Mat-Select Limit Multiple Selection

Introduction

mat-select is a form control component in Angular Material library that is used to display a dropdown list of options. By default, users can select one option at a time from the list. However, you can configure the mat-select control to allow users to select multiple options at once using mat-select with the multiple attribute.

Limiting Multiple Selections

Sometimes, you may want to limit the number of options that a user can select from a mat-select with multiple selection. To achieve this, you can use the mat-select with mat-select-trigger and mat-option with [disabled] attribute.

Here's an example of how to implement this feature:

<mat-form-field>
  <mat-select multiple placeholder="Select your toppings">
    <mat-select-trigger>
      {{ selectedToppings.length }} selected
    </mat-select-trigger>
    <mat-option *ngFor="let topping of toppingList" [value]="topping" 
      [disabled]="selectedToppings.length === maxToppings && !selectedToppings.includes(topping)">
      {{ topping }}
    </mat-option>
  </mat-select>
</mat-form-field>

In the above code snippet, we have an array of toppings called toppingList. We are using the mat-select control with multiple selection enabled, and we have added a placeholder to the control.

We are also using the mat-select-trigger property to display the number of selected toppings.

To limit the number of selections a user can make, we are using the [disabled] attribute with a condition to disable the option if the user has already selected the maximum number of toppings. Here, maxToppings is a property defined in the component that sets the maximum number of toppings that can be selected.

Conclusion

In summary, you can use mat-select with multiple selection to allow users to choose multiple options from a dropdown list. You can also limit the number of options that the user can select by using the [disabled] attribute with a condition to disable options that have already reached the maximum selection limit.

Returned Markdown code snippet:

## Mat-Select Limit Multiple Selection

### Introduction

`mat-select` is a form control component in Angular Material library that is used to display a dropdown list of options. By default, users can select one option at a time from the list. However, you can configure the `mat-select` control to allow users to select multiple options at once using `mat-select` with the `multiple` attribute.

### Limiting Multiple Selections

Sometimes, you may want to limit the number of options that a user can select from a `mat-select` with multiple selection. To achieve this, you can use the `mat-select` with `mat-select-trigger` and `mat-option` with `[disabled]` attribute.

Here's an example of how to implement this feature:

```html
<mat-form-field>
  <mat-select multiple placeholder="Select your toppings">
    <mat-select-trigger>
      {{ selectedToppings.length }} selected
    </mat-select-trigger>
    <mat-option *ngFor="let topping of toppingList" [value]="topping" 
      [disabled]="selectedToppings.length === maxToppings && !selectedToppings.includes(topping)">
      {{ topping }}
    </mat-option>
  </mat-select>
</mat-form-field>

In the above code snippet, we have an array of toppings called toppingList. We are using the mat-select control with multiple selection enabled, and we have added a placeholder to the control.

We are also using the mat-select-trigger property to display the number of selected toppings.

To limit the number of selections a user can make, we are using the [disabled] attribute with a condition to disable the option if the user has already selected the maximum number of toppings. Here, maxToppings is a property defined in the component that sets the maximum number of toppings that can be selected.

Conclusion

In summary, you can use mat-select with multiple selection to allow users to choose multiple options from a dropdown list. You can also limit the number of options that the user can select by using the [disabled] attribute with a condition to disable options that have already reached the maximum selection limit.