Data binding in Angular Treegrid component

9 Jan 202313 minutes to read

The TreeGrid uses DataManager, which supports both RESTful JSON data services binding and local JavaScript object array binding. The dataSource property can be assigned either with the instance of DataManager or JavaScript object array collection.
It supports two kinds of data binding method:

  • Local data
  • Remote data

To learn about how to bind local or remote data to Tree Grid, you can check on this video:

Binding with ajax

You can use TreeGrid dataSource property to bind the data source to TreeGrid from external ajax request. In the below code we have fetched the data source from the server with the help of ajax request and provided that to dataSource property by using onSuccess event of the ajax.

import { Component, OnInit,ViewChild } from '@angular/core';
import { Ajax } from '@syncfusion/ej2-base';
import { TreeGridComponent } from '@syncfusion/ej2-angular-treegrid';

@Component({
    selector: 'app-container',
    template: ` <button ejs-button (click)="click()">Bind Data</button>
    <ejs-treegrid #treegrid [dataSource]='data' [treeColumnIndex]='1' parentIdMapping='ParentItem' idMapping='TaskID' [allowPaging]="true" height=240>
        <e-columns>
            <e-column field='TaskID' headerText='Task ID' width='90' textAlign='Right'></e-column>
            <e-column field='TaskName' headerText='Task Name' width='170'></e-column>
            <e-column field='StartDate' headerText='Start Date' width='130' format="yMd" textAlign='Right'></e-column>
            <e-column field='Duration' headerText='Duration' width='80' textAlign='Right'></e-column>
        </e-columns>
                </ejs-treegrid>`
})
export class AppComponent implements OnInit {

    public data: DataManager;
    @ViewChild('treegrid')
    public treegrid: TreeGridComponent;
    ngOnInit(): void {
}
 click(e: any): any{
    let ajax = new Ajax("https://ej2services.syncfusion.com/production/web-services/api/SelfReferenceData","GET");
    let trgrid = this.treegrid;
    ajax.send();
    ajax.onSuccess = function (data: string) {
        trgrid.hideSpinner();
        trgrid.dataSource = JSON.parse(data);
    };
}
}
import { NgModule,ViewChild } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { TreeGridModule } from '@syncfusion/ej2-angular-treegrid';
import { PageService, SortService, FilterService } from '@syncfusion/ej2-angular-treegrid';
import { AppComponent } from './app.component';
import {ButtonModule} from '@syncfusion/ej2-angular-buttons';

/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,
        TreeGridModule,
        ButtonModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent],
    providers: [PageService,
                SortService,
                FilterService]
})
export class AppModule { }
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);

  • If you bind the dataSource from this way, then it acts like a local dataSource. So you cannot perform any server side crud actions.

Handling expandStateMapping

To denotes the expand status of parent row, define the expandStateMapping property of tree grid.

The expandStateMapping property maps the field name in data source, that denotes whether parent record is in expanded or collapsed state and this is useful to renders parent row in expanded or collapsed state based on this mapping property value in data source.

import { Component, OnInit } from '@angular/core';
import { DataManager, UrlAdaptor } from '@syncfusion/ej2-data';
import './App.css';

@Component({
    selector: 'app-container',
    template: `<ejs-treegrid [dataSource]='data' [treeColumnIndex]='1' height='400' hasChildMapping='isParent', idMapping='TaskID' expandStateMapping='IsExpanded' parentIdMapping='ParentValue'>
        <e-columns>
            <e-column field='TaskID' headerText='Task ID' width='90' textAlign='Right'></e-column>
            <e-column field='TaskName' headerText='Task Name' width='180'></e-column>
            <e-column field='Duration' headerText='Duration' width='80' textAlign='Right'></e-column>
        </e-columns>
    </ejs-treegrid>`
})
export class AppComponent implements OnInit {

    public data: DataManager;

    public dataManager: DataManager = new DataManager({
        adaptor: new UrlAdaptor,
        url: "Home/DataSource",
    });

    ngOnInit(): void {
        this.data = this.dataManager;
    }
}

The following code example defines expandStateMapping property at server end.

public ActionResult ExpandStateMapping()
{
  return View();
}

public class TreeData
{
    public static List<TreeData> tree = new List<TreeData>();
    [System.ComponentModel.DataAnnotations.Key]
    public int TaskID { get; set; }
    public string TaskName { get; set; }

    public int Duration { get; set; }
    public int? ParentValue { get; set; }
    public bool? isParent { get; set; }

    public bool IsExpanded { get; set; }
    public TreeData() { }
    public static List<TreeData> GetTree()
    {
        if (tree.Count == 0)
        {
            int root = 0;
            for (var t = 1; t <= 500; t++)
            {
                Random ran = new Random();
                string math = (ran.Next() % 3) == 0 ? "High" : (ran.Next() % 2) == 0 ? "Release Breaker" : "Critical";
                string progr = (ran.Next() % 3) == 0 ? "Started" : (ran.Next() % 2) == 0 ? "Open" : "In Progress";
                root++;
                int rootItem = root;
                tree.Add(new TreeData() { TaskID = rootItem, TaskName = "Parent task " + rootItem.ToString(), isParent = true, IsExpanded = false, ParentValue = null, Duration = ran.Next(1, 50) });
                int parent = root;
                for (var d = 0; d < 1; d++)
                {
                    root++;
                    string value = ((parent + 1) % 3 == 0) ? "Low" : "Critical";
                    int par = parent + 1;
                    progr = (ran.Next() % 3) == 0 ? "In Progress" : (ran.Next() % 2) == 0 ? "Open" : "Validated";
                    int iD = root;
                    tree.Add(new TreeData() { TaskID = iD, TaskName = "Child task " + iD.ToString(), isParent = true, IsExpanded = false, ParentValue = rootItem, Duration = ran.Next(1, 50) });
                    int subparent = root;
                    for (var c = 0; c < 500; c++)
                    {
                        root++;
                        string val = ((subparent + c + 1) % 3 == 0) ? "Low" : "Critical";
                        int subchild = subparent + c + 1;
                        string progress = (ran.Next() % 3) == 0 ? "In Progress" : (ran.Next() % 2) == 0 ? "Open" : "Validated";
                        int childID = root ;
                        tree.Add(new TreeData() { TaskID = childID, TaskName = "sub Child task " + childID.ToString(), isParent = false, IsExpanded = false, ParentValue = subparent, Duration = ran.Next(1, 50) });
                    }
                }
            }
        }
        return tree;
    }
}

You can refer to our Angular Tree Grid feature tour page for its groundbreaking feature representations. You can also explore our Angular Tree Grid example to knows how to present and manipulate data.