Access MatDrawer using ViewChild is throwing error in Angular 8

Question

I'm trying to set the behavior of MatSideNav through component file using a property of type MatDrawer in Angular version 8

TypeScript Code:

// Declaration
@ViewChild('drawer', { static: false }) public drawer: MatDrawer;

// Toggle the Side Nav bar
showSideNav(): void {
    this.drawer.toggle();
}

HTML Code:

<mat-drawer-container>
      <mat-drawer #drawer>
        <div>Side nav bar content</div>
      </mat-drawer>
      <div>Main content</div>
</mat-drawer-container>

Console Error:

ERROR TypeError: "this.drawer is undefined"

Kindly assist me how to access the MatDrawer element using @ViewChild

Answer 1

I was able to resolve similar issue by passing the mat-drawer / sidenav id in the child component using @Input decorator, so in case of OP's problem statement something like this might work.

// Declaration
@Input drawerHandler: MatDrawer;

// Toggle the Side Nav bar
showSideNav(): void {
    this.drawerHandler.toggle();
}

And in template pass this input id value using a property binding

<mat-drawer-container>
      <mat-drawer #drawer [drawerHandler]="drawer">
        <div>Side nav bar content</div>
      </mat-drawer>
      <div>Main content</div>
</mat-drawer-container>

Answer 2

Change declaration from

@ViewChild('drawer', { static: false }) public drawer: MatDrawer;

to

@ViewChild('drawer', { static: true }) public drawer!: MatDrawer;

Answer 3

In my case, the problem was because I had not imported MatSidenavModule in my Angular module. I could still refer to MatDrawer without error because I had Material installed, but it was not in the module import list.