Pagination controls for mat-tab-group do not appear when used with the mat-sidenav

[epaitz]

I am trying to use the mat-sidenav with the mat-tab-group and there appears to be an issue with the pagination controls for the mat-tab-group. The test app will create 3 default tabs. If you add enough tabs so that there is just enough space to show the tabs without the tab pagination controls being displayed (based on your screen width), then open the sidenav by clicking the Toggle Sidenav button, the pagination controls do not appear in the tab control. Clicking the Add Tab button to add one more tab will force the tab control to reevaluate the horizontal space and then display the pagination controls for the tab control.

It appears that that the tab control is not aware that the horizontal space has decreased, because the sidenav is open, and does not show the pagination controls. The opposite is also true that if the pagination controls are displayed when the sidenav is open, when the sidenav is closed and there is enough horizontal space that the tab control no longer needs the pagination controls they do not disappear.

The desired behavior would be that the tab control will display or not display its pagination controls when necessary as the sidenav is open and closed.

  <mat-sidenav-container fxFill>
    <mat-sidenav #sidenav mode="side">
      <div style="height: 100%; width: 300px; background-color: lightblue;">
        <p>Sidenav</p>
      </div>
    </mat-sidenav>
    <mat-sidenav-content>
      <div fxLayout="column" fxFill>
        <div fxFlex="0 1 0%" fxLayoutGap="5px" style="padding: 5px">
          <button mat-stroked-button (click)="sidenav.toggle()">Toggle Sidenav</button>
          <button mat-stroked-button (click)="addTab()">Add Tab</button>
        </div>
        <div fxFlex="1 1 0%">
          <mat-tab-group>
            <mat-tab *ngFor="let tab of tabs" label="{{tab.label}}">
              <span>Tab content for {{tab.label}}</span>
            </mat-tab>
          </mat-tab-group>
        </div>
      </div>
    </mat-sidenav-content>
  </mat-sidenav-container>

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

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  tabs: any[] = [{label: "tab1"}, {label: "tab2"}, {label: "tab3"}]

  addTab() {
    this.tabs.push({label: "tab" + (this.tabs.length + 1)})
  }
}

[Splaktar]

Please submit Angular Material and CDK questions here and issues here. This repo is for AngularJS Material.

I have transferred this issue to the correct repository for you.

[jelbourn]

@epaitz can you share a stackblitz with this setup?

[epaitz]

@jelbourn

It might take a bit of playing around with it, and reloading between attempts, but here is the StackBlitz.
https://angular-material-mat-tab-with-sidenav.stackblitz.io

Here are the two scenarios as best I can describe them.

1. Have enough tabs so that the width does not need to show the pagination controls, with the sidenav closed but will need them when the sidenav is open, and then open the sidenav. The tabs will run off the screen and the pagination controls will not show unless another tab is added by clicking the Add Tab button.
2. Open the sidenav so that the pagination controls are visible (this should require clicking Add Tab once after the sidenav is open). Now close the sidenav so that there is enough space to show the tabs without the pagination controls…but they do not disappear. If there is still enough space to add one more tab, and not need the pagination controls, then click Add Tab and the pagination controls will disappear.

[andrewseguin]

This can be fixed if we expose the updatePagination method through the tab group. Then it can be called after the sidenav state changes, which already has events that output. Should be a trivial thing to add to the public API

[jelbourn]

@andrewseguin seems strange that that would be something the user would have to do at the application level.