openapi: 3.1.0
info:
  title: WeChat Mini Program Server API (subset) Access Token User Information API
  description: 'Subset OpenAPI description for the WeChat (Weixin) Mini Programs server-side

    API hosted at `api.weixin.qq.com`. Covers the foundational endpoints needed

    to bootstrap a Mini Program backend: exchanging a temporary login code for

    a session via `auth.code2Session`, minting an application access token via

    `auth.getAccessToken`, and retrieving a paid-only UnionID via

    `auth.getPaidUnionId`.


    Authentication for these foundational endpoints is keyed on the Mini

    Program''s AppID and AppSecret, passed as query parameters. Subsequent

    business APIs (template messages, content moderation, analytics, QR codes,

    logistics, etc.) require the `access_token` obtained from

    `auth.getAccessToken`.

    '
  version: 1.0.0
  contact:
    name: WeChat Developer Community
    url: https://developers.weixin.qq.com/community/
  license:
    name: Proprietary
servers:
- url: https://api.weixin.qq.com
  description: WeChat production API
tags:
- name: User Information
  description: User identity (UnionID) lookups.
paths:
  /wxa/getpaidunionid:
    get:
      tags:
      - User Information
      summary: auth.getPaidUnionId
      description: 'Retrieve a user''s UnionID after they have completed a WeChat Pay

        transaction in the Mini Program. Requires either `openid` plus

        `transaction_id`, or `openid` plus `mch_id` and `out_trade_no`.

        '
      operationId: getPaidUnionId
      parameters:
      - in: query
        name: access_token
        required: true
        schema:
          type: string
        description: Application access token from `auth.getAccessToken`.
      - in: query
        name: openid
        required: true
        schema:
          type: string
        description: The user's openid in the Mini Program.
      - in: query
        name: transaction_id
        schema:
          type: string
        description: WeChat Pay transaction id (optional if `mch_id` + `out_trade_no` are supplied).
      - in: query
        name: mch_id
        schema:
          type: string
        description: WeChat Pay merchant id (used with `out_trade_no`).
      - in: query
        name: out_trade_no
        schema:
          type: string
        description: Merchant-side order number (used with `mch_id`).
      responses:
        '200':
          description: Paid UnionID result.
          content:
            application/json:
              schema:
                oneOf:
                - type: object
                  properties:
                    unionid:
                      type: string
                      description: Cross-application UnionID for the paying user.
                    errcode:
                      type: integer
                    errmsg:
                      type: string
                - $ref: '#/components/schemas/WeChatError'
components:
  schemas:
    WeChatError:
      type: object
      description: Standard WeChat API error envelope.
      properties:
        errcode:
          type: integer
          description: Numeric WeChat error code; `0` indicates success.
        errmsg:
          type: string
          description: Human-readable error message.
externalDocs:
  description: WeChat Mini Program Server API
  url: https://developers.weixin.qq.com/miniprogram/en/dev/api-backend/