How to pass URLSearchParams in the HttpClient "get" method - Angular 5

Question

I used Angular 4.2 with the Http service and I used the get method like this where params is a URLSearchParams object:

this.http.get(url, {headers: this.setHeaders(), search: params})

I want to migrate to Angular 5. http is now a HttpClient object like recommended by the angular team. I got an error with the 'search' key.

Do you know how to migrate Http to HttpClient service in my case?

Thank you.

Answer 1

Since Angular 4.3 you can use HttpClient like this :

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

   constructor(private httpClient: HttpClient) { }    

   getData(){
        let headers = new HttpHeaders();
        headers  = headers.append('header-1', 'value-1');
        headers  = headers.append('header-2', 'value-2');

       let params = new HttpParams();
       params = params.append('param-1', 'value-1');
       params = params.append('param-2', 'value-2');

       this.httpClient.get("/data", {headers , params })
   }

HttpParams and HttpHeaders are immutable classes so after each call of set or append methods they return a new instance that's why you should do this : params = params.append(...)

Answer 2

Angular 4 Way:

this.http.get(url, {headers: this.setHeaders(), search: params})

Angular 5 Way:

import { HttpClient, HttpParams } from '@angular/common/http';
let params = new HttpParams().set('paramName', paramValue);
this.http.get(url,  { params: params })

Multiple Params:

// Initialize Params Object
let Params = new HttpParams();

// Begin assigning parameters
Params = Params.append('firstParameter', firstVal);
Params = Params.append('secondParameter', secondVal);

Answer 3

Following will be the changes, you need to do:

• Replace Older Http import with:

  import { HttpClient } from "@angular/common/http";

• Create HttpClient object as below:

  constructor( protected httpClient: HttpClient, ) {}

  Now there are ways to achieve search parameter namely as below:

  public get(searchParam: string): Observable { return this.httpClient.get(${this.URL}/${searchParam}); }

or:

public get(searchParam: string): Observable<object> {
let headers = new Headers({ 'Content-Type': 'application/json' });
    let myParams = HttpParams().set("id", searchParam);

    let options = new RequestOptions({ headers: headers, method: 'get', params: myParams });

return this.http.get("this.url",options)
         .map((res: Response) => res.json())
         .catch(this.handleError);
}