Paging query in applet

Daily small programs often need the function of paging query , In this article, we will explain how to realize the function of paging query in low code . Develop your own paging function , You can refer to the official method first

Paging queries usually require input and output parameters , Page numbers are required for entering references 、 The size of each page 、 Sort field name 、 sort order 、 Query criteria .

The total number of entries should be recorded separately 、 Page number 、 The size of each page 、 Record list .

After the input and output parameters are known , Where to write the code ？ Functions such as paging are generally back-end capabilities , Low code tools write back-end code in custom connectors .

Create a custom connector

Log in to the low code console , Click on Create a new custom connector

Enter a name and identification

Click on Create a new... Now

Enter a name and identification , Intend to select the query list , Type selection custom code

The part that can input code in the interface is our editor for compiling back-end logic code , You can write code directly inside .

Introduction to cloud development

We need to implement the back-end code , In fact, it should conform to the syntax of cloud development , We open the official document of cloud development , find api part

There is a concept to understand , Namely collection. In the document database, the table of our traditional database corresponds to collection, How to find collection Well ？

We can open cloud development cloudbase, Then enter our environment , Find the database

Each set is on the list . With a set, how to write code ？ Here you can refer to the customized code section of the official wechat documentation , Copy the code into the custom code editor

module.exports = async function (params, context) {
    
  const result = await context.database.collection('lcap-data-1TSuH5tum-product_qnniu21-preview').get();

  //  Return the result of this method here , It needs to be mapped with the structure defined by the output parameter 
  return {
    
    records: result.data
  };
};

After the code is written, you need to do method testing , First, you need to add an input parameter , After adding, we can see the implementation results

Pagination implementation ideas

To achieve paging , A total of several fields are required , The first is to find the total number of records , The total number of records we can use count Method to calculate

module.exports = async function (params, context) {
    
  const result = await context.database.collection('lcap-data-1TSuH5tum-product_qnniu21-preview').get();
  const total = await context.database.collection('lcap-data-1TSuH5tum-product_qnniu21-preview').count();
  //  Return the result of this method here , It needs to be mapped with the structure defined by the output parameter 
  return {
    
    total:total.total,
    records: result.data
  };
};

The total number of records has , Not all the results we return every time , You need to filter the data according to the page number transmitted and the number of items displayed on each page

module.exports = async function (params, context) {
    
  const result = await context.database.collection('lcap-data-1TSuH5tum-product_qnniu21-preview').skip(params.pageSize*(params.pageNo-1)).limit(params.pageSize).get();
  const total = await context.database.collection('lcap-data-1TSuH5tum-product_qnniu21-preview').count();
  //  Return the result of this method here , It needs to be mapped with the structure defined by the output parameter 
  return {
    
    total:total.total,
    records: result.data
  };
};

After everything is done, you can click the parameter mapping , To automatically map out parameters

Use connectors

After the paging method is completed, it usually needs to be used in the application , One is that it can be used directly in variables

The other is that it can be bound in the data list

Why customize the paging function

The officially generated paging method can only realize single table business , In actual business, we often need to split tables , However, in the scenario of multi table query, data needs to be displayed , At this time, you must implement paging logic by yourself . In the next part, we will explain how to realize multi table paging query , Coming soon .