NullInjectorError: No provider for MatDialogRef

Question

I can't inject MatDialogRef as it described in documentation: https://material.angular.io/components/dialog/overview

When i'm trying to do it i'v got error:

ERROR Error: StaticInjectorError[MatDialogRef]: StaticInjectorError[MatDialogRef]: NullInjectorError: No provider for MatDialogRef!

app.module.ts

home.component.ts

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

import { MatDialog } from '@angular/material';
import { RegistrationComponent } from '../account/components/registration.component';

@Component({
    moduleId: module.id.replace('compiled', 'app'),
    templateUrl: 'home.component.html'
})
export class HomeComponent
{
    constructor(private modalService: MatDialog) {}

    public openModal() : void
    {
        let dialog = this.modalService.open(RegistrationComponent, {});
    }
}

registration.component.ts

import { Component } from '@angular/core';
import { Router } from '@angular/router';
import { MatDialogRef } from '@angular/material/dialog';

import { User } from '../../../models/domain/User';
import { ApiUserService } from '../../api/entity-services/user.service';
import { AuthService } from '../../auth/auth.service';
import { AccountService } from '../services/account.service'

@Component({
	selector: 'registration-component',
	templateUrl: 'app/modules/account/templates/registration.component.html'
})
export class RegistrationComponent
{
	public user :User = new User();

	public errorMessage :string;

	public isLoading :boolean;

	constructor
	(
		private userService :ApiUserService,
		private authService :AuthService,
		private accountService :AccountService,
		private router :Router,
		public dialogRef :MatDialogRef<RegistrationComponent>
	)
	{
		this.isLoading = false;
	}

	public onSubmit(e) :void
	{
		e.preventDefault();
		this.isLoading = true;

		this.userService
			.Create(this.user)
			.subscribe(
				user =>
				{
					this.user.id = user.id;
					this.user.login = user.login;


					this.authService
						.Login(this.user)
						.subscribe(
							token =>
							{
								this.accountService.Load()
									.subscribe(
										account =>
										{
											this.user = account;
											this.isLoading = false;
											this.dialogRef.close();

											let redirectRoute = account.activeScopeId
												? `/scope/${account.activeScopeId}`
												: '/scope-list/';

											this.router.navigate([redirectRoute]);
										},
										error => this.errorMessage = <any>error
									);
							},
							error => this.errorMessage = <any>error
						);
				},
				error => this.errorMessage = <any>error
			);
	}
}

Answer 1

I had this error when adding dialogs to a service to be shared in many components. Just to clarify, the error wasnt present in the application before moving dialogs to the service. The solution was to include a custom provider MatDialogRef in the main module

  import {DialogService} from './services/dialog.service';
  import {MatDialogModule, MatDialogRef} from '@angular/material/dialog';
  ...
  imports: [
    ...
    MatDialogModule
  ],
  providers: [
     {
       provide: MatDialogRef,
       useValue: {}
     },
     DialogService
  ],
  ...

With this provider the service worked as a singleton with my dialogs to be shared and the provider error was gone.