            age_of_money: age_of_money,
+            age_of_money: None,
             deleted: deleted,
             categories: categories,
         }
diff --git a/ynab-api/src/models/month_summary.rs b/ynab-api/src/models/month_summary.rs
index c7e980a..3c705d3 100644
--- a/ynab-api/src/models/month_summary.rs
+++ b/ynab-api/src/models/month_summary.rs
@@ -17,8 +17,8 @@ use serde_json::Value;
 pub struct MonthSummary {
     #[serde(rename = "month")]
     pub month: String,
-    #[serde(rename = "note")]
-    pub note: String,
+    #[serde(rename = "note", skip_serializing_if = "Option::is_none")]
+    pub note: Option<String>,
     /// The total amount in transactions categorized to 'Inflow: To be Budgeted' in the month
     #[serde(rename = "income")]
     pub income: i64,
@@ -32,23 +32,23 @@ pub struct MonthSummary {
     #[serde(rename = "to_be_budgeted")]
     pub to_be_budgeted: i64,
     /// The Age of Money as of the month
-    #[serde(rename = "age_of_money")]
-    pub age_of_money: i32,
+    #[serde(rename = "age_of_money", skip_serializing_if = "Option::is_none")]
+    pub age_of_money: Option<i32>,
     /// Whether or not the month has been deleted.  Deleted months will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
 }
 
 impl MonthSummary {
-    pub fn new(month: String, note: String, income: i64, budgeted: i64, activity: i64, to_be_budgeted: i64, age_of_money: i32, deleted: bool) -> MonthSummary {
+    pub fn new(month: String, income: i64, budgeted: i64, activity: i64, to_be_budgeted: i64, deleted: bool) -> MonthSummary {
         MonthSummary {
             month: month,
-            note: note,
+            note: None,
             income: income,
             budgeted: budgeted,
             activity: activity,
             to_be_budgeted: to_be_budgeted,
-            age_of_money: age_of_money,
+            age_of_money: None,
             deleted: deleted,
         }
     }
diff --git a/ynab-api/src/models/payee.rs b/ynab-api/src/models/payee.rs
index 2508b31..13ad103 100644
--- a/ynab-api/src/models/payee.rs
+++ b/ynab-api/src/models/payee.rs
@@ -20,19 +20,19 @@ pub struct Payee {
     #[serde(rename = "name")]
     pub name: String,
     /// If a transfer payee, the account_id to which this payee transfers to
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// Whether or not the payee has been deleted.  Deleted payees will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
 }
 
 impl Payee {
-    pub fn new(id: String, name: String, transfer_account_id: String, deleted: bool) -> Payee {
+    pub fn new(id: String, name: String, deleted: bool) -> Payee {
         Payee {
             id: id,
             name: name,
-            transfer_account_id: transfer_account_id,
+            transfer_account_id: None,
             deleted: deleted,
         }
     }
diff --git a/ynab-api/src/models/scheduled_sub_transaction.rs b/ynab-api/src/models/scheduled_sub_transaction.rs
index 760fa78..dfc0aca 100644
--- a/ynab-api/src/models/scheduled_sub_transaction.rs
+++ b/ynab-api/src/models/scheduled_sub_transaction.rs
@@ -22,30 +22,30 @@ pub struct ScheduledSubTransaction {
     /// The scheduled subtransaction amount in milliunits format
     #[serde(rename = "amount")]
     pub amount: i64,
-    #[serde(rename = "memo")]
-    pub memo: String,
-    #[serde(rename = "payee_id")]
-    pub payee_id: String,
+    #[serde(rename = "memo", skip_serializing_if = "Option::is_none")]
+    pub memo: Option<String>,
+    #[serde(rename = "payee_id", skip_serializing_if = "Option::is_none")]
+    pub payee_id: Option<String>,
     #[serde(rename = "category_id")]
     pub category_id: String,
     /// If a transfer, the account_id which the scheduled subtransaction transfers to
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// Whether or not the scheduled subtransaction has been deleted.  Deleted scheduled subtransactions will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
 }
 
 impl ScheduledSubTransaction {
-    pub fn new(id: String, scheduled_transaction_id: String, amount: i64, memo: String, payee_id: String, category_id: String, transfer_account_id: String, deleted: bool) -> ScheduledSubTransaction {
