[httprequest] Http post and get request in angular 6

In angular 5.2.x for http get and post I had this code:

post(url: string, model: any): Observable<boolean> {

return this.http.post(url, model)
  .map(response => response)
  .do(data => console.log(url + ': ' + JSON.stringify(data)))
  .catch(err => this.handleError(err));
 }
 get(url: string): Observable<any> {

return this.http.get(url)
  .map(response => response)
  .do(data =>
    console.log(url + ': ' + JSON.stringify(data))
  )
  .catch((error: any) => Observable.throw(this.handleError(error)));
 }

In angular 6 it doesn't work.

How can we make an HTTP post or get request?

For reading full response in Angular you should add the observe option:

{ observe: 'response' }

    return this.http.get(`${environment.serverUrl}/api/posts/${postId}/comments/?page=${page}&size=${size}`, { observe: 'response' });

You can do a post/get using a library which allows you to use HttpClient with strongly-typed callbacks.

The data and the error are available directly via these callbacks.

The library is called angular-extended-http-client.

angular-extended-http-client library on GitHub

angular-extended-http-client library on NPM

Very easy to use.

Traditional approach

In the traditional approach you return Observable<HttpResponse<T>> from Service API. This is tied to HttpResponse.

With this approach you have to use .subscribe(x => ...) in the rest of your code.

This creates a tight coupling between the http layer and the rest of your code.

Strongly-typed callback approach

You only deal with your Models in these strongly-typed callbacks.

Hence, The rest of your code only knows about your Models.

Sample usage

The strongly-typed callbacks are

Success:

• IObservable<T>
• IObservableHttpResponse
• IObservableHttpCustomResponse<T>

Failure:

• IObservableError<TError>
• IObservableHttpError
• IObservableHttpCustomError<TError>

Add package to your project and in your app module

import { HttpClientExtModule } from 'angular-extended-http-client';

and in the @NgModule imports

  imports: [
    .
    .
    .
    HttpClientExtModule
  ],

Your Models

export class SearchModel {
    code: string;
}

//Normal response returned by the API.
export class RacingResponse {
    result: RacingItem[];
}

//Custom exception thrown by the API.
export class APIException {
    className: string;
}

Your Service

In your Service, you just create params with these callback types.

Then, pass them on to the HttpClientExt's get method.

import { Injectable, Inject } from '@angular/core'
import { SearchModel, RacingResponse, APIException } from '../models/models'
import { HttpClientExt, IObservable, IObservableError, ResponseType, ErrorType } from 'angular-extended-http-client';
.
.

@Injectable()
export class RacingService {

    //Inject HttpClientExt component.
    constructor(private client: HttpClientExt, @Inject(APP_CONFIG) private config: AppConfig) {

    }

    //Declare params of type IObservable<T> and IObservableError<TError>.
    //These are the success and failure callbacks.
    //The success callback will return the response objects returned by the underlying HttpClient call.
    //The failure callback will return the error objects returned by the underlying HttpClient call.
    searchRaceInfo(model: SearchModel, success: IObservable<RacingResponse>, failure?: IObservableError<APIException>) {
        let url = this.config.apiEndpoint;

        this.client.post<SearchModel, RacingResponse>(url, model, 
                                                      ResponseType.IObservable, success, 
                                                      ErrorType.IObservableError, failure);
    }
}

Your Component

In your Component, your Service is injected and the searchRaceInfo API called as shown below.

  search() {    


    this.service.searchRaceInfo(this.searchModel, response => this.result = response.result,
                                                  error => this.errorMsg = error.className);

  }

Both, response and error returned in the callbacks are strongly typed. Eg. response is type RacingResponse and error is APIException.