> ## Documentation Index
> Fetch the complete documentation index at: https://docs.loyalty.dog/llms.txt
> Use this file to discover all available pages before exploring further.

# Update merchant default language

> Updates the default language for a merchant (program).



## OpenAPI

````yaml https://api.loyalty.dog/openapi.json patch /v2/localization/merchants/{merchant_id}/language
openapi: 3.1.0
info:
  title: LoyaltyDog
  description: >-

    Welcome to the LoyaltyDog API! This API provides access to our loyalty
    program features, allowing you to integrate with various platforms and
    manage your loyalty data.


    Want to query LoyaltyDog via an AI assistant (Claude, Cursor, Windsurf)? See
    the [MCP Integration guide](https://loyaltydog.ai/playground#mcp).
        
  termsOfService: https://loyalty.dog/loyalty-program-terms-service
  contact:
    name: LoyaltyDog Support
    url: https://loyalty.dog/contact-us
    email: support@loyalty.dog
  version: 1.0.1
servers:
  - url: https://api.loyalty.dog
    description: Production
security:
  - bearerAuth: []
paths:
  /v2/localization/merchants/{merchant_id}/language:
    patch:
      tags:
        - Localization
      summary: Update merchant default language
      description: Updates the default language for a merchant (program).
      operationId: >-
        update_merchant_language_v2_localization_merchants__merchant_id__language_patch
      parameters:
        - name: merchant_id
          in: path
          required: true
          schema:
            $ref: '#/components/schemas/PydanticObjectId'
        - name: authorization
          in: header
          required: false
          schema:
            anyOf:
              - type: string
              - type: 'null'
            title: Authorization
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/LanguagePreferenceUpdate'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MerchantLanguageUpdateResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
components:
  schemas:
    PydanticObjectId:
      type: string
      maxLength: 24
      minLength: 24
      pattern: ^[0-9a-f]{24}$
      example: 5eb7cf5a86d9755df3a6c593
    LanguagePreferenceUpdate:
      properties:
        languageCode:
          type: string
          maxLength: 10
          minLength: 2
          title: Languagecode
          description: Language code (e.g., 'en-US', 'es-ES')
      type: object
      required:
        - languageCode
      title: LanguagePreferenceUpdate
      description: Request model for updating language preference.
    MerchantLanguageUpdateResponse:
      properties:
        id:
          $ref: '#/components/schemas/PydanticObjectId'
        sid:
          type: string
          title: Sid
        defaultLanguage:
          anyOf:
            - type: string
            - type: 'null'
          title: Defaultlanguage
        languagePreference:
          anyOf:
            - additionalProperties: true
              type: object
            - type: 'null'
          title: Languagepreference
          description: Language preference info
      type: object
      required:
        - id
        - sid
        - defaultLanguage
      title: MerchantLanguageUpdateResponse
      description: Response model for merchant language update.
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
        - loc
        - msg
        - type
      title: ValidationError
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: JWT access token obtained from POST /v2/token.

````