Wechat applets cloud development

Start from 0 using applets cloud development

1.1. Initialization of the cloud development environment

// app.js
  onLaunch: function () {
    // The cloud development environment is initialized
    wx.cloud.init({
      env: 'cloud1-1gklnc7n550025ef' // Cloud development environment ID})},Copy the code

1.2. Add, delete, modify and check the database

The GET method queries data
Where Queries the data that meets the conditions
Doc Queries a single piece of data
The add method adds new data
The update method modifies data
Remove Deletes a single piece of data

// 1. Get the database reference
const db = wx.cloud.database()
// 2. Construct a query statement
The collection method gets a reference to a collection
The where method passes in an object, and the database returns a JSON document whose fields are equal to the specified values in the collection. The API also supports advanced query conditions (such as greater than, less than, in, etc.), as described in the documentation view support list
The get method triggers a network request to fetch data from the database
db.collection('books').where({
  publishInfo: {
    country: 'United States'
  }
}).get({
  success: function(res) {
  / / output [{" title ":" The Catcher in The Rye ",...}]
  console.log(res)
 }
})


// index.js

// Query operation

// The traditional way
			wx.cloud.database().collection('recommend_food')
			.get({
				success(res){
					console.log('Request successful',res)
				},
				fail(err){
					console.log('Request failed',err)
				}
			})

// es6
			wx.cloud.database().collection('recommend_food')
				.get().then(res= > {
					console.log('Request successful',res)
				},err= >{
					console.log('Request failed',err)
				})
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1.3. The storage

Cloud development provides storage space and cloud download capability for uploading files to the cloud with permission management. Developers can use the cloud storage function through apis on the small program side and cloud function side.

// Let the user select an image
wx.chooseImage({
  success: chooseResult= > {
    // Upload the image to cloud storage space
    wx.cloud.uploadFile({
      // Specify the cloud path to upload
      cloudPath: 'my-photo.png'.// Specifies the applets temporary file path for the file to upload
      filePath: chooseResult.tempFilePaths[0].// Successful callback
      success: res= > {
        console.log('Upload successful', res)
      },
    })
  },
})
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1.4. Cloud function

A cloud function is a piece of code that runs in the cloud and can be written in a development tool, uploaded and deployed with one click, without the need to manage a server. An API specifically for cloud function calls is provided within the applets. Developers can use the getWXContext method provided by WX-server-SDK in the cloud function to obtain the context of each call (appID, OpenID, etc.), and obtain the natural trusted user login state (OpenID) without maintaining complex authentication mechanism.

Writing cloud functions
One-click Deployment of cloud functions (cloud functions need to be redeployed after changes)

Calling the cloud function

// Cloud function entry file
const cloud = require('wx-server-sdk')

cloud.init()

// Cloud function entry function
exports.main = async (event, context) => {
  const wxContext = cloud.getWXContext()

  return {
    event,
    openid: wxContext.OPENID,
    appid: wxContext.APPID,
    unionid: wxContext.UNIONID,
  }
}
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1.41. Initialize the environment of the cloud function

Create a folder named Cloud that is the equivalent of Pages
In project.config.json, set the cloud function to cloud.
```
"cloudfunctionRoot": "/cloud"
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```
The cloud folder icon appears as a cloud representing success

1.42. Cloud function calls

Create the Node.js cloud function

Write the cloud function entry function

exports.main = async (event, context) => {
  return cloud.database().collection('recommend_food')
			.get()
}
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Calling the cloud function

// Cloud function call
wx.cloud.callFunction({
	name: 'getData',
}).then(res= > {
	console.log('succes',res)
	this.setData({
		openid: res.result.openid
	})
},err= > {
	console.log('error',err)
})
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1.43. Multiple cloud development environment issues

Specify the cloud development environment you want to use in the cloud function

Use the DYNAMIC_CURRENT_ENV constant

cloud.init({
  env: cloud.DYNAMIC_CURRENT_ENV
})
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Wechat applets cloud development