如何刷新一个数据源(mat-table)

我正在使用一个垫子表列出用户选择的语言的内容。他们还可以使用对话框面板添加新的语言。在他们添加了一门语言并返回之后。我希望刷新数据源以显示他们所做的更改。

我通过从服务获取用户数据并在刷新方法中将其传递到数据源来初始化数据存储。

Language.component.ts

import { Component, OnInit } from '@angular/core';
import { LanguageModel, LANGUAGE_DATA } from '../../../../models/language.model';
import { LanguageAddComponent } from './language-add/language-add.component';
import { AuthService } from '../../../../services/auth.service';
import { LanguageDataSource } from './language-data-source';
import { LevelbarComponent } from '../../../../directives/levelbar/levelbar.component';
import { DataSource } from '@angular/cdk/collections';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/of';
import { MatSnackBar, MatDialog } from '@angular/material';

@Component({
  selector: 'app-language',
  templateUrl: './language.component.html',
  styleUrls: ['./language.component.scss']
})
export class LanguageComponent implements OnInit {

  displayedColumns = ['name', 'native', 'code', 'level'];
  teachDS: any;
  user: any;

  constructor(private authService: AuthService, private dialog: MatDialog) { }

  ngOnInit() {
    this.refresh();
  }

  add() {
    this.dialog.open(LanguageAddComponent, {
      data: { user: this.user },
    }).afterClosed().subscribe(result => {
      this.refresh();
    });
  }

  refresh() {
    this.authService.getAuthenticatedUser().subscribe((res) => {
      this.user = res;
      this.teachDS = new LanguageDataSource(this.user.profile.languages.teach);   
    });
  }
}

language-data-source.ts

import {MatPaginator, MatSort} from '@angular/material';
import {DataSource} from '@angular/cdk/collections';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/observable/merge';
import 'rxjs/add/operator/map';

export class LanguageDataSource extends DataSource<any> {

  constructor(private languages) {
    super();
  }

  connect(): Observable<any> {
    return Observable.of(this.languages);
  }

  disconnect() {
    // No-op
  }

}

因此，我尝试调用一个刷新方法，我从后端再次获得用户，然后重新初始化数据源。然而，这并没有起作用，没有发生任何变化。

当前回答

在refresh()方法中使用ChangeDetectorRef触发变更检测在接收到新数据后，在构造函数中注入ChangeDetectorRef，并像这样使用detectChanges:

import { Component, OnInit, ChangeDetectorRef } from '@angular/core';
import { LanguageModel, LANGUAGE_DATA } from '../../../../models/language.model';
import { LanguageAddComponent } from './language-add/language-add.component';
import { AuthService } from '../../../../services/auth.service';
import { LanguageDataSource } from './language-data-source';
import { LevelbarComponent } from '../../../../directives/levelbar/levelbar.component';
import { DataSource } from '@angular/cdk/collections';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/of';
import { MatSnackBar, MatDialog } from '@angular/material';

@Component({
  selector: 'app-language',
  templateUrl: './language.component.html',
  styleUrls: ['./language.component.scss']
})
export class LanguageComponent implements OnInit {
  displayedColumns = ['name', 'native', 'code', 'level'];
  teachDS: any;

  user: any;

  constructor(private authService: AuthService, private dialog: MatDialog,
              private changeDetectorRefs: ChangeDetectorRef) { }

  ngOnInit() {
    this.refresh();
  }

  add() {
    this.dialog.open(LanguageAddComponent, {
      data: { user: this.user },
    }).afterClosed().subscribe(result => {
      this.refresh();
    });
  }

  refresh() {
    this.authService.getAuthenticatedUser().subscribe((res) => {
      this.user = res;
      this.teachDS = new LanguageDataSource(this.user.profile.languages.teach);
      this.changeDetectorRefs.detectChanges();
    });
  }
}

2017-10-14 16:39:25

其他回答

this.dataSource = new MatTableDataSource<Element>(this.elements);

将这一行添加到添加或删除特定行的操作下面。

refresh() {
  this.authService.getAuthenticatedUser().subscribe((res) => {
    this.user = new MatTableDataSource<Element>(res);   
  });
}

