WeChat small program data pre-pull

Data pre-pull

Pre-pull can pull business data from third-party servers in advance through WeChat background when the small program starts cold, and can render the page faster when the code package is loaded, reducing the user's waiting time, thus increasing the speed of opening the small program.

Use the process

1. Configure the data download address

Log in to the small program MP management background, go to the settings -gt; development settings -gt; data preload, click on on, fill in the data download address, only httpS support.

2. Set up TOKEN

The first time you start a small program, call wx.setBackgroundFetchToken() to set up a TOKEN string that can be related to the user state and will be brought with you when a subsequent WeChat client requests from the developer server, making it easy to verify the legitimacy of the request to the latter.

Example:

App({
  onLaunch() {
    wx.setBackgroundFetchToken({
      token: 'xxx'
    })
  }
})

3. WeChat client pulls data in advance

When the user opens the gadget, weChat servers initiate an HTTP GET request to the developer server (the data download address configured above) that contains the query parameters as follows, and when the data is obtained, the entire HTTP body is cached locally.

The query parameter is processed using urlencode

Token and code exist only one and are used to identify the user.

The data type returned by the developer server interface should be a string and should be no larger than 256KB in size, otherwise the data will not be cached

4. Read the data

When the user starts the program, call wx.getBackgroundFetchData() to get the data that has been cached locally.

Example:

App({
  onLaunch() {
    wx.getBackgroundFetchData({
      fetchType: 'pre',
      success(res) {
        console.log(res.fetchedData) // 缓存数据
        console.log(res.timeStamp) // 客户端拿到缓存数据的时间戳
        console.log(res.path) // 页面路径
        console.log(res.query) // query 参数
        console.log(res.scene) // 场景值
      }
    })
  }
})

Debug method

In order to facilitate debugging data pre-pull, the tool provides the following debugging capabilities to developers.