angular - material2数据表的使用方法

Question

我正在尝试实现 Material2 data table .但是我无法理解如何以正确的方式使用它。

import {Component, ElementRef, ViewChild} from '@angular/core';
import {DataSource} from '@angular/cdk';
import {BehaviorSubject} from 'rxjs/BehaviorSubject';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/startWith';
import 'rxjs/add/observable/merge';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/debounceTime';
import 'rxjs/add/operator/distinctUntilChanged';
import 'rxjs/add/observable/fromEvent';

@Component({
  selector: 'table-filtering-example',
  styleUrls: ['table-filtering-example.css'],
  templateUrl: 'table-filtering-example.html',
})
export class TableFilteringExample {
  displayedColumns = ['userId', 'userName', 'progress', 'color'];
  exampleDatabase = new ExampleDatabase();
  dataSource: ExampleDataSource | null;

  @ViewChild('filter') filter: ElementRef;

  ngOnInit() {
    this.dataSource = new ExampleDataSource(this.exampleDatabase);
    Observable.fromEvent(this.filter.nativeElement, 'keyup')
        .debounceTime(150)
        .distinctUntilChanged()
        .subscribe(() => {
          if (!this.dataSource) { return; }
          this.dataSource.filter = this.filter.nativeElement.value;
        });
  }
}

/** Constants used to fill up our data base. */
const COLORS = ['maroon', 'red', 'orange', 'yellow', 'olive', 'green', 'purple',
  'fuchsia', 'lime', 'teal', 'aqua', 'blue', 'navy', 'black', 'gray'];
const NAMES = ['Maia', 'Asher', 'Olivia', 'Atticus', 'Amelia', 'Jack',
  'Charlotte', 'Theodore', 'Isla', 'Oliver', 'Isabella', 'Jasper',
  'Cora', 'Levi', 'Violet', 'Arthur', 'Mia', 'Thomas', 'Elizabeth'];

export interface UserData {
  id: string;
  name: string;
  progress: string;
  color: string;
}

/** An example database that the data source uses to retrieve data for the table. */
export class ExampleDatabase {
  /** Stream that emits whenever the data has been modified. */
  dataChange: BehaviorSubject<UserData[]> = new BehaviorSubject<UserData[]>([]);
  get data(): UserData[] { return this.dataChange.value; }

  constructor() {
    // Fill up the database with 100 users.
    for (let i = 0; i < 100; i++) { this.addUser(); }
  }

  /** Adds a new user to the database. */
  addUser() {
    const copiedData = this.data.slice();
    copiedData.push(this.createNewUser());
    this.dataChange.next(copiedData);
  }

  /** Builds and returns a new User. */
  private createNewUser() {
    const name =
        NAMES[Math.round(Math.random() * (NAMES.length - 1))] + ' ' +
        NAMES[Math.round(Math.random() * (NAMES.length - 1))].charAt(0) + '.';

    return {
      id: (this.data.length + 1).toString(),
      name: name,
      progress: Math.round(Math.random() * 100).toString(),
      color: COLORS[Math.round(Math.random() * (COLORS.length - 1))]
    };
  }
}

/**
 * Data source to provide what data should be rendered in the table. Note that the data source
 * can retrieve its data in any way. In this case, the data source is provided a reference
 * to a common data base, ExampleDatabase. It is not the data source's responsibility to manage
 * the underlying data. Instead, it only needs to take the data and send the table exactly what
 * should be rendered.
 */
export class ExampleDataSource extends DataSource<any> {
  _filterChange = new BehaviorSubject('');
  get filter(): string { return this._filterChange.value; }
  set filter(filter: string) { this._filterChange.next(filter); }

  constructor(private _exampleDatabase: ExampleDatabase) {
    super();
  }

  /** Connect function called by the table to retrieve one stream containing the data to render. */
  connect(): Observable<UserData[]> {
    const displayDataChanges = [
      this._exampleDatabase.dataChange,
      this._filterChange,
    ];

    return Observable.merge(...displayDataChanges).map(() => {
      return this._exampleDatabase.data.slice().filter((item: UserData) => {
        let searchStr = (item.name + item.color).toLowerCase();
        return searchStr.indexOf(this.filter.toLowerCase()) != -1;
      });
    });
  }

  disconnect() {}
}

上面是让我很迷惑的datatable的代码。甚至他们的文档也很差。谁能解释一下上面代码的流程是什么？

如果您觉得问题太基础而无法提出，请忽略？

Answer 1

示例中的代码是通用表的定义，使用了 material2 规范中的新 cdk 组件。你必须记住 md-table 是 cdk-table 的可视化实现，所以你需要声明一个 cdk，其模型与 md-model 兼容HTML。

例如:

我使用以下实现声明了一个cdk-table:

1. 首先是依赖:

Material2 中的新 CDK 组件，使用:

import { DataSource } from '@angular/cdk';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/startWith';
import 'rxjs/add/observable/merge';
import 'rxjs/add/operator/map';

1. TS 中 HTML 结构的定义:

我定义了一个 displayedColumns 数组，项目是我的 HTML 表中的列，按顺序:

displayedColumns = ['userId', 'userName', 'progress'];

ExampleDatabase 类型的数据库(具有特定手动定义的对象):

exampleDatabase = new ExampleDatabase();

最后，我声明了一个dataSource，这是我数据的来源。是手动定义或数据为空的对象。

dataSource: ExampleDataSource | null;

在 ngOnInit() 方法中，我简单地声明我的 dataSource 是一个新的 ExampleDataSource ，参数是我的 exampleDataBase.

