We have a reactive form control:

control:FormControl = new FormControl('steak-0')

And we want to bind it to our mat-select element such that we can:

Receive reactive notifications from control.valueChanges
Have the mat-select default value be steak-0

Approach

Within the app.module.ts we have imported both FormsModule and ReactiveFormsModule.

In the below app.component.ts component we have created an control:FormControl instance and initialized the value to steak-0.

import { Component, VERSION } from "@angular/core";
import { FormControl } from "@angular/forms";
interface Food {
    value: string;
    viewValue: string;
}
@Component({
    selector: "my-app",
    templateUrl: "./app.component.html",
    styleUrls: ["./app.component.css"]
})
export class AppComponent {
    control = new FormControl("steak-0");
    foods: Food[] = [
        { value: "steak-0", viewValue: "Steak" },
        { value: "pizza-1", viewValue: "Pizza" },
        { value: "tacos-2", viewValue: "Tacos" }
    ];
constructor() {
    this.control.valueChanges.subscribe(s => {
        console.log(`The selected value is ${s}`);
    });
    }
}

In the app.component.html we have two declarations of mat-select. The first mat-select declaration does not bind to control.

As can be seen the mat-select uses the <mat-label>Favorite food</mat-label> as the place holder instruction telling the user to select a food in this case.

In the second case, where we have bound the mat-select to the form control like this <mat-select [formControl]="control">, the mat-select value is initialized to steak-0.

We subscribe to the form control within the app.component.ts constructor.

this.control.valueChanges.subscribe(s => {
    console.log(`The selected value is ${s}`);
});

Whenever we change the selection, the subscription logs the selected value.

Binding Angular Material Select to a Reactive Form Control | Task

Scenario

Approach

Demo