Angular2 Http Request
Hi I am trying to make a get request using the HTTP module in Angular2.
Everything compiles fine in Typescript (1.5), but Chrome shows the following error the in console:
EXCEPTION: Error during instantiation of EntryList!. ORIGINAL
EXCEPTION: TypeError: Cannot read property 'merge' of undefined
ORIGINAL STACKTRACE: TypeError: Cannot read property 'merge' of undefined
at mergeOptions (angular2.dev.js:27991)
at execute.Http.get (angular2.dev.js:28052)
at EntryService.getEntries (services.js:17)
at new EntryList (entry-list.js:20)
Services.ts
/// <reference path="../typings/angular2/angular2.d.ts" />
import { Http, Observable } from "angular2/angular2"
export class EntryService {
private _entries: Array<string>;
private _http : Http;
constructor() {
this._entries = ["test1", "test2", "test3"];
this._http = new Http;
}
get Entries() : Array<string> {
return this._entries;
}
getEntries()
{
console.log(this._http);
return this._http.get('http://localhost:53338/api/decisions')
.toRx()
.map((response) => {
response.json()
});
}
}
entry-list.ts
/// <reference path="../typings/angular2/angular2.d.ts" />
/// <reference path="../modules/services.ts" />
import { Component, View, NgFor } from "angular2/angular2"
import { EntryService } from "modules/services"
@Component({
selector: 'entry-list'
})
@View({
directives: [ NgFor ],
templateUrl: "../views/entry-list.html"
})
export class EntryList {
entries: Array<string>;
constructor(public service: EntryService) {
this.entries = this.service.Entries;
this.service.getEntries().subscribe((response) => {
console.log(response);
});
}
}
app.ts
/// <reference path="typings/angular2/angular2.d.ts" />
/// <reference path="components/entry-list.ts" />
/// <reference path="modules/services.ts" />
import { Component, View, bootstrap, NgFor } from "angular2/angular2"
import { EntryList } from "components/entry-list"
import { EntryService } from "modules/services"
@Component({
selector : "app",
bindings: [ EntryService ]
})
@View({
directives: [ EntryList ],
templateUrl: "views/app.html"
})
class App {
constructor() {
console.log('hit');
}
}
bootstrap(App);
index.html
<html>
<head>
<title>SCM</title>
<script src="https://github.jspm.io/jmcriffey/[email protected]/traceur-runtime.js"></script>
<script src="https://jspm.io/[email protected]"></script>
<script src="https://code.angularjs.org/2.0.0-alpha.34/angular2.dev.js"></script>
</head>
<body>
<app></app>
<script>System.import('app')</script>
</body>
</html>
I did look at the API documentation on the angular.io site, but can't see whats wrong.
UPDATE
Services.ts
/// <reference path="../typings/angular2/angular2.d.ts" />
import { Http, Observable, httpInjectables } from "angular2/angular2"
export class EntryService {
private _entries: Array<string>;
constructor(private http: Http) {
this._entries = ["test1", "test2", "test3"];
}
get Entries() : Array<string> {
return this._entries;
}
getEntries()
{
console.log(this.http);
return this.http.get('http://localhost:53338/api/decisions')
.toRx()
.map((response) => {
response.json()
});
}
}
entry-list.ts
/// <reference path="../typings/angular2/angular2.d.ts" />
/// <reference path="../modules/services.ts" />
import { Component, View, NgFor, Http, httpInjectables } from "angular2/angular2"
import { EntryService } from "modules/services"
@Component({
selector: 'entry-list',
bindings : [ Http, httpInjectables ]
})
@View({
directives: [ NgFor ],
templateUrl: "../views/entry-list.html"
})
export class EntryList {
entries: Array<string>;
constructor(public service: EntryService) {
this.entries = this.service.Entries;
this.service.getEntries().subscribe((response) => {
console.log(response);
});
}
}
app.ts
/// <reference path="typings/angular2/angular2.d.ts" />
/// <reference path="components/entry-list.ts" />
/// <reference path="modules/services.ts" />
import { Component, View, bootstrap, NgFor, Http, httpInjectables } from "angular2/angular2"
import { EntryList } from "components/entry-list"
import { EntryService } from "modules/services"
@Component({
selector : "app",
bindings: [ EntryService, Http, httpInjectables ]
})
@View({
directives: [ EntryList ],
templateUrl: "views/app.html"
})
class App {
constructor() {
console.log('hit');
}
}
bootstrap(App);
Without any changes into index.html
Edit: My services.ts file changes to get this working:
/// <reference path="../typings/angular2/angular2.d.ts" />
import { Injector, Http, httpInjectables } from "angular2/angular2"
export class EntryService {
private _entries: Array<string>;
private http: Http;
constructor() {
this._entries = ["test1", "test2", "test3"];
var injector = Injector.resolveAndCreate([
httpInjectables,
Http
]);
this.http = injector.get(Http);
}
get Entries() : Array<string> {
return this._entries;
}
getEntries()
{
return this.http.get('http://localhost:53338/api/decisions')
.toRx()
.map(response => response.json());
}
}
Answer
You should not instantiate Http yourself, instead get it injected :
public constructor(http : Http) {
this.http = http;
}
The documentation says :
Http is available as an injectable class, with methods to perform http requests.
Therefore I am not sure what is the result if you instantiate it yourself, but somehow it can't manage to do the get request due to some internals that are undefined.
Edit: Adding more sources.
@Injectable()
export class Http {
constructor(protected _backend: ConnectionBackend, protected _defaultOptions: RequestOptions) {}
/**
* Performs a request with `get` http method.
*/
get(url: string, options?: RequestOptionsArgs): EventEmitter {
return httpRequest(this._backend, new Request(mergeOptions(this._defaultOptions, options, RequestMethods.GET, url)));
}
}
Here I added a little part of the Http class from the github repo. You can see that _backend and _defaultOptions are given in the constructor which you don't give, and the method get() will build options for the request based on the options parameter and the _defaultOptions given in the constructor, since you provide none of these, I believe it crashes in the mergeOptions call that you can find here :
function mergeOptions(defaultOpts, providedOpts, method, url): RequestOptions {
var newOptions = defaultOpts;
if (isPresent(providedOpts)) {
// Hack so Dart can used named parameters
newOptions = newOptions.merge(new RequestOptions({
method: providedOpts.method,
url: providedOpts.url,
search: providedOpts.search,
headers: providedOpts.headers,
body: providedOpts.body,
mode: providedOpts.mode,
credentials: providedOpts.credentials,
cache: providedOpts.cache
}));
}
if (isPresent(method)) {
return newOptions.merge(new RequestOptions({method: method, url: url}));
} else {
return newOptions.merge(new RequestOptions({url: url}));
}
}
At the last if/else of the function. For more information the source file is located here.