Select one child in React Treeview component

30 Jan 202313 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.

index.jsx

import * as ReactDOM from 'react-dom';
import * as React from 'react';
import { TreeViewComponent } from '@syncfusion/ej2-react-navigations';
function App() {
    // Self-referential list data source for TreeView component
    let localData = [
        { 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' },
    ];
    let field = { dataSource: localData, id: 'id', parentID: 'pid', text: 'name', hasChildren: 'hasChild' };
    let allowMultiSelection = true;
    let loadOnDemand = false;
    let parent;
    let child;
    let count = false;
    let childCount = false;
    let treeObj;
    // Triggers when you select any node
    function onNodeSelecting(args) {
        let id = args.nodeData.parentID;
        if (!count) {
            parent = id;
            count = true;
        }
        if (!childCount) {
            child = args.nodeData.id;
            childCount = true;
        }
        if (id != null && id === parent) {
            let element = treeObj.element.querySelector('[data-uid="' + id + '"]');
            let liElements = element.querySelectorAll('ul li');
            for (let i = 0; i < liElements.length; i++) {
                let nodeData = treeObj.getNode(liElements[i]);
                if (nodeData.selected && args.action === "select" && child !== args.nodeData.id) {
                    args.cancel = true;
                }
                // For unselect the selectedNodes
                else if (args.action === "un-select" && child === args.nodeData.id) {
                    childCount = false;
                    child = null;
                    parent = null;
                    count = false;
                }
            }
        }
        else if (id !== parent && id !== null) {
            if (args.action == "select") {
                args.cancel = true;
            }
        }
        else if (id === null) {
            childCount = false;
            child = null;
            parent = null;
            count = false;
        }
    }
    return (<div className='control-pane'>
          <div className='control-section'>
            <div className='control_wrapper'>
              {/* Render TreeView */}
              <TreeViewComponent fields={field} loadOnDemand={loadOnDemand} nodeSelecting={onNodeSelecting.bind(this)} allowMultiSelection={allowMultiSelection} ref={(treeview) => { treeObj = treeview; }}/>
            </div>
          </div>
        </div>);
}
export default App;
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

import * as ReactDOM from 'react-dom';
import * as React from 'react';
import {TreeViewComponent, NodeSelectEventArgs } from '@syncfusion/ej2-react-navigations';

function App() {
  
  // Self-referential list data source for TreeView component
  let localData: { [key: string]: 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' },
  ];
  let field: Object = { dataSource: localData, id: 'id', parentID: 'pid', text: 'name', hasChildren: 'hasChild' };
  let allowMultiSelection: boolean = true;
  let loadOnDemand: boolean = false;
  let parent: any; let child: any;
  let count: boolean = false;
  let childCount: boolean = false;
  let treeObj: TreeViewComponent;
  // Triggers when you select any node
  function onNodeSelecting(args: NodeSelectEventArgs): void {
    let id: any = args.nodeData.parentID;
    if (!count) {
       parent = id;
       count = true;
    }
    if (!childCount){
       child = args.nodeData.id;
       childCount = true
    }
    if (id != null && id === parent) {
      let element: HTMLElement = treeObj.element.querySelector('[data-uid="' + id + '"]');
      let liElements: any = element.querySelectorAll('ul li');
      for (let i: number = 0; i < liElements.length; i++) {
        let nodeData: any = treeObj.getNode(liElements[i]);
        if (nodeData.selected && args.action === "select" && child !== args.nodeData.id) {
          args.cancel = true;
        }
        // For unselect the selectedNodes
        else  if (args.action === "un-select" && child === args.nodeData.id) {
          childCount = false;
          child = null;
          parent = null;
          count = false;
        }
      }
    } else if (id !== parent && id !== null) {
        if(args.action == "select"){
          args.cancel = true
        }
    } else if (id === null){
       childCount = false;
          child = null;
          parent = null;
          count = false
    }
  }
    return (
      <div className = 'control-pane'>
          <div className='control-section'>
            <div className='control_wrapper'>
              {/* Render TreeView */}
              <TreeViewComponent fields={field} loadOnDemand={loadOnDemand} nodeSelecting={onNodeSelecting.bind(this)} allowMultiSelection={allowMultiSelection}  ref={(treeview) => { treeObj = treeview as TreeViewComponent; }}/>
            </div>
          </div>
        </div>
      )
}
export default App;
ReactDOM.render(<App />, document.getElementById('sample'));