Displaying Selected Option Names with Angular 7 Mat-Select

In Angular 7, displaying the selected option name inside the <mat-select> trigger is a common requirement for enhancing user interfaces. This feature ensures that users can easily see their current selection, improving the overall usability and accessibility of the application. By clearly showing the selected option, users can quickly verify their choices, reducing confusion and enhancing the user experience.

Setting Up Angular 7 Project

Here are the steps to set up an Angular 7 project and configure it to use Angular Material with mat-select:

1. Install Angular CLI:

   npm install -g @angular/cli
   

2. Create a new Angular project:

   ng new my-angular-project
   cd my-angular-project
   

3. Add Angular Material:

   ng add @angular/material
   

   • Choose a prebuilt theme.
   • Enable global typography styles.
   • Enable browser animations.

4. Import BrowserAnimationsModule:
   In src/app/app.module.ts, import BrowserAnimationsModule:

   import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
   
   @NgModule({
     ...
     imports: [
       BrowserAnimationsModule,
       ...
     ],
     ...
   })
   export class AppModule { }
   

5. Import MatSelectModule:
   In src/app/app.module.ts, import MatSelectModule:

   import { MatSelectModule } from '@angular/material/select';
   
   @NgModule({
     ...
     imports: [
       MatSelectModule,
       ...
     ],
     ...
   })
   export class AppModule { }
   

6. Add Angular Material theme:
   In src/styles.css, add:

   @import "~@angular/material/prebuilt-themes/indigo-pink.css";
   

7. Use mat-select in a component:
   In your component HTML file (e.g., src/app/app.component.html):

   <mat-form-field>
     <mat-label>Favorite food</mat-label>
     <mat-select>
       <mat-option *ngFor="let food of foods" [value]="food.value">
         {{food.viewValue}}
       </mat-option>
     </mat-select>
   </mat-form-field>
   

   In your component TypeScript file (e.g., src/app/app.component.ts):

   export class AppComponent {
     foods: any[] = [
       {value: 'steak-0', viewValue: 'Steak'},
       {value: 'pizza-1', viewValue: 'Pizza'},
       {value: 'tacos-2', viewValue: 'Tacos'}
     ];
   }
   

That’s it! Your Angular 7 project is now set up with Angular Material and configured to use mat-select.

Creating Mat-Select Component

Here’s how you can create a mat-select component in Angular 7 with some basic options:

1. Install Angular Material:

   ng add @angular/material
   

2. Import MatSelectModule in your app module:

   import { MatSelectModule } from '@angular/material/select';
   import { MatFormFieldModule } from '@angular/material/form-field';
   
   @NgModule({
     imports: [
       MatSelectModule,
       MatFormFieldModule,
       // other imports
     ],
   })
   export class AppModule { }
   

3. Add MatSelect in your component template:

   <mat-form-field>
     <mat-label>Favorite food</mat-label>
     <mat-select [(value)]="selectedFood">
       <mat-option *ngFor="let food of foods" [value]="food.value">
         {{ food.viewValue }}
       </mat-option>
     </mat-select>
   </mat-form-field>
   

4. Define the options in your component class:

   import { Component } from '@angular/core';
   
   @Component({
     selector: 'app-select-example',
     templateUrl: './select-example.component.html',
     styleUrls: ['./select-example.component.css']
   })
   export class SelectExampleComponent {
     selectedFood: string;
     foods: any[] = [
       { value: 'steak-0', viewValue: 'Steak' },
       { value: 'pizza-1', viewValue: 'Pizza' },
       { value: 'tacos-2', viewValue: 'Tacos' }
     ];
   }
   

This setup will create a basic mat-select dropdown with options for “Steak,” “Pizza,” and “Tacos.”

Displaying Selected Option Name

Here’s how you can show the selected option name inside the mat-select trigger tags using Angular 7:

Step-by-Step Process

1. Install Angular Material: If you haven’t already, install Angular Material in your project.

   ng add @angular/material
   

2. Import Angular Material Modules: Import the necessary Angular Material modules in your app.module.ts.

   import { MatSelectModule } from '@angular/material/select';
   import { MatFormFieldModule } from '@angular/material/form-field';
   import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
   
   @NgModule({
     declarations: [AppComponent],
     imports: [
       BrowserModule,
       BrowserAnimationsModule,
       MatSelectModule,
       MatFormFieldModule
     ],
     providers: [],
     bootstrap: [AppComponent]
   })
   export class AppModule { }
   