+    pub fn new(id: String, scheduled_transaction_id: String, amount: i64, category_id: String, deleted: bool) -> ScheduledSubTransaction {
         ScheduledSubTransaction {
             id: id,
             scheduled_transaction_id: scheduled_transaction_id,
             amount: amount,
-            memo: memo,
-            payee_id: payee_id,
+            memo: None,
+            payee_id: None,
             category_id: category_id,
-            transfer_account_id: transfer_account_id,
+            transfer_account_id: None,
             deleted: deleted,
         }
     }
diff --git a/ynab-api/src/models/scheduled_transaction_detail.rs b/ynab-api/src/models/scheduled_transaction_detail.rs
index 65c2473..d86ef25 100644
--- a/ynab-api/src/models/scheduled_transaction_detail.rs
+++ b/ynab-api/src/models/scheduled_transaction_detail.rs
@@ -28,20 +28,20 @@ pub struct ScheduledTransactionDetail {
     /// The scheduled transaction amount in milliunits format
     #[serde(rename = "amount")]
     pub amount: i64,
-    #[serde(rename = "memo")]
-    pub memo: String,
+    #[serde(rename = "memo", skip_serializing_if = "Option::is_none")]
+    pub memo: Option<String>,
     /// The scheduled transaction flag
     #[serde(rename = "flag_color")]
     pub flag_color: String,
     #[serde(rename = "account_id")]
     pub account_id: String,
-    #[serde(rename = "payee_id")]
-    pub payee_id: String,
+    #[serde(rename = "payee_id", skip_serializing_if = "Option::is_none")]
+    pub payee_id: Option<String>,
     #[serde(rename = "category_id")]
     pub category_id: String,
     /// If a transfer, the account_id which the scheduled transaction transfers to
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// Whether or not the scheduled transaction has been deleted.  Deleted scheduled transactions will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
@@ -57,19 +57,19 @@ pub struct ScheduledTransactionDetail {
 }
 
 impl ScheduledTransactionDetail {
-    pub fn new(id: String, date_first: String, date_next: String, frequency: String, amount: i64, memo: String, flag_color: String, account_id: String, payee_id: String, category_id: String, transfer_account_id: String, deleted: bool, account_name: String, payee_name: String, category_name: String, subtransactions: Vec<::models::ScheduledSubTransaction>) -> ScheduledTransactionDetail {
+    pub fn new(id: String, date_first: String, date_next: String, frequency: String, amount: i64, flag_color: String, account_id: String, category_id: String, deleted: bool, account_name: String, payee_name: String, category_name: String, subtransactions: Vec<::models::ScheduledSubTransaction>) -> ScheduledTransactionDetail {
         ScheduledTransactionDetail {
             id: id,
             date_first: date_first,
             date_next: date_next,
             frequency: frequency,
             amount: amount,
-            memo: memo,
+            memo: None,
             flag_color: flag_color,
             account_id: account_id,
-            payee_id: payee_id,
+            payee_id: None,
             category_id: category_id,
-            transfer_account_id: transfer_account_id,
+            transfer_account_id: None,
             deleted: deleted,
             account_name: account_name,
             payee_name: payee_name,
diff --git a/ynab-api/src/models/scheduled_transaction_summary.rs b/ynab-api/src/models/scheduled_transaction_summary.rs
index dfd6f1f..7966d2c 100644
--- a/ynab-api/src/models/scheduled_transaction_summary.rs
+++ b/ynab-api/src/models/scheduled_transaction_summary.rs
@@ -28,39 +28,39 @@ pub struct ScheduledTransactionSummary {
     /// The scheduled transaction amount in milliunits format
     #[serde(rename = "amount")]
     pub amount: i64,
-    #[serde(rename = "memo")]
-    pub memo: String,
+    #[serde(rename = "memo", skip_serializing_if = "Option::is_none")]
+    pub memo: Option<String>,
     /// The scheduled transaction flag
     #[serde(rename = "flag_color")]
     pub flag_color: String,
     #[serde(rename = "account_id")]
