Ways to activate button only when an item is chosen from the dropdown menu

I'm working on an Angular 8 application that utilizes Angular Material. I have multiple dropdown lists with a button that triggers a function based on the selected values from the dropdowns.

Initially, when the page loads, the button is disabled. However, upon selecting a value from the dropdown list, the button becomes enabled. The issue arises when no value is selected from the dropdown list; the button remains enabled instead of being disabled.

My question is: How can I disable the button when no value is selected from the dropdown list?

This is the TypeScript code snippet:


buttonFilterDisabled: boolean;

selectedSearch: string;
selectedValue: string;

onChange3(event){
  this.buttonFilterDisabled = true;
}
<div class="search-select searchstatus" *ngIf="selectedSearch && hasStatusOptions(selectedSearch)">
        <mat-select
          placeholder="Status"
          name="option"
          [(ngModel)]="selectedValue"
          (filterparticipantByRegistration)="enableSubmit($event)"
          (ngModelChange)="onChange3($event)"
        >
          <mat-option value="">--Selecteer een status--</mat-option>
          <mat-option *ngFor="let option of getStatusOptions(selectedSearch)" [value]="option.apiStatus">
            {{ option.status }}
          </mat-option>
        </mat-select>
      </div>

And here's the button element:

  <button [disabled]="!buttonFilterDisabled" mat-raised-button color="accent" class="Button" (click)="searchFor()">
        Filter
      </button>

In addition to the dropdown lists, there are also radio items accompanied by a date field. Even when the date field is filled in, the button appears disabled. This behavior is incorrect as the button should be enabled when a date is entered.

The radio buttons section:

<div class="search-types">
      <mat-radio-group>
        <mat-radio-button
          *ngFor="let option of searchOptions"
          [value]="option"
          (change)="setSelectedSearchOptions(option.label)"
        >
          {{ option.label }}
        </mat-radio-button>
      </mat-radio-group>
    </div>

And the datepicker component:

 <div>
      <mat-form-field class="search-field-input md-datepicker-input-container">
        <input
          matInput
          readonly
          required
          [matDatepicker]="picker1"
          placeholder="start datum"
          [(ngModel)]="startDate"
          (ngModelChange)="onChange3($event)"
        />
        <mat-datepicker-toggle matSuffix [for]="picker1" ></mat-datepicker-toggle>
        <mat-datepicker #picker1></mat-datepicker>
      </mat-form-field>
    </div>

Furthermore, I have created a function to handle changes in the selected search options:

 setSelectedSearchOptions(optionLabel: string) {
    // Function implementation 
}

When the 'Inlog' radio button option is selected, the button should be enabled if a date is filled in. However, it currently remains disabled even when a date is provided.

Answer №1

To resolve the problem, simply include [disabled]="!selectedValue"

Answer №2

Ensure to validate the value within the onChange3 function. Here's an example of how you can implement this:

onChange3(event){
  this.buttonFilterDisabled = (this.selectedValue !== '');
}

It is recommended to avoid using numbers in method names, stick to standard naming conventions.

Alternatively, you can achieve this directly like so:

[disabled]="!selectedValue"

Answer №3

To simplify your code, consider removing the change event and the variable buttonFilterDisabled

<div class="search-select searchstatus" *ngIf="selectedSearch && hasStatusOptions(selectedSearch)">
        <mat-select
          placeholder="Status"
          name="option"
          [(ngModel)]="selectedValue"
          (filterparticipantByRegistration)="enableSubmit($event)"
        >
          <mat-option value="">--Select a status--</mat-option>
          <mat-option *ngFor="let option of getStatusOptions(selectedSearch)" [value]="option.apiStatus">
            {{ option.status }}
          </mat-option>
        </mat-select>
</div>

Your button can now be a simple:

 <button [disabled]="!selectedValue" mat-raised-button color="accent" class="Button" (click)="searchFor()">
        Filter
      </button>

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