3. Create the Component: Create a component where you will use the mat-select.

   ng generate component custom-select
   

4. HTML Template: Update the HTML template of your component to include the mat-select with a custom trigger.

   <mat-form-field appearance="fill">
     <mat-label>Select an option</mat-label>
     <mat-select [(value)]="selectedOption">
       <mat-select-trigger>
         {{ selectedOption ? selectedOption : 'Select an option' }}
       </mat-select-trigger>
       <mat-option *ngFor="let option of options" [value]="option">
         {{ option }}
       </mat-option>
     </mat-select>
   </mat-form-field>
   

5. Component Class: Define the options and the selected option in your component class.

   import { Component } from '@angular/core';
   
   @Component({
     selector: 'app-custom-select',
     templateUrl: './custom-select.component.html',
     styleUrls: ['./custom-select.component.css']
   })
   export class CustomSelectComponent {
     options: string[] = ['Option 1', 'Option 2', 'Option 3'];
     selectedOption: string;
   }
   

Key Concepts

• mat-select: This is the Angular Material component for creating a dropdown select box.
• mat-select-trigger: This directive allows you to customize the display of the selected value inside the mat-select trigger.
• [(value)] Binding: This two-way data binding ensures that the selected option is updated in the component class and reflected in the template.

By following these steps, you can display the selected option name inside the mat-select trigger tags in Angular 7.

Handling Edge Cases

Here are some common edge cases and how to handle them when showing the selected option name inside the mat-select trigger tags in Angular 7:

1. Long Option Names:

   • Issue: Long option names can overflow or be truncated.
   • Solution: Use CSS to handle text overflow. For example:

     .mat-select-trigger {
       white-space: nowrap;
       overflow: hidden;
       text-overflow: ellipsis;
     }
     

2. No Option Selected:

   • Issue: The trigger might display an empty state or placeholder.
   • Solution: Set a default placeholder or handle the empty state in the template:

     <mat-select placeholder="Select an option" [(value)]="selectedValue">
       <mat-option *ngFor="let option of options" [value]="option">{{ option }}</mat-option>
     </mat-select>
     

3. Multiple Selections:

   • Issue: Displaying multiple selected options in a single line.
   • Solution: Customize the trigger to show a summary or count of selected options:

     <mat-select multiple [(value)]="selectedValues">
       <mat-select-trigger>
         {{selectedValues.length}} options selected
       </mat-select-trigger>
       <mat-option *ngFor="let option of options" [value]="option">{{ option }}</mat-option>
     </mat-select>
     

4. Dynamic Option Changes:

   • Issue: Options change dynamically, and the trigger might not update correctly.
   • Solution: Ensure the component detects changes by using Angular’s change detection:

     import { ChangeDetectorRef } from '@angular/core';
     
     constructor(private cdr: ChangeDetectorRef) {}
     
     updateOptions(newOptions: any[]) {
       this.options = newOptions;
       this.cdr.detectChanges();
     }
     

5. Custom Display for Selected Option:

   • Issue: Need to display a custom template for the selected option.
   • Solution: Use the mat-select-trigger directive to customize the display:

     <mat-select [(value)]="selectedValue">
       <mat-select-trigger>
         <span *ngIf="selectedValue">{{ selectedValue.name }}</span>
       </mat-select-trigger>
       <mat-option *ngFor="let option of options" [value]="option">{{ option.name }}</mat-option>
     </mat-select>
     

These solutions should help you handle common edge cases effectively when working with mat-select in Angular 7.

To Display Selected Option Name Inside mat-select Trigger Tags in Angular 7

You can use the following approach:

• Use the [value] property to bind the selected value to the mat-select.
• Inside the mat-select-trigger, use a span element with an ngIf directive to conditionally display the selected option name.
• Bind the selectedValue property to the span element using interpolation ({{ }}) to display its name.

Example Code Snippet:

<mat-select [(value)]="selectedValue">
  <mat-select-trigger>
    <span *ngIf="selectedValue">{{ selectedValue.name }}</span>
  </mat-select-trigger>
  <mat-option *ngFor="let option of options" [value]="option">{{ option.name }}</mat-option>
</mat-select>

This approach allows you to display the selected option name inside the mat-select trigger tags, providing a more user-friendly experience.

Benefits:

• Improved user experience: By displaying the selected option name, users can easily see what they have chosen.
• Enhanced accessibility: Screen readers and other assistive technologies can now read out the selected option name, making it easier for users with disabilities to navigate the application.
• Consistency: This approach maintains consistency across different components and applications, ensuring a cohesive user experience.

By implementing this feature, you can enhance the overall usability and accessibility of your Angular 7 application.