     pub account_id: String,
-    #[serde(rename = "payee_id")]
-    pub payee_id: String,
+    #[serde(rename = "payee_id", skip_serializing_if = "Option::is_none")]
+    pub payee_id: Option<String>,
     #[serde(rename = "category_id")]
     pub category_id: String,
     /// If a transfer, the account_id which the scheduled transaction transfers to
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// Whether or not the scheduled transaction has been deleted.  Deleted scheduled transactions will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
 }
 
 impl ScheduledTransactionSummary {
-    pub fn new(id: String, date_first: String, date_next: String, frequency: String, amount: i64, memo: String, flag_color: String, account_id: String, payee_id: String, category_id: String, transfer_account_id: String, deleted: bool) -> ScheduledTransactionSummary {
+    pub fn new(id: String, date_first: String, date_next: String, frequency: String, amount: i64, flag_color: String, account_id: String, category_id: String, deleted: bool) -> ScheduledTransactionSummary {
         ScheduledTransactionSummary {
             id: id,
             date_first: date_first,
             date_next: date_next,
             frequency: frequency,
             amount: amount,
-            memo: memo,
+            memo: None,
             flag_color: flag_color,
             account_id: account_id,
-            payee_id: payee_id,
+            payee_id: None,
             category_id: category_id,
-            transfer_account_id: transfer_account_id,
+            transfer_account_id: None,
             deleted: deleted,
         }
     }
diff --git a/ynab-api/src/models/sub_transaction.rs b/ynab-api/src/models/sub_transaction.rs
index aa7ed37..633ae38 100644
--- a/ynab-api/src/models/sub_transaction.rs
+++ b/ynab-api/src/models/sub_transaction.rs
@@ -22,30 +22,30 @@ pub struct SubTransaction {
     /// The subtransaction amount in milliunits format
     #[serde(rename = "amount")]
     pub amount: i64,
-    #[serde(rename = "memo")]
-    pub memo: String,
-    #[serde(rename = "payee_id")]
-    pub payee_id: String,
-    #[serde(rename = "category_id")]
-    pub category_id: String,
+    #[serde(rename = "memo", skip_serializing_if = "Option::is_none")]
+    pub memo: Option<String>,
+    #[serde(rename = "payee_id", skip_serializing_if = "Option::is_none")]
+    pub payee_id: Option<String>,
+    #[serde(rename = "category_id", skip_serializing_if = "Option::is_none")]
+    pub category_id: Option<String>,
     /// If a transfer, the account_id which the subtransaction transfers to
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// Whether or not the subtransaction has been deleted.  Deleted subtransactions will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
 }
 
 impl SubTransaction {
-    pub fn new(id: String, transaction_id: String, amount: i64, memo: String, payee_id: String, category_id: String, transfer_account_id: String, deleted: bool) -> SubTransaction {
+    pub fn new(id: String, transaction_id: String, amount: i64, deleted: bool) -> SubTransaction {
         SubTransaction {
             id: id,
             transaction_id: transaction_id,
             amount: amount,
-            memo: memo,
-            payee_id: payee_id,
-            category_id: category_id,
-            transfer_account_id: transfer_account_id,
+            memo: None,
+            payee_id: None,
+            category_id: None,
+            transfer_account_id: None,
             deleted: deleted,
         }
     }
diff --git a/ynab-api/src/models/transaction_detail.rs b/ynab-api/src/models/transaction_detail.rs
index 1558c7c..361813b 100644
--- a/ynab-api/src/models/transaction_detail.rs
+++ b/ynab-api/src/models/transaction_detail.rs
@@ -23,8 +23,8 @@ pub struct TransactionDetail {
     /// The transaction amount in milliunits format
     #[serde(rename = "amount")]
     pub amount: i64,
-    #[serde(rename = "memo")]
-    pub memo: String,
+    #[serde(rename = "memo", skip_serializing_if = "Option::is_none")]
+    pub memo: Option<String>,
     /// The cleared status of the transaction
