The type 'Observable<Response>' does not include a property called 'map'

Question

The type 'Observable<Response>' does not include a property called 'map'

I recently started learning angular and npm, but encountered an error while trying to replicate some code from a source I found (linked here).

It seems like the error is related to my development environment, but I'm having trouble pinpointing the exact cause.

Below is the snippet of code causing the issue:

return this.http.get('api/cards.json')
 .map((response:Response) => <Card[]>response.json().data)
 .do(data=>console.log(data))
 .catch(this.handleError);

When I look at the .map function in Visual Studio Code, I receive the following error message:

ts Property 'map' does not exist on type 'Observable'

If I ignore this error and proceed to the browser, I encounter the same message.

This project was generated with angular-cli, running on Angular version 2.4.4. The server is up and running using the ng serve command.

I've tried doing some research:

property map does not exist on observable response in angular --> This didn't apply to me as I don't use Visual Studio 2015 and my VS Code is up to date.

Angular 2 2.0.0-rc.1 Property 'map' does not exist on type 'Observable<Response>' --> The solution involving tsc doesn't work for me even after installing TypeScript globally and restarting VS Code and the server.

Any insights on what might be causing this issue? It appears to be related to something being out of date, but I'm unsure of what needs updating or how to go about it.

javascript angularjs typescript npm visual-studio-code

Answer 1

Answer №1

In order to utilize the RxJs library in your module/component/service (whatever it may be), you need to reference it as the Observable type (which is returned from http.get) belongs to this library. The RxJs offers various operators such as map, catch, do, and more, but you must reference the appropriate files/modules containing them to use these functionalities.

The tutorials provided on the angular website offer a detailed explanation on how to work with Observable<T> and establish a reference mapping for commonly used methods like map within the RxJs library. By creating a central file that references the frequently used operators and types in the RxJs library, you can simply refer to this file whenever you want to implement those types, eliminating the need to add them repeatedly in every file throughout your project where they are needed.

For instance, here is an example file (named rxjs-operators.ts in this scenario) containing some commonly employed methods:

// Observable class extensions
import 'rxjs/add/observable/of';
import 'rxjs/add/observable/throw';

// Observable operators
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/debounceTime';
import 'rxjs/add/operator/distinctUntilChanged';
import 'rxjs/add/operator/do';
import 'rxjs/add/operator/filter';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/switchMap';

To integrate these methods into the file where you wish to use .map (or any other method), include the following line at the beginning:

import './rxjs-operators';

Answer 2

In order to utilize the RxJs library in your module/component/service (whatever it may be), you need to reference it as the Observable type (which is returned from http.get) belongs to this library. The RxJs offers various operators such as map, catch, do, and more, but you must reference the appropriate files/modules containing them to use these functionalities.

The tutorials provided on the angular website offer a detailed explanation on how to work with Observable<T> and establish a reference mapping for commonly used methods like map within the RxJs library. By creating a central file that references the frequently used operators and types in the RxJs library, you can simply refer to this file whenever you want to implement those types, eliminating the need to add them repeatedly in every file throughout your project where they are needed.

For instance, here is an example file (named rxjs-operators.ts in this scenario) containing some commonly employed methods:

// Observable class extensions
import 'rxjs/add/observable/of';
import 'rxjs/add/observable/throw';

// Observable operators
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/debounceTime';
import 'rxjs/add/operator/distinctUntilChanged';
import 'rxjs/add/operator/do';
import 'rxjs/add/operator/filter';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/switchMap';

To integrate these methods into the file where you wish to use .map (or any other method), include the following line at the beginning:

import './rxjs-operators';

The type 'Observable<Response>' does not include a property called 'map'

Answer №1

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