auth-wechat-miniprogram

name: auth-wechat-miniprogram
description: Complete guide for WeChat Mini Program authentication with CloudBase - native login, user identity, and cloud function integration.
alwaysApply: false

When to use this skill

Use this skill for WeChat Mini Program (小程序) authentication in a CloudBase project.

Use it when you need to:

• Implement WeChat Mini Program login with CloudBase
• Access user identity (openid, unionid) in cloud functions
• Understand how WeChat authentication integrates with CloudBase
• Build Mini Program features that require user identification

Key advantage: WeChat Mini Program authentication with CloudBase is seamless and automatic - no complex OAuth flows needed. When a Mini Program calls a cloud function, the user's openid is automatically injected and verified by WeChat.

Do NOT use for:

• Web-based WeChat login (use the CloudBase Web Auth skill at skills/auth-web-skill)
• Server-side auth with Node SDK (use the CloudBase Node Auth skill at skills/auth-nodejs-skill)
• Non-WeChat authentication methods (use appropriate auth skills)

How to use this skill (for a coding agent)

1. Confirm CloudBase environment

2. Ask the user for:

   • env – CloudBase environment ID
   • Confirm the Mini Program is linked to the CloudBase environment

3. Understand the authentication flow

4. WeChat Mini Program authentication is native and automatic
5. No explicit login API calls needed in most cases
6. User identity is automatically available in cloud functions

7. CloudBase handles all authentication verification

8. Pick a scenario from this file

9. For basic user identity in cloud functions, use Scenario 2
10. For Mini Program initialization, use Scenario 1
11. For calling a cloud function from the Mini Program and receiving user identity, use Scenario 3

12. For testing authentication, use Scenario 4

13. Follow CloudBase API shapes exactly

14. Use wx-server-sdk in cloud functions
15. Use wx.cloud in Mini Program client code

16. Treat method names and parameter shapes in this file as canonical

17. If you're unsure about an API

18. Consult the official CloudBase Mini Program documentation
19. Only use methods that appear in official documentation

Core concepts

How WeChat Mini Program authentication works with CloudBase

1. Automatic authentication:
2. When a Mini Program user calls a cloud function, WeChat automatically injects the user's identity
3. No need for complex OAuth flows or token management

4. CloudBase verifies the authenticity of the identity

5. User identifiers:

6. OPENID – Unique identifier for the user in this specific Mini Program
7. APPID – The Mini Program's App ID

8. UNIONID – (Optional) Unique identifier across all apps under the same WeChat Open Platform account

   • Only available when the Mini Program is bound to a WeChat Open Platform account
   • Useful for identifying the same user across multiple Mini Programs or Official Accounts

9. Security:

10. The openid, appid, and unionid are verified and trustworthy
11. WeChat has already completed authentication

12. Developers can directly use these identifiers without additional verification

13. No explicit login required:

14. Users are automatically authenticated when they use the Mini Program
15. No need to call login APIs in most cases
16. Identity is available immediately in cloud functions

Scenarios – WeChat Mini Program auth patterns

Scenario 1: Initialize CloudBase in Mini Program

Use this in your Mini Program's app.js or entry point:

// app.js
App({
  onLaunch: function () {
    // Initialize CloudBase
    wx.cloud.init({
      env: 'your-env-id',  // Your CloudBase environment ID
      traceUser: true      // Optional: track user access in console
    })
  }
})

Key points:

• Call wx.cloud.init() once when the Mini Program launches
• Set env to your CloudBase environment ID
• traceUser: true enables user access tracking in CloudBase console (optional but recommended)

Scenario 2: Get user identity in a cloud function

Use this when you need to know who is calling your cloud function:

// Cloud function: cloudfunctions/getUserInfo/index.js
const cloud = require('wx-server-sdk')

// Initialize cloud with dynamic environment
cloud.init({
  env: cloud.DYNAMIC_CURRENT_ENV
})

exports.main = async (event, context) => {
  // Get user identity - this is automatically injected by WeChat
  const { OPENID, APPID, UNIONID } = cloud.getWXContext()

  console.log('User identity:', { OPENID, APPID, UNIONID })

  // Use OPENID for user-specific operations
  // For example: query user data, check permissions, etc.

  return {
    openid: OPENID,
    appid: APPID,
    unionid: UNIONID  // May be undefined if not available
  }
}

Key points:

• Use cloud.getWXContext() to get user identity
• OPENID is always available and uniquely identifies the user
• APPID identifies the Mini Program
• UNIONID is only available when:
• The Mini Program is bound to a WeChat Open Platform account
• The user has authorized the Mini Program
• These values are verified and trustworthy - no need to validate them
• Use cloud.DYNAMIC_CURRENT_ENV to automatically use the current environment

Best practices:

• Store OPENID in your database to associate data with users
• Use OPENID for authorization and access control
• Use UNIONID when you need to identify users across multiple Mini Programs or Official Accounts
• Never expose OPENID to other users (it's a private identifier)

Scenario 3: Call cloud function from Mini Program

Use this in your Mini Program to call a cloud function and get user identity:

// In Mini Program page
Page({
  onLoad: function() {
    this.getUserInfo()
  },

  getUserInfo: function() {
    wx.cloud.callFunction({
      name: 'getUserInfo',  // Cloud function name
      data: {},             // Optional parameters
      success: res => {
        console.log('User info from cloud function:', res.result)
        // res.result contains { openid, appid, unionid }

