Select one child in Angular Treeview component
28 Sep 20236 minutes to read
TreeView allows both single and multiple selections. If your application needs to select one child at a time under one specific parent, refer to the following example. Here, you can achieve this in the nodeSelecting
event of TreeView. However, you can reset the selected child and make another selection by pressing Ctrl + selected nodes.
import { Component, Inject, ViewChild } from '@angular/core';
import { TreeViewComponent, NodeSelectEventArgs } from '@syncfusion/ej2-angular-navigations';
/**
* Single child selection at a time
*/
@Component({
selector: 'app-container',
template: `<div id='treeparent'><ejs-treeview #tree id="listtree" allowMultiSelection='allowMultiSelection' [fields]='listfields' (nodeSelecting)="onNodeSelecting($event)"></ejs-treeview></div>`
})
export class AppComponent {
@ViewChild('tree')
public tree?: TreeViewComponent;
// Self-referential list data source for TreeView component
public localData: Object[] = [
{ id: 1, name: 'Parent 1', hasChild: true, expanded: true },
{ id: 2, pid: 1, name: 'Child 1' },
{ id: 3, pid: 1, name: 'Child 2' },
{ id: 4, pid: 1, name: 'Child 3' },
{ id: 7, name: 'Parent 2', hasChild: true, expanded: true },
{ id: 8, pid: 7, name: 'Child 1' },
{ id: 9, pid: 7, name: 'Child 2' },
{ id: 10, pid: 7, name: 'Child 3' },
];
public listfields: Object = { dataSource: this.localData, id: 'id', parentID: 'pid', text: 'name', hasChildren: 'hasChild' };
public allowMultiSelection: boolean = true;
public parent?: any; public child?: any;
public count: boolean = false;
public childCount: boolean = false;
// Triggers when you select any node
public onNodeSelecting(args: NodeSelectEventArgs): void {
console.log(args.nodeData);
let id: any = args.nodeData['parentID'];
if (!this.count) {
this.parent = id;
this.count = true;
}
if (!this.childCount){
this.child = args.nodeData['id'];
this.childCount = true
}
if (id != null && id === this.parent) {
let element: HTMLElement = this.tree?.element.querySelector('[data-uid="' + id + '"]') as HTMLElement;
let liElements: any = element.querySelectorAll('ul li');
for (let i: number = 0; i < liElements.length; i++) {
let nodeData: any = this.tree?.getNode(liElements[i]);
if (nodeData.selected && args.action === "select" && this.child !== args.nodeData['id']) {
args.cancel = true;
}
// For unselect the selectedNodes
else if (args.action === "un-select" && this.child === args.nodeData['id']) {
this.childCount = false;
this.child = null;
this.parent = null;
this.count = false;
}
}
} else if (id !== this.parent && id !== null) {
if(args.action == "select"){
args.cancel = true
}
} else if (id === null){
this.childCount = false;
this.child = null;
this.parent = null;
this.count = false
}
}
}
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { TreeViewModule } from '@syncfusion/ej2-angular-navigations';
/**
* Module
*/
@NgModule({
imports: [
BrowserModule,FormsModule,TreeViewModule
],
declarations: [AppComponent],
bootstrap: [AppComponent]
})
export class AppModule { }
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';
import 'zone.js';
enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);