The applet reads more than 20 data, and the cloud function reads more than 100 restrictions

Students who have seen the basic course of stone Geyun development must know , Request data directly in the applet, and you can only return at most 20 Data , The requested data in the cloud function can only return at most 100 Data , If you want to break through this limit , The best way is to do paging , Of course, I also teach you in Cloud Development Foundation . But there is a need to limit , What if we want to get all the data stored in the database at one time , For example, there are... In the database 1000 Data , We want to get it all at once , How do you do that ？？？

Today, let's teach you how to return up to... Each time through the cloud function 100 Restrictions on .

One , Cloud function breakthrough 100 Restrictions on

As shown in the figure above , my num There are 103 Data , If you follow the previous pagination idea , It's two requests , First request 1-100 strip , Second request 101-103 strip . So we can get it 103 Data , But it takes two requests , How do we do it , Only one request can get this information 103 Data .

1-1, breakthrough 100 Principle of bar

In fact, the principle is the same as our paging principle , It's just that we use for Loop multiple requests , Then combine the multiple requests together , Then return the combined data all at once . In this way, all data is obtained through one request .

1-2, Code implementation

The code here is written in the cloud function , I'll write down the operation steps in the notes .

As shown in the figure above , We only need to go through three steps , You can get everything 103 Bar data .

So we can pass a request , Got all the data . Does it feel very simple . Here the code is posted to everyone .

//  Cloud function entry file 
const cloud = require('wx-server-sdk')
//  Cloud development environment initialization 
cloud.init({env: cloud.DYNAMIC_CURRENT_ENV})
exports.main = async (event, context) => {
  const db = cloud.database()
  // 1, Total number of acquired data 
  let count = await db.collection('num').count()
  count = count.total
  // 2, adopt for Loop multiple requests , And put the data requested many times into an array 
  let all = []
  for (let i = 0; i < count; i += 100) { // Set the amount of data obtained each time 
    let list = await db.collection('num').skip(i).get()
    all = all.concat(list.data);
  }
  // 3, Return all the assembled data at one time 
  return all;
}

1-3, matters needing attention

The data returned by a cloud function cannot exceed 1M, If you need more than 1M, You need to use the data query on the applet side 20 strip 20 The of bars are combined . So if you want to return a lot of data at once , You can consider requesting the database directly in the applet , Then I do 20 strip 20 Assembly of bar .

I will also teach you how to assemble in small programs .

Two , Applet directly requests database breakthrough 20 strip

2-1, Turn on async and await

We won't talk about the principle here , It's as like as two peas. , But in small programs await You need to do the following simple operations , You can also read another article of mine .

《 Used in applet async and await The mutation step is synchronization , Solve the problem of callback to hell 》

It seems that the latest version of the applet developer tool supports async and await The method , It seems that it's OK not to check enhanced compilation . But for safety's sake , It's better to check enhanced compilation .

2-2, Authority modification

Get the data in the database directly from the applet , Remember to change the permissions of the collection

2-3, Code implementation

Careful students can certainly see it , The above code is basically as like as two peas in our cloud function .

Here we have perfectly broken through the limitation of small programs , Return any number of data we want .

Later, we will summarize more small program knowledge points for you , Welcome to your attention , Welcome to leave a message .