        // Use the user info
        this.setData({
          openid: res.result.openid
        })
      },
      fail: err => {
        console.error('Failed to get user info:', err)
      }
    })
  }
})

Key points:

• Use wx.cloud.callFunction() to call cloud functions
• User identity is automatically passed to the cloud function
• No need to manually send user credentials
• Handle both success and error cases

Scenario 4: Test authentication - Simple test function

Cloud function (cloudfunctions/test/index.js):

const cloud = require('wx-server-sdk')

cloud.init({
  env: cloud.DYNAMIC_CURRENT_ENV
})

exports.main = async (event, context) => {
  // Get verified user identity - automatically injected by WeChat
  const { OPENID, APPID, UNIONID } = cloud.getWXContext()

  console.log('User identity:', { OPENID, APPID, UNIONID })

  return {
    success: true,
    message: 'Authentication successful',
    identity: {
      openid: OPENID,
      appid: APPID,
      unionid: UNIONID || 'Not available'
    },
    timestamp: new Date().toISOString()
  }
}

Mini Program code:

// pages/index/index.js
Page({
  data: {
    userIdentity: null
  },

  onLoad: function() {
    this.testAuth()
  },

  testAuth: function() {
    console.log('Testing authentication...')

    wx.cloud.callFunction({
      name: 'test',
      success: res => {
        console.log('Authentication test result:', res.result)

        this.setData({
          userIdentity: res.result.identity
        })

        wx.showToast({
          title: 'Auth successful',
          icon: 'success'
        })
      },
      fail: err => {
        console.error('Authentication test failed:', err)
        wx.showToast({
          title: 'Auth failed',
          icon: 'error'
        })
      }
    })
  }
})

Key points:

• No explicit login API call needed
• User identity is automatically available in cloud function
• OPENID is always present and verified
• UNIONID may be undefined if not available
• Use this pattern to verify authentication is working correctly

Best practices

1. Always use cloud.DYNAMIC_CURRENT_ENV

cloud.init({
  env: cloud.DYNAMIC_CURRENT_ENV
})

This ensures the cloud function uses the correct environment automatically.

2. Store OPENID for user identification

• Use OPENID as the primary user identifier
• Store it in your database to associate data with users
• Never expose OPENID to other users

3. Handle UNIONID availability

const { OPENID, UNIONID } = cloud.getWXContext()

if (UNIONID) {
  // User has UNIONID - can be used for cross-app identification
  console.log('UNIONID available:', UNIONID)
} else {
  // UNIONID not available - use OPENID only
  console.log('Using OPENID only:', OPENID)
}

4. Use OPENID for user-specific operations

• Use OPENID to identify and authorize users
• Store OPENID when you need to associate data with users
• Use OPENID in queries to ensure users only access their own data

5. Error handling

Always handle errors when calling cloud functions:

wx.cloud.callFunction({
  name: 'myFunction',
  success: res => {
    // Handle success
  },
  fail: err => {
    console.error('Cloud function error:', err)
    // Show user-friendly error message
    wx.showToast({
      title: 'Operation failed',
      icon: 'error'
    })
  }
})

6. Initialize CloudBase early

Initialize CloudBase in app.js onLaunch:

App({
  onLaunch: function () {
    wx.cloud.init({
      env: 'your-env-id',
      traceUser: true
    })
  }
})

Common patterns

Pattern 1: Get and return user identity

const cloud = require('wx-server-sdk')
cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV })

exports.main = async (event, context) => {
  const { OPENID, APPID, UNIONID } = cloud.getWXContext()

  return {
    openid: OPENID,
    appid: APPID,
    unionid: UNIONID || null
  }
}

Pattern 2: Use OPENID for authorization

const cloud = require('wx-server-sdk')
cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV })

exports.main = async (event, context) => {
  const { OPENID } = cloud.getWXContext()

  // Check if user is authorized
  if (OPENID === event.resourceOwnerId) {
    // User is authorized to access this resource
    return { authorized: true }
  } else {
    return { authorized: false, error: 'Unauthorized' }
  }
}

Pattern 3: Handle UNIONID availability

const cloud = require('wx-server-sdk')
cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV })

exports.main = async (event, context) => {
  const { OPENID, UNIONID } = cloud.getWXContext()

  if (UNIONID) {
    // Can use UNIONID for cross-app user identification
    console.log('User has UNIONID:', UNIONID)
  } else {
    // Fall back to OPENID only
    console.log('Using OPENID only:', OPENID)
  }

  return { openid: OPENID, hasUnionId: !!UNIONID }
}

Summary

WeChat Mini Program authentication with CloudBase is simple and secure:

1. No explicit login needed - authentication is automatic
2. User identity is verified - OPENID, APPID, and UNIONID are trustworthy
3. Easy to use - just call cloud.getWXContext() in cloud functions
4. Secure by default - WeChat handles all authentication verification

Key takeaways:

• Initialize CloudBase with wx.cloud.init() in Mini Program
• Use cloud.getWXContext() to get user identity in cloud functions
• Use OPENID for user identification and authorization
• Handle UNIONID availability appropriately
• No explicit login API calls needed - authentication is automatic

For more complex authentication scenarios or integration with other systems, consider using CloudBase custom login in combination with WeChat authentication.