2018-03-09 06:52:09

似乎您的refresh()函数正在适当地向teachDS数据源添加一个新实例。但是，表没有被更新，因为它没有被指示这样做。

你可以指示Angular使用ChangeDetectorRef服务监控数据源的变化，并在必要时更新表。

ChangeDetectorRef服务必须首先注入到你的组件中:

import { ChangeDetectorRef } from '@angular/core';

constructor(
            private authService: AuthService, 
            private dialog: MatDialog, 
            private changeDetectorRef: ChangeDetectorRef
) { }

然后，在refresh()函数中刷新数据源后，你可以指示Angular检查更改并通过changeDetectorRef上的detectChanges()方法更新表:

refresh() {
  this.authService.getAuthenticatedUser().subscribe((res) => {
    this.user = res;
    this.teachDS = new LanguageDataSource(this.user.profile.languages.teach);
    this.changeDetectorRef.detectChanges();  // <-- Tell Angular to check for changes
  });
}

因此，应该更新表以反映数据源的更改。

2023-01-08 08:01:47

我认为MatTableDataSource对象在某种程度上与你传递给MatTableDataSource构造函数的数据数组相关联。

例如:

dataTable: string[];
tableDS: MatTableDataSource<string>;

ngOnInit(){
   // here your pass dataTable to the dataSource
   this.tableDS = new MatTableDataSource(this.dataTable); 
}

所以，当你需要改变数据时;改变原始列表dataTable，然后通过调用tableDS上的_updatechangesub兵役()方法反映表上的变化。

例如:

this.dataTable.push('testing');
this.tableDS._updateChangeSubscription();

这就是我在Angular 6中的工作。

2018-11-06 07:45:29

在refresh()方法中使用ChangeDetectorRef触发变更检测在接收到新数据后，在构造函数中注入ChangeDetectorRef，并像这样使用detectChanges:

import { Component, OnInit, ChangeDetectorRef } from '@angular/core';
import { LanguageModel, LANGUAGE_DATA } from '../../../../models/language.model';
import { LanguageAddComponent } from './language-add/language-add.component';
import { AuthService } from '../../../../services/auth.service';
import { LanguageDataSource } from './language-data-source';
import { LevelbarComponent } from '../../../../directives/levelbar/levelbar.component';
import { DataSource } from '@angular/cdk/collections';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/observable/of';
import { MatSnackBar, MatDialog } from '@angular/material';

@Component({
  selector: 'app-language',
  templateUrl: './language.component.html',
  styleUrls: ['./language.component.scss']
})
export class LanguageComponent implements OnInit {
  displayedColumns = ['name', 'native', 'code', 'level'];
  teachDS: any;

  user: any;

  constructor(private authService: AuthService, private dialog: MatDialog,
              private changeDetectorRefs: ChangeDetectorRef) { }

  ngOnInit() {
    this.refresh();
  }

  add() {
    this.dialog.open(LanguageAddComponent, {
      data: { user: this.user },
    }).afterClosed().subscribe(result => {
      this.refresh();
    });
  }

  refresh() {
    this.authService.getAuthenticatedUser().subscribe((res) => {
      this.user = res;
      this.teachDS = new LanguageDataSource(this.user.profile.languages.teach);
      this.changeDetectorRefs.detectChanges();
    });
  }
}

2017-10-14 16:39:25

import { Subject } from 'rxjs/Subject';
import { Observable } from 'rxjs/Observable';

export class LanguageComponent implemnts OnInit {
  displayedColumns = ['name', 'native', 'code', 'leavel'];
  user: any;
  private update = new Subject<void>();
  update$ = this.update.asObservable();

  constructor(private authService: AuthService, private dialog: MatDialog) {}

   ngOnInit() {
     this.update$.subscribe(() => { this.refresh()});
   }

   setUpdate() {
     this.update.next();
   }

   add() {
     this.dialog.open(LanguageAddComponent, {
     data: { user: this.user },
   }).afterClosed().subscribe(result => {
     this.setUpdate();
   });
 }

 refresh() {
   this.authService.getAuthenticatedUser().subscribe((res) => {
     this.user = res;
     this.teachDS = new LanguageDataSource(this.user.profile.languages.teach);   
    });
  }
}

2018-04-23 15:17:43

如何刷新一个数据源(mat-table)

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