Set default option in mat-select

Question

I have a simple select option form field in my Angular material project:

component.html

Answer 1

HTML

<mat-form-field>
<mat-select [(ngModel)]="modeSelect" placeholder="Mode">
  <mat-option *ngFor="let obj of Array"  [value]="obj.value">{{obj.value}}</mat-option>
</mat-select>

Now set your default value to

modeSelect

, where you are getting the values in Array variable.

Answer 2

It took me several hours to figure out this until the similarity of the datatypes between the array and that of the default value worked for me...

Answer 3

Working StackBlitz

No need to use ngModel or Forms

In your html:

 <mat-form-field>
  <mat-select [(value)]="selected" placeholder="Mode">
    <mat-option value="domain">Domain</mat-option>
    <mat-option value="exact">Exact</mat-option>
  </mat-select>
</mat-form-field>

and in your component just set your public property selected to the default:

selected = 'domain';

Answer 4

I was able to set the default value or whatever value using the following:

Template:
          <mat-form-field>
              <mat-label>Holiday Destination</mat-label>
              <mat-select [(ngModel)]="selectedCity" formControlName="cityHoliday">
                <mat-option [value]="nyc">New York</mat-option>
                <mat-option [value]="london">London</mat-option>
                <mat-option [value]="india">Delhi</mat-option>
                <mat-option [value]="Oslo">Oslo</mat-option>
              </mat-select>
          </mat-form-field>

Component:

export class WhateverComponent implements OnInit{

selectedCity: string;    

}

ngOnInit() {
    this.selectedCity = 'london';
} 

}

Answer 5

I would like to add to Narm's answer here and have added the same as a comment under her answer.

Basically the datatype of the value assigned to [(value)] should match the datatype of the [value] attribute used for the mat-options. Especially if some one populates the options using an *ngFor as below

<mat-form-field fxHide.gt-sm='true'>
        <mat-select [(value)]="heroes[0].id">
          <mat-option *ngFor="let hero of heroes" [value]="hero.id">{{ hero.name }}</mat-option>
        </mat-select>
</mat-form-field>

Notice that, if you change the [(value)]="heroes[0].id" to [(value)]="heroes[0].name" it won't work as the data types don't match.

These are my findings, please feel free to correct me if needed.