     #[serde(rename = "cleared")]
     pub cleared: String,
@@ -32,26 +32,26 @@ pub struct TransactionDetail {
     #[serde(rename = "approved")]
     pub approved: bool,
     /// The transaction flag
-    #[serde(rename = "flag_color")]
-    pub flag_color: String,
+    #[serde(rename = "flag_color", skip_serializing_if = "Option::is_none")]
+    pub flag_color: Option<String>,
     #[serde(rename = "account_id")]
     pub account_id: String,
-    #[serde(rename = "payee_id")]
-    pub payee_id: String,
-    #[serde(rename = "category_id")]
-    pub category_id: String,
+    #[serde(rename = "payee_id", skip_serializing_if = "Option::is_none")]
+    pub payee_id: Option<String>,
+    #[serde(rename = "category_id", skip_serializing_if = "Option::is_none")]
+    pub category_id: Option<String>,
     /// If a transfer transaction, the account to which it transfers
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// If a transfer transaction, the id of transaction on the other side of the transfer
-    #[serde(rename = "transfer_transaction_id")]
-    pub transfer_transaction_id: String,
+    #[serde(rename = "transfer_transaction_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_transaction_id: Option<String>,
     /// If transaction is matched, the id of the matched transaction
-    #[serde(rename = "matched_transaction_id")]
-    pub matched_transaction_id: String,
+    #[serde(rename = "matched_transaction_id", skip_serializing_if = "Option::is_none")]
+    pub matched_transaction_id: Option<String>,
     /// If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'.
-    #[serde(rename = "import_id")]
-    pub import_id: String,
+    #[serde(rename = "import_id", skip_serializing_if = "Option::is_none")]
+    pub import_id: Option<String>,
     /// Whether or not the transaction has been deleted.  Deleted transactions will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
@@ -67,22 +67,22 @@ pub struct TransactionDetail {
 }
 
 impl TransactionDetail {
-    pub fn new(id: String, date: String, amount: i64, memo: String, cleared: String, approved: bool, flag_color: String, account_id: String, payee_id: String, category_id: String, transfer_account_id: String, transfer_transaction_id: String, matched_transaction_id: String, import_id: String, deleted: bool, account_name: String, payee_name: String, category_name: String, subtransactions: Vec<::models::SubTransaction>) -> TransactionDetail {
+    pub fn new(id: String, date: String, amount: i64, cleared: String, approved: bool, account_id: String, deleted: bool, account_name: String, payee_name: String, category_name: String, subtransactions: Vec<::models::SubTransaction>) -> TransactionDetail {
         TransactionDetail {
             id: id,
             date: date,
             amount: amount,
-            memo: memo,
+            memo: None,
             cleared: cleared,
             approved: approved,
-            flag_color: flag_color,
+            flag_color: None,
             account_id: account_id,
-            payee_id: payee_id,
-            category_id: category_id,
-            transfer_account_id: transfer_account_id,
-            transfer_transaction_id: transfer_transaction_id,
-            matched_transaction_id: matched_transaction_id,
-            import_id: import_id,
+            payee_id: None,
+            category_id: None,
+            transfer_account_id: None,
+            transfer_transaction_id: None,
+            matched_transaction_id: None,
+            import_id: None,
             deleted: deleted,
             account_name: account_name,
             payee_name: payee_name,
diff --git a/ynab-api/src/models/transaction_summary.rs b/ynab-api/src/models/transaction_summary.rs
index 31ef1c5..94ce164 100644
--- a/ynab-api/src/models/transaction_summary.rs
+++ b/ynab-api/src/models/transaction_summary.rs
@@ -23,8 +23,8 @@ pub struct TransactionSummary {
     /// The transaction amount in milliunits format
     #[serde(rename = "amount")]
     pub amount: i64,
-    #[serde(rename = "memo")]
-    pub memo: String,
