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Salesforce LWC学习(六) @salesforce & lightning/ui*Api Reference
salesforce零基础学习（八十七）Apex 中Picklist类型通过Control 字段值获取Dependent List 值
拥有dependence的picklist在项目中经常出现，我们在项目中需要展示级联的picklist展示。Salesforce lwc中可以通过wire adapter + combobox来实现级联，步骤和代码如下。
1. 在Account中声明两个字段，Controlling_Picklist__c以及Master_Picklist__c两个picklist字段，其中Master_Picklist作为主
2. 通过getObjectInfo的wire adapter获取record type等信息，然后通过getPicklistValuesByRecordType可以获取表中所有的picklist的metadata信息。
这里先可以看一下picklist metadata信息如下。我们在第二个链接中可以看到dependence picklist通过valid for进行了关联，所以我们成功的关键也是通过valid for进行了关联。
{
"picklistFieldValues": {
"Controlling_Picklist__c": {
"controllerValues": {
"M2": 1,
"M3": 2,
"M1": 0
},
"values": [
{
"validFor": [
0
],
"label": "M1->D1",
"value": "M1->D1",
"attributes": null
},
{
"validFor": [
0
],
"label": "M1->D2",
"value": "M1->D2",
"attributes": null
},
{
"validFor": [
1
],
"label": "M2->D1",
"value": "M2->D1",
"attributes": null
},
{
"validFor": [
1
],
"label": "M2->D2",
"value": "M2->D2",
"attributes": null
}
],
"defaultValue": null,
"url": "/services/data/v47.0/ui-api/object-info/Account/picklist-values/0120I000000OaFoQAK/Controlling_Picklist__c"
},
"Master_Picklist__c": {
"controllerValues": {},
"values": [
{
"validFor": [],
"label": "M1",
"value": "M1",
"attributes": null
},
{
"validFor": [],
"label": "M2",
"value": "M2",
"attributes": null
},
{
"validFor": [],
"label": "M3",
"value": "M3",
"attributes": null
}
],
"defaultValue": null,
"url": "/services/data/v47.0/ui-api/object-info/Account/picklist-values/0120I000000OaFoQAK/Master_Picklist__c"
}
}
}
代码实现如下：
dependentPicklistInLWC.html：使用combobox展示两个下拉列表，设置相关的事件处理
<template>
<lightning-card title="Custom Dependent Picklist using Lightning Web Components"><br/>
<lightning-layout>
<lightning-layout-item padding="around-small" flexibility='auto' size='6'>
<lightning-combobox label="master picklist"
name="master"
onchange={handleMasterPicklistChange}
options={masterValues}
placeholder="--None--"
value={selectedMasterValue}></lightning-combobox>
</lightning-layout-item>
<lightning-layout-item padding="around-small" flexibility='auto' size='6'>
<lightning-combobox label="controlling picklist"
name="controlling"
onchange={handleControllingPicklistChange}
options={controllingValues}
placeholder="--None--"
value={selectedControllingValue}
></lightning-combobox>
</lightning-layout-item> </lightning-layout>
</lightning-card>
</template>
dependentPicklistInLWC.js：使用getObjectInfo以及getPicklistValuesByRecordType去进行Picklist的select option的构造，这里的关键就是理解好valid for
/* eslint-disable no-console */
import { LightningElement, wire, track } from 'lwc';
import { getPicklistValuesByRecordType } from 'lightning/uiObjectInfoApi';
import { getObjectInfo } from 'lightning/uiObjectInfoApi';
import ACCOUNT_OBJECT from '@salesforce/schema/Account'; export default class DependentPickListInLWC extends LightningElement { //存储controlling picklist的所有的值
@track masterValues = [];
//存储dependent picklist的所有的值
@track controllingValues = [];
//选择的controlling picklist 的值
@track selectedMasterValue;
//选择的dependent picklist的值
@track selectedControllingValue; @track error;
//用来记录master picklist中的 value -> valid for的列表集合
master2ValidForValues;
//用来记录controlling picklist的value以及valid for等信息的列表集合
controllingValuesWithValidFor = []; // 获取account 的schema info
@wire(getObjectInfo, { objectApiName: ACCOUNT_OBJECT })
objectInfo; // 获取 control picklist的值并且组装dependent picklist
@wire(getPicklistValuesByRecordType, { objectApiName: ACCOUNT_OBJECT, recordTypeId: '$objectInfo.data.defaultRecordTypeId'})
countryPicklistValues({error, data}) {
if(data) {
this.error = null;
let masterOptions = []; data.picklistFieldValues.Master_Picklist__c.values.forEach(key => {
masterOptions.push({
label : key.label,
value: key.value
})
}); this.masterValues = masterOptions; let controllingOptions = []; this.master2ValidForValues = data.picklistFieldValues.Controlling_Picklist__c.controllerValues;
//用来记录controlling picklist的value以及valid for等信息的列表集合 Picklist values
this.controllingValuesWithValidFor = data.picklistFieldValues.Controlling_Picklist__c.values;
this.controllingValuesWithValidFor.forEach(key => {
controllingOptions.push({
label : key.label,
value: key.value
})
}); this.controllingValues = controllingOptions;
}
else if(error) {
this.error = JSON.stringify(error);
}
} handleMasterPicklistChange(event) {
//set selected master Value
this.selectedMasterValue = event.target.value;
this.selectedControllingValue = '';
let controllingList = []; if(this.selectedMasterValue) {
//通过valid for进行mapping，匹配的放进controlling list中
this.controllingValuesWithValidFor.forEach(conValues => {
if(conValues.validFor.some(item => item === this.master2ValidForValues[this.selectedMasterValue])) {
controllingList.push({
label: conValues.label,
value: conValues.value
})
}
}) this.controllingValues = controllingList;
}
} handleControllingPicklistChange(event) {
this.selectedControllingValue = event.target.value;
}
}
效果展示：当选择了左侧的master以后，右侧的controlling值便会动态改变。
当然，我们使用这个大前提是当前的object支持getObjectInfo等wire adapter，如果不支持我们需要通过后台schema方式去搞定，比如Task/Event对象并不支持，我们就没法通过前端搞定，那样就只能通过第二个链接中的方式去从后台去构建进行获取。
总结：篇中主要介绍了可以使用wire adapter情况下dependence picklist的实现。篇中有错误地方欢迎指出，有不懂的欢迎留言。
