How to pass url arguments (query string) to a HTTP request on Angular?

Angular 6

You can pass in parameters needed for get call by using params:

this.httpClient.get<any>(url, { params: x });

where x = { property: "123" }.

As for the api function that logs "123":

router.get('/example', (req, res) => {
    console.log(req.query.property);
})

Version 5+

With Angular 5 and up, you DON'T have to use HttpParams. You can directly send your json object as shown below.

let data = {limit: "2"};
this.httpClient.get<any>(apiUrl, {params: data});

Please note that data values should be string, ie; { params: {limit: "2"}}

Version 4.3.x+

Use HttpParams, HttpClient from @angular/common/http

import { HttpParams, HttpClient } from '@angular/common/http';
...
constructor(private httpClient: HttpClient) { ... }
...
let params = new HttpParams();
params = params.append("page", 1);
....
this.httpClient.get<any>(apiUrl, {params: params});

Also, try stringifying your nested object using JSON.stringify().

The HttpClient methods allow you to set the params in it's options.

You can configure it by importing the HttpClientModule from the @angular/common/http package.

import {HttpClientModule} from '@angular/common/http';

@NgModule({
  imports: [ BrowserModule, HttpClientModule ],
  declarations: [ App ],
  bootstrap: [ App ]
})
export class AppModule {}

After that you can inject the HttpClient and use it to do the request.

import {HttpClient} from '@angular/common/http'

@Component({
  selector: 'my-app',
  template: `
    <div>
      <h2>Hello {{name}}</h2>
    </div>
  `,
})
export class App {
  name:string;
  constructor(private httpClient: HttpClient) {
    this.httpClient.get('/url', {
      params: {
        appid: 'id1234',
        cnt: '5'
      },
      observe: 'response'
    })
    .toPromise()
    .then(response => {
      console.log(response);
    })
    .catch(console.log);
  }
}

For angular versions prior to version 4 you can do the same using the Http service.

The Http.get method takes an object that implements RequestOptionsArgs as a second parameter.

The search field of that object can be used to set a string or a URLSearchParams object.

An example:

 // Parameters obj-
 let params: URLSearchParams = new URLSearchParams();
 params.set('appid', StaticSettings.API_KEY);
 params.set('cnt', days.toString());

 //Http request-
 return this.http.get(StaticSettings.BASE_URL, {
   search: params
 }).subscribe(
   (response) => this.onGetForecastResult(response.json()), 
   (error) => this.onGetForecastError(error.json()), 
   () => this.onGetForecastComplete()
 );

The documentation for the Http class has more details. It can be found here and an working example here.

Edit Angular >= 4.3.x

HttpClient has been introduced along with HttpParams. Below an example of use :

import { HttpParams, HttpClient } from '@angular/common/http';

constructor(private http: HttpClient) { }

let params = new HttpParams();
params = params.append('var1', val1);
params = params.append('var2', val2);

this.http.get(StaticSettings.BASE_URL, {params: params}).subscribe(...);

---

(Old answers)

Edit Angular >= 4.x

requestOptions.search has been deprecated. Use requestOptions.params instead :

let requestOptions = new RequestOptions();
requestOptions.params = params;

---

Original answer (Angular 2)

You need to import URLSearchParams as below

import { Http, RequestOptions, URLSearchParams } from '@angular/http';

And then build your parameters and make the http request as the following :

let params: URLSearchParams = new URLSearchParams();
params.set('var1', val1);
params.set('var2', val2);

let requestOptions = new RequestOptions();
requestOptions.search = params;

this.http.get(StaticSettings.BASE_URL, requestOptions)
    .toPromise()
    .then(response => response.json())
...