Winkelmaterial 7 - Baum

Das <mat-tree>Mit dieser Winkelrichtlinie wird ein Baum mit Materialstil erstellt, um hierachische Daten anzuzeigen.

In diesem Kapitel wird die Konfiguration vorgestellt, die zum Zeichnen eines Baums mit Angular Material erforderlich ist.

Es folgt der Inhalt des modifizierten Moduldeskriptors app.module.ts.

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import {BrowserAnimationsModule} from '@angular/platform-browser/animations';
import {MatTreeModule, MatIconModule, MatButtonModule} from '@angular/material'
import {FormsModule, ReactiveFormsModule} from '@angular/forms';
@NgModule({
   declarations: [
      AppComponent
   ],
   imports: [
      BrowserModule,
      BrowserAnimationsModule,
      MatTreeModule, MatIconModule, MatButtonModule,
      FormsModule,
      ReactiveFormsModule
   ],
   providers: [],
   bootstrap: [AppComponent]
})
export class AppModule { }

Es folgt der Inhalt der geänderten HTML-Hostdatei app.component.html.

<mat-tree [dataSource] = "dataSource" [treeControl] = "treeControl">
   <mat-tree-node *matTreeNodeDef = "let node" matTreeNodeToggle matTreeNodePadding>
      <button mat-icon-button disabled></button>
      {{node.filename}} : {{node.type}}
   </mat-tree-node>
   <mat-tree-node *matTreeNodeDef = "let node;when: hasChild" matTreeNodePadding>
      <button mat-icon-button matTreeNodeToggle [attr.aria-label] = "'toggle ' + node.filename">
         <mat-icon class = "mat-icon-rtl-mirror">
            {{treeControl.isExpanded(node) ? 'expand_more' : 'chevron_right'}}
         </mat-icon>
      </button>
      {{node.filename}}
   </mat-tree-node>
</mat-tree>

Es folgt der Inhalt der geänderten ts-Datei app.component.ts.

import {FlatTreeControl} from '@angular/cdk/tree';
import {Component, Injectable} from '@angular/core';
import {MatTreeFlatDataSource, MatTreeFlattener} from '@angular/material/tree';
import {BehaviorSubject, Observable, of as observableOf} from 'rxjs';
export class FileNode {
   children: FileNode[];
   filename: string;
   type: any;
}
export class FileFlatNode {
   constructor(
      public expandable: boolean, public filename: string, public level: number, public type: any) {}
}
const TREE_DATA = JSON.stringify({
   Documents: {
      angular: {
         src: {
            compiler: 'ts',
            core: 'ts'
         }
      },
      material2: {
         src: {
            button: 'ts',
            checkbox: 'ts',
            input: 'ts'
         }
      }
   }
});
@Injectable()
export class FileDatabase {
   dataChange = new BehaviorSubject<FileNode[]>([]);
   get data(): FileNode[] { return this.dataChange.value; }
   constructor() {
      this.initialize();
   }
   initialize() {
      const dataObject = JSON.parse(TREE_DATA);   
      const data = this.buildFileTree(dataObject, 0);
      this.dataChange.next(data);
   } 
   buildFileTree(obj: {[key: string]: any}, level: number): FileNode[] {
      return Object.keys(obj).reduce<FileNode[]>((accumulator, key) => {
         const value = obj[key];
         const node = new FileNode();
         node.filename = key;
         if (value != null) {
            if (typeof value === 'object') {
               node.children = this.buildFileTree(value, level + 1);
            } else {
               node.type = value;
            }
         }
         return accumulator.concat(node);
      }, []);
   }
}
@Component({
   selector: 'app-root',
   templateUrl: 'app.component.html',
   styleUrls: ['app.component.css'],
   providers: [FileDatabase]
})
export class AppComponent {
   treeControl: FlatTreeControl<FileFlatNode>;
   treeFlattener: MatTreeFlattener<FileNode, FileFlatNode>;
   dataSource: MatTreeFlatDataSource<FileNode, FileFlatNode>;
   constructor(database: FileDatabase) {
      this.treeFlattener = new MatTreeFlattener(this.transformer, this._getLevel,
      this._isExpandable, this._getChildren);
      this.treeControl = new FlatTreeControl<FileFlatNode>(this._getLevel, this._isExpandable);
      this.dataSource = new MatTreeFlatDataSource(this.treeControl, this.treeFlattener);
      database.dataChange.subscribe(data => this.dataSource.data = data);
   }
   transformer = (node: FileNode, level: number) => {
      return new FileFlatNode(!!node.children, node.filename, level, node.type);
   }
   private _getLevel = (node: FileFlatNode) => node.level;
   private _isExpandable = (node: FileFlatNode) => node.expandable;
   private _getChildren = (node: FileNode): Observable<FileNode[]> => observableOf(node.children);
   hasChild = (_: number, _nodeData: FileFlatNode) => _nodeData.expandable;
}

Ergebnis

Überprüfen Sie das Ergebnis.

Einzelheiten

• Als erstes haben wir einen Baum mit Mat-Tree und Mat-Tree-Node erstellt.
• Dann haben wir die Datenquelle in der ts-Datei erstellt und sie mit mat-tree gebunden.