Modify data in Angular Drop down list component

27 Sep 20233 minutes to read

When binding the remote data source, by using the actionComplete event, you can modify the result data before passing it to DropDownList.

The following sample demonstrate how to modify the result data.

app.component.ts

import { Component } from '@angular/core';
import { Query, DataManager, ODataV4Adaptor } from '@syncfusion/ej2-data'

@Component({
    selector: 'app-root',
    // specifies the template string for the DropDownList component with change event
    template: `<ejs-dropdownlist id='ddlelement' #samples [dataSource]='data' [fields]='fields' [placeholder]='text' [query]='query' [sortOrder]='sorting' (actionComplete)="actionComplete($event)"></ejs-dropdownlist>`
})
export class AppComponent {
    constructor() {
    }
    //bind the DataManager instance to dataSource property
    public data: DataManager = new DataManager({
            url: 'https://services.odata.org/V4/Northwind/Northwind.svc/',
            adaptor: new ODataV4Adaptor,
            crossDomain: true
        });
    // maps the appropriate column to fields property
    public fields: Object = { text: 'ContactName', value: 'CustomerID' };
    //bind the Query instance to query property
    public query: Query = new Query().from('Customers').select(['ContactName', 'CustomerID']).take(6);
    //set the placeholder to DropDownList input
    public text: string = "Select a customer";
    //sort the result items
    public sorting: string = 'Ascending';
    public actionComplete(e: any): void {
        // initially result contains 6 items
        console.log("Before modified the result: " + e.result.length);
        // remove first 2 items from result.
        e.result.splice(0, 2);
        // now displays the result count is 4.
        console.log("After modified the result: " + e.result.length);
    }
}

app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { DropDownListModule } from '@syncfusion/ej2-angular-dropdowns';
import { ButtonModule } from '@syncfusion/ej2-angular-buttons';
/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,FormsModule, ReactiveFormsModule, DropDownListModule, ButtonModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent]
})
export class AppModule { }

main.ts

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

import 'zone.js';
enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);