Implement multi-level linkage selector effects in WeChat mini programs

To implement the multi-level linkage selector effect in WeChat mini programs, specific code examples are required

With the popularity and development of WeChat mini programs, more and more Developers began to pay attention to the development skills and implementation effects of small programs. Among them, multi-level linkage selector is a common selector effect in small programs, which can provide good user experience and interactive effects. This article will introduce how to implement multi-level linkage selectors in WeChat mini programs and give specific code examples.

Step 1: Create page and layout

First, we need to create a new page to implement the multi-level linkage selector. In the WeChat Developer Tools, select "New File", select "Page", and then fill in the page name and path. In the created page, we need to define the layout and style of the selector.

The sample code is as follows:

<view class="container">
   <picker mode="selector" range="{{pickerData.firstArray}}" bindchange="handleFirstChange">
     <view>{{pickerData.firstArray[pickerData.firstIndex]}}</view>
   </picker>
   <picker mode="selector" range="{{pickerData.secondArray}}" bindchange="handleSecondChange">
     <view>{{pickerData.secondArray[pickerData.secondIndex]}}</view>
   </picker>
   <picker mode="selector" range="{{pickerData.thirdArray}}" bindchange="handleThirdChange">
     <view>{{pickerData.thirdArray[pickerData.thirdIndex]}}</view>
   </picker>
</view>

In the above code, we use three picker components as the basis of the multi-level linkage selector. Each picker component has a range attribute to define Optional data source, and bind the selection change callback function through the bindchange event. In each picker component, we also define a view component to display the currently selected item.

Step 2: Define the data source of the selector

To implement multi-level linkage selectors in the applet, we need to define the data source of the selector. These data sources can be obtained through interfaces or local data, and are organized in a certain format. In this example, we assume that the selector has three levels of selection, and the data sources of each level of selector are firstArray, secondArray and thirdArray respectively.

The sample code is as follows:

Page({
   data: {
      pickerData: {
         firstArray: ["选项一", "选项二", "选项三"],
         secondArray: ["选项A", "选项B", "选项C"],
         thirdArray: ["选项甲", "选项乙", "选项丙"]
      },
      firstIndex: 0,
      secondIndex: 0,
      thirdIndex: 0
   },
   handleFirstChange: function(e) {
      this.setData({
         firstIndex: e.detail.value
      })
   },
   handleSecondChange: function(e) {
      this.setData({
         secondIndex: e.detail.value
      })
   },
   handleThirdChange: function(e) {
      this.setData({
         thirdIndex: e.detail.value
      })
   }
})

In the above code, we define the pickerData object in data, which contains the data source of the three-level selector. At the same time, we also defined three variables to record the currently selected index of each selector. In the callback function when the selector selection changes, we update the corresponding index variable through the setData method.

Step 3: Process the linkage effect of the selector

The last step is to process the linkage effect of the selector. In a multi-level linkage selector, when the previous level selection of the selector changes, the data source of the next level selector needs to be updated according to the selected value to achieve the linkage effect.

The sample code is as follows:

Page({
   data: {
      pickerData: {
         firstArray: ["选项一", "选项二", "选项三"],
         secondArray: [],
         thirdArray: []
      },
      firstIndex: 0,
      secondIndex: 0,
      thirdIndex: 0
   },
   handleFirstChange: function(e) {
      var firstIndex = e.detail.value;
      var firstArray = this.data.pickerData.firstArray;
      var secondArray = this.getSecondArray(firstIndex);
         
      this.setData({
         firstIndex: firstIndex,
         secondArray: secondArray,
         secondIndex: 0,
         thirdArray: [],
         thirdIndex: 0,
      })
   },
   handleSecondChange: function(e) {
      var secondIndex = e.detail.value;
      var firstIndex = this.data.firstIndex;
      var secondArray = this.data.pickerData.secondArray;
      var thirdArray = this.getThirdArray(firstIndex, secondIndex);
      
      this.setData({
         secondIndex: secondIndex,
         thirdArray: thirdArray,
         thirdIndex: 0
      })
   },
   handleThirdChange: function(e) {
      var thirdIndex = e.detail.value;
      this.setData({
         thirdIndex: thirdIndex
      })
   },
   getSecondArray: function(firstIndex) {
      // 根据firstIndex获取对应的secondArray
      // 示例代码省略
   },
   getThirdArray: function(firstIndex, secondIndex) {
      // 根据firstIndex和secondIndex获取对应的thirdArray
      // 示例代码省略
   }
})

In the above code, we define two auxiliary functions getSecondArray and getThirdArray to calculate the data source of the next level selector based on the value of the previous level selector. . The specific implementation of these two functions is omitted, and developers can define them according to actual needs.

Summary

Through the above steps, we can achieve the multi-level linkage selector effect in the WeChat applet. In this example, we create a new page and define three picker components as the basis of the multi-level linkage selector. Next, we completed the implementation of the multi-level linkage selector by defining the data source of the selector and processing the linkage effect of the selector.

Of course, the above example is just an implementation method, and developers can adjust and expand it according to actual needs. I hope this article can provide some help to developers in implementing multi-level linkage selector effects in WeChat mini programs.

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