The cascading MultiSelect is a series of MultiSelect, where the value of one MultiSelect depends
upon another’s value. This can be configured by using the change event of the parent MultiSelect.
Within that change event handler, data has to be loaded to the child MultiSelect based on the selected
value of the parent MultiSelect.
The following example, shows the cascade behavior of country, state, and city
MultiSelect. Here, the dataBind method is used to reflect the property changes immediately
to the MultiSelect.
import { Component, ViewChild } from '@angular/core';
import { MultiSelectComponent } from '@syncfusion/ej2-angular-dropdowns';
import { Query, DataManager, Predicate } from '@syncfusion/ej2-data';
@Component({
selector: 'app-root',
// specifies the template path for MultiSelect component
templateUrl: `./cascading.html`
})
export class AppComponent {
constructor() {
}
//define the country MultiSelect data
public countryData: { [key: string]: Object }[] = [
{ countryName: 'Australia', countryId: '2' },
{ countryName: 'United States', countryId: '1' }
];
//define the state MultiSelect data
public stateData: { [key: string]: Object }[] = [
{ stateName: 'New York', countryId: '1', stateId: '101' },
{ stateName: 'Virginia ', countryId: '1', stateId: '102' },
{ stateName: 'Tasmania ', countryId: '2', stateId: '105' }
];
//define the city MultiSelect data
public cityData: { [key: string]: Object }[] = [
{ cityName: 'Albany', stateId: '101', cityId: 201 },
{ cityName: 'Beacon ', stateId: '101', cityId: 202 },
{ cityName: 'Emporia', stateId: '102', cityId: 206 },
{ cityName: 'Hampton ', stateId: '102', cityId: 205 },
{ cityName: 'Hobart', stateId: '105', cityId: 213 },
{ cityName: 'Launceston ', stateId: '105', cityId: 214 }
];
// maps the appropriate column to fields property for country MultiSelect
public countryFields: Object = { text: 'countryName', value: 'countryId' };
// maps the appropriate column to fields property for state MultiSelect
public stateFields: Object = { text: 'stateName', value: 'stateId' };
// maps the appropriate column to fields property for city MultiSelect
public cityFields: Object = { text: 'cityName', value: 'cityId' };
//set the placeholder to country MultiSelect input
public countryWatermark: string = "Select countries";
//set the placeholder to state MultiSelect input
public stateWatermark: string = "Select states";
//set the placeholder to city MultiSelect input
public cityWatermark: string = "Select cities";
@ViewChild('country')
public countryObj: MultiSelectComponent;
@ViewChild('state')
public stateObj: MultiSelectComponent;
@ViewChild('city')
public cityObj: MultiSelectComponent;
public countryChange(): void {
//Query the data source based on country MultiSelect selected value
let pred:Predicate;
if(this.countryObj.value)
for(var d=0;d<this.countryObj.value.length;d++){
if(pred)
pred = pred.or("countryId",'equal',this.countryObj.value[d]);
else{
pred=new Predicate("countryId",'equal',this.countryObj.value[d]);
}
}
else{
this.stateObj.setProperties({enabled:false,values:[]});
this.cityObj.setProperties({enabled:false,values:[]});
return;
}
// enable the state MultiSelect
this.stateObj.setProperties({query:new Query().where(pred),enabled:true,values:[]});
//clear the existing selection in city MultiSelect
this.cityObj.setProperties({enabled:false,values:[]});
}
public stateChange(): void {
//Query the data source based on country MultiSelect selected value
let pred:Predicate,temp:any;
if(this.stateObj.value)
for(var d=0;d<this.stateObj.value.length;d++){
if(pred)
pred = pred.or("stateId",'equal',this.stateObj.value[d]);
else{
pred=new Predicate("stateId",'equal',this.stateObj.value[d]);
}
}
else{
this.cityObj.setProperties({enabled:false,values:[]});
return;
}
this.cityObj.setProperties({query:new Query().where(pred),enabled:true,values:[]});
}
}import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { MultiSelectModule } from '@syncfusion/ej2-angular-dropdowns';
/**
* Module
*/
@NgModule({
imports: [
BrowserModule,FormsModule, MultiSelectModule
],
declarations: [AppComponent],
bootstrap: [AppComponent]
})
export class AppModule { }import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';
enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);<!DOCTYPE html>
<html lang="en">
<head>
<title>Angular MultiSelect</title>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="description" content="Angular UI Controls" />
<meta name="author" content="Syncfusion" />
<link href="index.css" rel="stylesheet" />
<link href="//cdn.syncfusion.com/ej2/20.1.57/ej2-dropdowns/styles/material.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/core-js/2.4.1/core.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/zone.js/0.6.25/zone.min.js"></script>
<script src="https://unpkg.com/reflect-metadata@0.1.3"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
<script src="systemjs.config.js"></script>
</head>
<body>
<div id="wrapper" style='margin-top: 20px'>
<div id='content' style="margin: 50px auto 0; width:250px;">
<br>
<ejs-multiselect #country id="country" [dataSource]="countryData" [fields]="countryFields" [changeOnBlur]= "false" (change)="countryChange($event)" [placeholder]="countryWatermark"></ejs-multiselect>
<div class="padding-top">
<ejs-multiselect #state id="state" [dataSource]="stateData" [fields]="stateFields" [changeOnBlur] = "false" (change)="stateChange($event)" [placeholder]="stateWatermark" [enabled]="false"></ejs-multiselect>
</div>
<div class="padding-top">
<ejs-multiselect #city id="city" [dataSource]="cityData" [fields]="cityFields" [placeholder]="cityWatermark" [enabled]="false"></ejs-multiselect>
</div>
</div>
</div>
</body>
</html>