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

# Create a custom field definition

> **Required scope:** `write_custom_field_definitions` (for API-key authentication).



## OpenAPI

````yaml /api-reference/admin.yaml post /api/v3/admin/custom_field_definitions
openapi: 3.0.3
info:
  title: Admin API
  contact:
    name: Spree Commerce
    url: https://spreecommerce.org
    email: hello@spreecommerce.org
  description: >
    Spree Admin API v3 - Administrative API for managing products, orders, and
    store settings.


    ## Authentication


    The Admin API requires a secret API key passed in the `x-spree-api-key`
    header.

    Secret API keys can be generated in the Spree admin dashboard.


    ## Response Format


    All responses are JSON. List endpoints return paginated responses with
    `data` and `meta` keys.

    Single resource endpoints return a flat JSON object.


    ## Resource IDs


    Every resource is identified by an opaque string ID (e.g. `prod_86Rf07xd4z`,

    `variant_k5nR8xLq`, `or_UkLWZg9DAJ`). Use these IDs everywhere — URL paths,

    request bodies, and Ransack filters all accept them directly.


    ## Error Handling


    Errors return a consistent format:

    ```json

    {
      "error": {
        "code": "validation_error",
        "message": "Validation failed",
        "details": { "name": ["can't be blank"] }
      }
    }

    ```
  version: v3
servers:
  - url: http://{defaultHost}
    variables:
      defaultHost:
        default: localhost:3000
security: []
tags:
  - name: Authentication
    description: Admin user authentication
  - name: Product Catalog
    description: Products, variants, and option types
  - name: Orders
    description: >-
      Order management — orders, items, payments, fulfillments, refunds, gift
      cards, store credits
  - name: Customers
    description: Customer management — profiles, addresses, store credits, credit cards
  - name: Configuration
    description: Store configuration — payment methods, tag autocomplete
paths:
  /api/v3/admin/custom_field_definitions:
    post:
      tags:
        - Custom Fields
      summary: Create a custom field definition
      description: >-
        **Required scope:** `write_custom_field_definitions` (for API-key
        authentication).
      parameters:
        - name: x-spree-api-key
          in: header
          required: true
          schema:
            type: string
        - name: Authorization
          in: header
          required: true
          schema:
            type: string
      requestBody:
        content:
          application/json:
            schema:
              type: object
              required:
                - key
                - field_type
                - resource_type
              properties:
                namespace:
                  type: string
                  description: Defaults to `custom`
                key:
                  type: string
                label:
                  type: string
                  description: Human-readable name; defaults to titleized `key`
                field_type:
                  type: string
                  description: >-
                    Custom field type identifier (one of the registered
                    field-type class names).
                resource_type:
                  type: string
                  description: Owner class, e.g. `Spree::Product`
                storefront_visible:
                  type: boolean
                  description: >-
                    When false, definition is admin-only (was `display_on:
                    back_end`)
      responses:
        '201':
          description: definition created
          content:
            application/json:
              example:
                id: cfdef_EfhxLZ9ck8
                namespace: specs
                key: origin
                label: Country of Origin
                field_type: short_text
                resource_type: Spree::Product
                storefront_visible: true
                created_at: '2026-05-17T22:57:24.816Z'
                updated_at: '2026-05-17T22:57:24.816Z'
      security:
        - api_key: []
          bearer_auth: []
      x-codeSamples:
        - lang: javascript
          label: Spree Admin SDK
          source: |-
            import { createAdminClient } from '@spree/admin-sdk'

            const client = createAdminClient({
              baseUrl: 'https://your-store.com',
              secretKey: 'sk_xxx',
            })

            const definition = await client.customFieldDefinitions.create({
              namespace: 'specs',
              key: 'origin',
              label: 'Country of Origin',
              field_type: 'short_text',
              resource_type: 'Spree::Product',
              storefront_visible: true,
            })
components:
  securitySchemes:
    api_key:
      type: apiKey
      name: x-spree-api-key
      in: header
      description: Secret API key for admin access
    bearer_auth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: JWT token for admin user authentication

````