Angular - Array as Select Option Values

Question

I have this TypeScript:

public sendAlertDays: Array<any> = [
    { value: [0, 1, 2, 3, 4, 5, 6], text: "all days" },
    { value: [0, 1, 2, 3, 4], text: "monday-friday" },
    { value: [5, 6], text: "saturday-sunday" },
    { value: [0], text: "monday" },
    { value: [1], text: "tuesday" },
    { value: [2], text: "wednesday" },
    { value: [3], text: "thursday" },
    { value: [4], text: "friday" },
    { value: [5], text: "saturday" },
    { value: [6], text: "sunday" }
];

sendAlertDay: number[] = [0];

My Angular template do not pre-select 'monday' yet I have initialized well sendAlertDay: number[] = [0]

<mat-select [(value)]="sendAlertDay" class="mat-primary">
    <mat-option *ngFor="let day of sendAlertDays" [value]="day.value">
        {{day.text}}
    </mat-option>
</mat-select>

Can you maybe share a stackblitz?

MoxxiManagarm
– MoxxiManagarm

2019-11-26 14:50:18 +00:00
Commented Nov 26, 2019 at 14:50 — MoxxiManagarm
– MoxxiManagarm, Commented Nov 26, 2019 at 14:50

C.OG · Accepted Answer · 2019-11-26 15:29:11Z

You will need to use the compareWith property of the mat-select.

@Input() compareWith: (o1: any, o2: any) => boolean

Function to compare the option values with the selected values. The first argument is a value from an option. The second is a value from the selection. A boolean should be returned.

Your component:

public sendAlertDays: Array<any> = [
    { value: [0, 1, 2, 3, 4, 5, 6], text: "all days" },
    { value: [0, 1, 2, 3, 4], text: "monday-friday" },
    { value: [5, 6], text: "saturday-sunday" },
    { value: [0], text: "monday" },
    { value: [1], text: "tuesday" },
    { value: [2], text: "wednesday" },
    { value: [3], text: "thursday" },
    { value: [4], text: "friday" },
    { value: [5], text: "saturday" },
    { value: [6], text: "sunday" }
];

sendAlertDay: number[] = [0];

compareFN(optionValue: number[], selectionValue: number[]) {
    // compare two arrays
    return (
        optionValue.length === selectionValue.length &&
        optionValue.every((value, index) => value === selectionValue[index])
    );
}

Your template:

 <mat-select [(value)]="sendAlertDay" [compareWith]="compareFN" class="mat-primary">
     <mat-option *ngFor="let day of sendAlertDays" [value]="day.value">
         {{day.text}}
     </mat-option>
 </mat-select>

Demo on stackblitz

KLTR · Accepted Answer · 2019-11-26 15:06:10Z

You can not set the selected value to be an array.

in order for this to work you need to set the value to be string instead of number[]

this for example would work :

      public sendAlertDays: Array<any> = [
      { value: 'all', text: 'all days' },
      { value: 'monday-to-friday', text: 'monday-friday' },
      { value: 'saturday-sunday', text: 'saturday-sunday' },
      { value: 'monday', text: 'monday' },     
      { value: 'tuesday', text: 'tuesday' },
      { value: 'wednesday', text: 'wednesday' },
      { value: 'thursday', text: 'thursday' },
      { value: 'friday', text: 'friday' },
      { value: 'saturday', text: 'saturday' },
      { value: 'sunday', text: 'sunday' }];

      sendAlertDay: string = 'monday';

here's a stackblitz: https://stackblitz.com/edit/angular-2wzrmk-se36mv

an alternative would be to set the value to number, this would work as well

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