Filtering tree nodes in Angular Treeview component

28 Sep 202312 minutes to read

You can filter the tree nodes based on their text using the DataManager plugin and the fields property of the TreeView.

The following code example demonstrates how to filter the tree nodes in a TreeView.

app.component.ts

import {FieldsSettingsModel, TreeViewComponent} from "@syncfusion/ej2-angular-navigations"
import {MaskedTextBoxComponent} from "@syncfusion/ej2-angular-inputs"
import { Component, Inject, ViewChild } from '@angular/core';
import { DataManager, Query, ReturnOption, Predicate } from '@syncfusion/ej2-data';

/**
 * Filtering tree nodes sample
 */
@Component({
    selector: 'app-container',
    template: `<div id='treeparent'><ejs-maskedtextbox #maskObj id="search" (change)="searchNodes($event)"></ejs-maskedtextbox><ejs-treeview #treeviewObj id="default" [fields]='field'></ejs-treeview></div>`
})
export class AppComponent {

    @ViewChild("treeviewObj") listTreeObj?: TreeViewComponent;

    @ViewChild("maskObj") maskObj?: MaskedTextBoxComponent;

    // list data source for TreeView component
    public localData: Object[] = [
        { id: 1, name: "Australia", hasChild: true },
        { id: 2, pid: 1, name: "New South Wales" },
        { id: 3, pid: 1, name: "Victoria" },
        { id: 4, pid: 1, name: "South Australia" },
        { id: 6, pid: 1, name: "Western Australia" },
        { id: 7, name: "Brazil", hasChild: true },
        { id: 8, pid: 7, name: "Paraná" },
        { id: 9, pid: 7, name: "Ceará" },
        { id: 10, pid: 7, name: "Acre" },
        { id: 11, name: "China", hasChild: true },
        { id: 12, pid: 11, name: "Guangzhou" },
        { id: 13, pid: 11, name: "Shanghai" },
        { id: 14, pid: 11, name: "Beijing" },
        { id: 15, pid: 11, name: "Shantou" },
        { id: 16, name: "France", hasChild: true },
        { id: 17, pid: 16, name: "Pays de la Loire" },
        { id: 18, pid: 16, name: "Aquitaine" },
        { id: 19, pid: 16, name: "Brittany" },
        { id: 20, pid: 16, name: "Lorraine" },
        { id: 21, name: "India", hasChild: true },
        { id: 22, pid: 21, name: "Assam" },
        { id: 23, pid: 21, name: "Bihar" },
        { id: 24, pid: 21, name: "Tamil Nadu" },
        { id: 25, pid: 21, name: "Punjab" }
    ];

    // Mapping TreeView fields property with data source properties
    public field:Object = { dataSource: this.localData, id: 'id', parentID: 'pid', text: 'name', hasChildren: 'hasChild', expanded: "expanded" }

   //Change the dataSource for TreeView
    public changeDataSource(data: Object[]) {
        (this.listTreeObj as TreeViewComponent).fields = {
            dataSource: data, id: 'id', text: 'name',parentID: 'pid', hasChildren: 'hasChild'
        } as FieldsSettingsModel;
    }

    //Filtering the TreeNodes
    public searchNodes(args: any) {
        let _text = this.maskObj?.element.value;
        let predicats = [], _array = [], _filter = [];
        if (_text == "") {
            this.changeDataSource(this.localData);
        }
        else {
            let predicate = new Predicate('name', 'startswith', _text as string, true);
            let filteredList = new DataManager(this.localData).executeLocal(new Query().where(predicate));
            console.log(filteredList)
            for (let j = 0; j < filteredList.length; j++) {
                _filter.push((filteredList as any)[j]["id"]);
                let filters = this.getFilterItems(filteredList[j], this.localData);
                for (let i = 0; i < filters.length; i++) {
                    if (_array.indexOf(filters[i]) == -1 && filters[i] != null) {
                        _array.push(filters[i]);
                        predicats.push(new Predicate('id', 'equal', filters[i] as any, false));
                    }
                }
            }
            if (predicats.length == 0) {
                this.changeDataSource([]);
            } else {
                let query = new Query().where(Predicate.or(predicats));
                let newList = new DataManager(this.localData).executeLocal(query);
                this.changeDataSource(newList);
                let proxy = this;
                setTimeout(function (this: any) {
                    proxy.listTreeObj?.expandAll();
                }, 100);
            }
        }
    }

    //Find the Parent Nodes for corresponding childs
    public getFilterItems(fList: Object | any, list: Object[]): Object[] {
        let nodes = [];
        nodes.push(fList["id"] as any);
        let query2 = new Query().where('id', 'equal', fList["pid"], false);
        let fList1 = new  DataManager(list).executeLocal(query2);
        if (fList1.length != 0) {
            let pNode = this.getFilterItems(fList1[0], list);
            for (let i = 0; i < pNode.length; i++) {
                if (nodes.indexOf(pNode[i]) == -1 && pNode[i] != null)
                    nodes.push(pNode[i]);
            }
            return nodes;
        }
        return nodes;
    }
}

app.module.ts

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';
import { MaskedTextBoxModule } from '@syncfusion/ej2-angular-inputs';
/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,FormsModule,TreeViewModule,MaskedTextBoxModule 
    ],
    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);