AngularJS is a JavaScript-based framework. It can be used by adding it to an HTML page using a <script> tag. AngularJS helps in extending the HTML attributes with the help of directives and binding of data to the HTML with expressions. An Angular service is a broad category that consists of any value, function, or feature that an application needs. A service is a class with a narrow and well-defined purpose. In this article, we will see how to bind a select element to an object in AngularJS. The process of binding a select element to an object helps in associating the selected value with a property in our component class.
Steps to bind select element to object: The below steps will be followed for binding the select element to the object in Angular:
Step 1: Create a new Angular project and install the necessary dependencies
ng new my-app cd my-app
Step 2: Create a new Angular component
ng generate component my-component
This will create a new directory called “my-component” in your project’s “src/app” directory, along with the necessary files for an Angular component.
Step 3: Create an interface or class to define the structure of the options
export interface Option { value: string; displayText: string; }
Step 4: Define an array of options in your component
export class MyComponentComponent { options = [ { id: 1, name: 'Java' }, { id: 2, name: 'C++' }, { id: 3, name: 'Python' } ]; selectedOption: any; }
Step 5: Use the ngFor directive to generate the options in the select element
<select [(ngModel)]="selectedOption"> <option *ngFor="let option of options" [ngValue]="option"> {{option.name}} </option> </select>
Step 6: Use the selected option in your component
<p>You selected: {{ selectedOption | json }}</p>
We will understand the above concept with the help of suitable approaches & will understand its implementation through the illustration.
Approach 1: In this approach, we are using the ngValue directive to bind the entire object to the value attribute of the option element. This approach requires a compareWith function to be defined to properly compare the selected option with the options in the array.
Example 1: Below example demonstrates the binding of the select element to an object in angular.
- app.module.ts
import { NgModule } from '@angular/core' ;
import { BrowserModule } from '@angular/platform-browser' ;
import { FormsModule } from '@angular/forms' ;
import { AppComponent } from './app.component' ;
import { MyComponentComponent } from './my-component/my-component.component' ;
@NgModule({ declarations: [
AppComponent,
MyComponentComponent
],
imports: [
BrowserModule,
FormsModule
],
providers: [],
bootstrap: [AppComponent]
}) export class AppModule { } |
- my-component-component.html
< h2 style = "color: green" >
GeeksforGeeks
</ h2 >
< select [(ngModel)]="selectedOption">
< option * ngFor = "let option of options" [ngValue]="option">
{{ option.name }}
</ option >
</ select >
< p >
You selected: {{ selectedOption | json }}
</ p >
|
- my-component-component.ts
import { Component } from '@angular/core' ;
@Component({ selector: 'app-my-component' ,
templateUrl: './my-component.component.html' ,
styleUrls: [ './my-component.component.css' ]
}) export class MyComponentComponent { options = [
{ id: 1, name: 'Java' },
{ id: 2, name: 'C++' },
{ id: 3, name: 'Python' }
];
selectedOption: any;
} |
- app.component.html
< app-my-component ></ app-my-component >
|
Output:
Approach 2: In this approach, we are using the value attribute of the option element to bind the entire object to the selectedOption property. This approach does not require a compareWith function and is simpler to set up.
Example 2: This is another example that demonstrates the binding of the select element to an object in Angular.
- app.module.ts
import { NgModule } from '@angular/core' ;
import { BrowserModule } from '@angular/platform-browser' ;
import { FormsModule } from '@angular/forms' ;
import { AppComponent } from './app.component' ;
import { SelectObjectComponent } from './select-object/select-object.component' ;
@NgModule({ declarations: [
AppComponent,
SelectObjectComponent
],
imports: [
BrowserModule,
FormsModule
],
providers: [],
bootstrap: [AppComponent]
}) export class AppModule { } |
- select-object.component.html
< h2 >My Component</ h2 >
< select [(ngModel)]="selectedOptions">
< option * ngFor = "let option of options" [value]="option.name">
{{ option.name }}
</ option >
</ select >
< p >
Selected Option: {{ selectedOptions | json }}
</ p >
|
- select-object-component.ts
import { Component } from '@angular/core' ;
@Component({ selector: 'app-select-object' ,
templateUrl: './select-object.component.html' ,
styleUrls: [ './select-object.component.css' ]
}) export class SelectObjectComponent { options: any = [
{ id: 1, name: 'HTML' },
{ id: 2, name: 'CSS' },
{ id: 3, name: 'Javascript' },
{ id: 4, name: 'MongoDb' }
];
selectedOptions: any
} |
- app.component.html
< app-select-object ></ app-select-object >
|
Output: