Angular - HTTP GET Request Examples
Below is a quick set of examples to show how to send HTTP GET requests from Angular to a backend API.
Other HTTP examples available:
- Angular: POST, PUT, DELETE
- React + Fetch: GET, POST, PUT, DELETE
- React + Axios: GET, POST, PUT, DELETE
- Vue + Fetch: GET, POST, PUT, DELETE
- Vue + Axios: GET, POST
- Blazor WebAssembly: GET, POST
- Axios: GET, POST, PUT, DELETE
- Fetch: GET, POST, PUT, DELETE
Simple GET request with response type <any>
This sends an HTTP GET request to the npm api for a list of packages that belong to the @angular scope, then assigns the total returned in the response to the local property totalAngularPackages. The response type is set to <any> so it handle any properties returned in the response.
ngOnInit() {
this.http.get<any>('https://api.npms.io/v2/search?q=scope:angular').subscribe(data => {
this.totalAngularPackages = data.total;
})
}
Example Angular component at https://stackblitz.com/edit/angular-http-get-examples?file=app/components/get-request.component.ts
GET request with strongly typed response
This sends the same request as the above but sets the response type to a custom SearchResults interface that defines the expected response properties.
ngOnInit() {
this.http.get<SearchResults>('https://api.npms.io/v2/search?q=scope:angular').subscribe(data => {
this.totalAngularPackages = data.total;
})
}
...
interface SearchResults {
total: number;
results: Array<object>;
}
Example Angular component at https://stackblitz.com/edit/angular-http-get-examples?file=app/components/get-request-typed.component.ts
GET request with error handling
This sends a request to an invalid url on the npm api then assigns the error to the errorMessage component property and logs the error to the console.
The object passed to the request subscribe() method contains two callback functions, the next() function is called if the request is successful and the error() function is called if the request fails.
ngOnInit() {
this.http.get<any>('https://api.npms.io/v2/invalid-url').subscribe({
next: data => {
this.totalAngularPackages = data.total;
},
error: error => {
this.errorMessage = error.message;
console.error('There was an error!', error);
}
})
}
Example Angular component at https://stackblitz.com/edit/angular-http-get-examples?file=app/components/get-request-error-handling.component.ts
GET request with headers set
This sends the same request again with a couple of headers set, the HTTP Authorization header and a custom header My-Custom-Header.
The below headers are created as a plain javascript object, they can also be created with the HttpHeaders class, e.g. const headers = new HttpHeaders({ 'Authorization': 'Bearer my-token', 'My-Custom-Header': 'foobar' })
To set or update headers on an existing HttpHeaders object call the set() method, e.g. const headers = new HttpHeaders().set('Authorization', 'Bearer my-token')
ngOnInit() {
const headers = { 'Authorization': 'Bearer my-token', 'My-Custom-Header': 'foobar' }
this.http.get<any>('https://api.npms.io/v2/search?q=scope:angular', { headers }).subscribe(data => {
this.totalAngularPackages = data.total;
})
}
Example Angular component at https://stackblitz.com/edit/angular-http-get-examples?file=app/components/get-request-headers.component.ts
Prerequisites for making HTTP request from Angular
Before making HTTP requests from your Angular app you need to do a couple of things.
1. Add the HttpClientModule to the imports array of your AppModule like below on lines 3 and 10.
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule } from '@angular/common/http';
import { AppComponent } from './app.component';
@NgModule({
imports: [
BrowserModule,
HttpClientModule
],
declarations: [
AppComponent
],
bootstrap: [AppComponent]
})
export class AppModule { }
2. Import the HttpClient into your component and add it to the constructor() params like below on lines 2 and 8.
import { Component, OnInit } from '@angular/core';
import { HttpClient } from '@angular/common/http';
@Component({ selector: 'app', templateUrl: 'app.component.html' })
export class AppComponent implements OnInit {
totalAngularPackages;
constructor(private http: HttpClient) { }
ngOnInit() {
// Simple GET request with response type <any>
this.http.get<any>('https://api.npms.io/v2/search?q=scope:angular').subscribe(data => {
this.totalAngularPackages = data.total;
})
}
}
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