+    #[serde(rename = "memo", skip_serializing_if = "Option::is_none")]
+    pub memo: Option<String>,
     /// The cleared status of the transaction
     #[serde(rename = "cleared")]
     pub cleared: String,
@@ -32,48 +32,48 @@ pub struct TransactionSummary {
     #[serde(rename = "approved")]
     pub approved: bool,
     /// The transaction flag
-    #[serde(rename = "flag_color")]
-    pub flag_color: String,
+    #[serde(rename = "flag_color", skip_serializing_if = "Option::is_none")]
+    pub flag_color: Option<String>,
     #[serde(rename = "account_id")]
     pub account_id: String,
-    #[serde(rename = "payee_id")]
-    pub payee_id: String,
-    #[serde(rename = "category_id")]
-    pub category_id: String,
+    #[serde(rename = "payee_id", skip_serializing_if = "Option::is_none")]
+    pub payee_id: Option<String>,
+    #[serde(rename = "category_id", skip_serializing_if = "Option::is_none")]
+    pub category_id: Option<String>,
     /// If a transfer transaction, the account to which it transfers
-    #[serde(rename = "transfer_account_id")]
-    pub transfer_account_id: String,
+    #[serde(rename = "transfer_account_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_account_id: Option<String>,
     /// If a transfer transaction, the id of transaction on the other side of the transfer
-    #[serde(rename = "transfer_transaction_id")]
-    pub transfer_transaction_id: String,
+    #[serde(rename = "transfer_transaction_id", skip_serializing_if = "Option::is_none")]
+    pub transfer_transaction_id: Option<String>,
     /// If transaction is matched, the id of the matched transaction
-    #[serde(rename = "matched_transaction_id")]
-    pub matched_transaction_id: String,
+    #[serde(rename = "matched_transaction_id", skip_serializing_if = "Option::is_none")]
+    pub matched_transaction_id: Option<String>,
     /// If the Transaction was imported, this field is a unique (by account) import identifier.  If this transaction was imported through File Based Import or Direct Import and not through the API, the import_id will have the format: 'YNAB:[milliunit_amount]:[iso_date]:[occurrence]'.  For example, a transaction dated 2015-12-30 in the amount of -$294.23 USD would have an import_id of 'YNAB:-294230:2015-12-30:1'.  If a second transaction on the same account was imported and had the same date and same amount, its import_id would be 'YNAB:-294230:2015-12-30:2'.
-    #[serde(rename = "import_id")]
-    pub import_id: String,
+    #[serde(rename = "import_id", skip_serializing_if = "Option::is_none")]
+    pub import_id: Option<String>,
     /// Whether or not the transaction has been deleted.  Deleted transactions will only be included in delta requests.
     #[serde(rename = "deleted")]
     pub deleted: bool,
 }
 
 impl TransactionSummary {
-    pub fn new(id: String, date: String, amount: i64, memo: String, cleared: String, approved: bool, flag_color: String, account_id: String, payee_id: String, category_id: String, transfer_account_id: String, transfer_transaction_id: String, matched_transaction_id: String, import_id: String, deleted: bool) -> TransactionSummary {
+    pub fn new(id: String, date: String, amount: i64, cleared: String, approved: bool, account_id: String, deleted: bool) -> TransactionSummary {
         TransactionSummary {
             id: id,
             date: date,
             amount: amount,
-            memo: memo,
+            memo: None,
             cleared: cleared,
             approved: approved,
-            flag_color: flag_color,
+            flag_color: None,
             account_id: account_id,
-            payee_id: payee_id,
-            category_id: category_id,
-            transfer_account_id: transfer_account_id,
-            transfer_transaction_id: transfer_transaction_id,
-            matched_transaction_id: matched_transaction_id,
-            import_id: import_id,
+            payee_id: None,
+            category_id: None,
+            transfer_account_id: None,
+            transfer_transaction_id: None,
+            matched_transaction_id: None,
+            import_id: None,
             deleted: deleted,
         }
     }