好的，现在开始实现其余的代码:

首先，为DataBase 声明一个接口(interface)。这对于保持数据的一致性非常重要，数据库必须遵守定义的方案。在这个例子中，数据库有三列:id、name 和 progress:

export interface UserData {
  id: number;
  name: string;
  progress: string;
}

下一步是使用我的DataBase 中的数据定义创建一个类(对象)ExampleDatabase。您可以创建连接到实际数据库(PostgreSQL、MongoDB)的服务，获取实际数据并使用另一种方法为 cdk-datatable 创建对象，但在本示例中，我们使用的是在运行时模拟的内存数据库。

export class ExampleDatabase {
  /** Stream that emits whenever the data has been modified. */
  dataChange: BehaviorSubject<UserData[]> = new BehaviorSubject<UserData[]>([]);
  get data(): UserData[] { return this.dataChange.value; }

  constructor() {
    // Fill up the database with 100 users.
    for (let i = 0; i < 100; i++) { this.addUser(); }
  }

  /** Adds a new user to the database. */
  addUser() {
    const copiedData = this.data.slice();
    copiedData.push(this.createNewUser());
    this.dataChange.next(copiedData);
  }

  /** Builds and returns a new User. */
  private createNewUser() {

    return {
      id: 1,
      name: 'example',
      progress: Math.round(Math.random() * 100).toString()
    };
  }
}

很好，最后我用我的 DataSource 定义创建了第二个类。

export class ExampleDataSource extends DataSource<any> {
  constructor(private _exampleDatabase: ExampleDatabase) {
    super();
  }

  /** Connect function called by the table to retrieve one stream containing the data to render. */
  connect(): Observable<UserData[]> {
    return this._exampleDatabase.dataChange;
  }

  disconnect() { }
}

此方法确保数据格式正确，并释放与DataBase(在内存中)的“连接”以获取其中的数据。

最后，在HTML中使用md-table组件或cdk-table组件。 md-table组件使用material design风格，cdk-table使用generic风格..

md 表:

<div class="example-container mat-elevation-z8">
  <md-table #table [dataSource]="dataSource">

    <!-- ID Column -->
    <ng-container cdkColumnDef="userId">
      <md-header-cell *cdkHeaderCellDef> ID </md-header-cell>
      <md-cell *cdkCellDef="let row"> {{row.id}} </md-cell>
    </ng-container>

    <!-- Progress Column -->
    <ng-container cdkColumnDef="progress">
      <md-header-cell *cdkHeaderCellDef> Progress </md-header-cell>
      <md-cell *cdkCellDef="let row"> {{row.progress}}% </md-cell>
    </ng-container>

    <!-- Name Column -->
    <ng-container cdkColumnDef="userName">
      <md-header-cell *cdkHeaderCellDef> Name </md-header-cell>
      <md-cell *cdkCellDef="let row"> {{row.name}} </md-cell>
    </ng-container>

    <md-header-row *cdkHeaderRowDef="displayedColumns"></md-header-row>
    <md-row *cdkRowDef="let row; columns: displayedColumns;"></md-row>
  </md-table>
</div>

cdk 表:

<div class="example-container mat-elevation-z8">
  <cdk-table #table [dataSource]="dataSource" class="example-table">

    <!-- ID Column -->
    <ng-container cdkColumnDef="userId">
      <cdk-header-cell *cdkHeaderCellDef class="example-header-cell"> ID </cdk-header-cell>
      <cdk-cell *cdkCellDef="let row" class="example-cell"> {{row.id}} </cdk-cell>
    </ng-container>

    <!-- Progress Column -->
    <ng-container cdkColumnDef="progress">
      <cdk-header-cell *cdkHeaderCellDef class="example-header-cell"> Progress </cdk-header-cell>
      <cdk-cell *cdkCellDef="let row" class="example-cell"> {{row.progress}}% </cdk-cell>
    </ng-container>

    <!-- Name Column -->
    <ng-container cdkColumnDef="userName">
      <cdk-header-cell *cdkHeaderCellDef class="example-header-cell"> Name </cdk-header-cell>
      <cdk-cell *cdkCellDef="let row" class="example-cell"> {{row.name}} </cdk-cell>
    </ng-container>

    <cdk-header-row *cdkHeaderRowDef="displayedColumns" class="example-header-row"></cdk-header-row>
    <cdk-row *cdkRowDef="let row; columns: displayedColumns;" class="example-row"></cdk-row>
  </cdk-table>
</div>

其余的实现、搜索、菜单、复选框等，由您负责实现处理信息的逻辑。

使用有关 cdk-table 的文档了解更多详细信息:

https://material.angular.io/guide/cdk-table

结果:

Do me saber and achievement，我理解我的解释，我为我的英语道歉。我在学习。