> For the complete documentation index, see [llms.txt](https://apidocs.akinon.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://apidocs.akinon.com/commerce-openapis/checkout/alternative-payment-methods/submit-cash-register-installment-selection.md).

# Submit Cash Register Installment Selection

Submits the installment selection for the cash register payment. Exactly one of `installment` or `no_installment` must be provided.

**Required Fields** (mutually exclusive — exactly one must be submitted):

* `installment`: Primary key of the selected installment option
* `no_installment`: Explicit confirmation to proceed without installment (`true`)

**Validation Rules**:

* Providing both `installment` and `no_installment` is invalid
* Providing neither `installment` nor `no_installment` is invalid
* The `installment` pk must reference an active installment record

**Navigation After Success**:

* Routes to `CashRegisterCompletePage`

```json
{"openapi":"3.1.0","info":{"title":"Overview","version":"1.0.0"},"tags":[{"name":"Alternative Payment Methods","description":"# Checkout Alternative Payment Methods\n\nIntegrate Bex (BKM Express), Garanti Pay (GPay), Cash Register, and Confirmation Payment into your checkout. Each method follows a distinct step sequence—use the one that matches your storefront configuration.\n\n**Bex** is a bank consortium payment method. The flow covers BIN lookup, nonce generation, installment selection, and payment completion.\n\n**Garanti Pay (GPay)** redirects customers to an external page for QR-code or link-based payment and returns them upon completion.\n\n**Cash Register** is a point-of-sale method for store staff. It supports installment selection and in-store payment completion.\n\n**Confirmation Payment** lets the customer place an order first and confirm payment later through a separate channel. The flow includes agreement review and a confirmation step.\n\n## Authentication\n\nThese endpoints support both authenticated and anonymous sessions.\n\n- **Authenticated users**: Session cookie (`sessionid`) tracks checkout progress.\n- **Anonymous users**: Guest checkout is available when the `CAN_GUEST_PURCHASE` setting is enabled.\n## Request Format\n\nInclude the following header in all checkout requests:\n\n- **x-requested-with**: `XMLHttpRequest`\n\n## Dynamic Settings\n\nThe following settings are managed at runtime through the admin interface and do not require a server restart.\n\n### CASH_REGISTER_AUTH_CONF\nAuthentication credentials for the cash register payment service. Includes the service username and password.\n\n### INSTALLMENT_FILTERS\nFilters applied during Bex and Cash Register installment selection to restrict the available options.\n\n## Static Settings\n\nThe following settings are configured in the server environment and require a restart to take effect.\n\n### DEFAULT_CARD_SLUG\nFallback card identifier used when a Bex BIN number lookup returns no match. Defaults to `other`.\n\n### GPAY_BIN_NUMBER\nThe identifier used to look up the virtual card for Garanti Pay transactions. Must match a record in the database. Defaults to `GPAY00`.\n\n### CASH_REGISTER_DEFAULTS\nFallback store staff information (staff ID, email address, and store ID) used when the corresponding request headers are absent."}],"servers":[{"description":"Akinon Checkout API","url":"https://{commerce_url}","variables":{"commerce_url":{"default":"sandbox.akinon.com"}}}],"paths":{"/orders/checkout/?page=CashRegisterInstallmentSelectionPage":{"post":{"tags":["Alternative Payment Methods"],"operationId":"submitCashRegisterInstallmentSelection","summary":"Submit Cash Register Installment Selection","description":"Submits the installment selection for the cash register payment.\nExactly one of `installment` or `no_installment` must be provided.\n\n**Required Fields** (mutually exclusive — exactly one must be submitted):\n- `installment`: Primary key of the selected installment option\n- `no_installment`: Explicit confirmation to proceed without installment (`true`)\n\n**Validation Rules**:\n- Providing both `installment` and `no_installment` is invalid\n- Providing neither `installment` nor `no_installment` is invalid\n- The `installment` pk must reference an active installment record\n\n**Navigation After Success**:\n- Routes to `CashRegisterCompletePage`","parameters":[{"$ref":"#/components/parameters/AjaxRequestHeader"},{"$ref":"#/components/parameters/SessionCookieHeader"}],"requestBody":{"required":true,"content":{"application/x-www-form-urlencoded":{"schema":{"$ref":"#/components/schemas/CashRegisterInstallmentSelectionInput"}}}},"responses":{"200":{"description":"Installment selection submitted successfully","content":{"application/json":{"schema":{"$ref":"#/components/schemas/CheckoutResponse"}}}},"302":{"description":"Redirect to basket (empty basket)"}}}}},"components":{"parameters":{"AjaxRequestHeader":{"name":"x-requested-with","in":"header","required":true,"description":"Required header for AJAX requests. 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shipping option with calculated amount","properties":{"pk":{"type":"integer"},"name":{"type":"string"},"slug":{"type":"string"},"logo":{"oneOf":[{"type":"string","format":"uri"},{"type":"null"}]},"shipping_amount":{"type":"string","pattern":"^\\d+\\.\\d{2}$"},"description":{"oneOf":[{"type":"string"},{"type":"null"}]},"kwargs":{"type":"object","additionalProperties":true}}},"PaymentOptionDetail":{"type":"object","description":"Detailed payment option with type information","properties":{"pk":{"type":"integer"},"name":{"type":"string"},"slug":{"type":"string"},"payment_type":{"type":"string","enum":["credit_card","funds_transfer","bkm_express","loyalty_money","cash_register","gpay","redirection","stored_card","masterpass","masterpass_rest","credit_payment","pay_later","saved_card","confirmation","b2b","wallet","pay_on_delivery"]},"payment_type_label":{"type":"string"}}},"Installment":{"type":"object","properties":{"pk":{"type":"integer"},"installment_count":{"type":"integer"},"label":{"type":"string"},"price_with_accrued_interest":{"type":"string","pattern":"^\\d+\\.\\d{2}$"},"monthly_price_with_accrued_interest":{"type":"string","pattern":"^\\d+\\.\\d{2}$"}}},"DeliveryOption":{"type":"object","properties":{"pk":{"type":"integer"},"name":{"type":"string"},"delivery_option_type":{"type":"string","enum":["customer","retail_store","pickup_location"]},"is_active":{"type":"boolean"}}},"RetailStore":{"type":"object","properties":{"pk":{"type":"integer"},"name":{"type":"string"},"erp_code":{"type":"string"},"township":{"$ref":"#/components/schemas/Township"},"click_and_collect":{"type":"boolean"},"is_active":{"type":"boolean"}}},"BankAccount":{"type":"object","description":"Bank 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```


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