I've got a pretty straight forward effect defined using the ngrx/effects library.
#Effect()
public Authorize$ = this._actions$.ofType(IdentityActionsService.AUTHORIZE_IDENTITY)
.switchMap(action => this._svc.Authorize$(action.payload))
.catch(err => Observable.of(null).do(() => console.error(err); }))
.map(identity => this._identity.OnIdentityAuthorized(identity))
The #Effect is triggered, authorize$() runs, and the OnIdentityAuthorized() method, which returns an Action ({type: payload: }) fires...
What I expect to happen is that the action returned by OnIdentityAuthorized() should get fed into the appropriate reducer - that is not happening.
I have a debugger call in OnIdentityAuthorized and in the corresponding reducer. The Action returned by OnIdentityAuthorized is not being dispatched. What might cause this? Am I misunderstanding something?
I feel like what I've got is basically identical to example 1 here: https://github.com/ngrx/effects/blob/master/docs/intro.md
EDIT
Added additional code sections... The effect triggers the OnIdentityAuthorized debugger statement, so the observable is emitting all the way through the async authorization call. The reducer case is not triggered...
Here is the OnIdentityAuthorized() implementation:
public static ON_IDENTITY_AUTHORIZED = '[IDENTITY] Authorized';
public OnIdentityAuthorized(identity: Identity | JWT): Action {
debugger;
return {
type: IdentityActionsService.ON_IDENTITY_AUTHORIZED,
payload: identity
};
}
Here is the reducer section:
switch (action.type) {
case IdentityActionsService.ON_IDENTITY_AUTHORIZED:
debugger;
return merge({}, action.payload);
Turns out to have been an issue with the way I was registering the reducers.
I was trying to do something exotic in order to add additional state endpoints for lazy loaded modules... turns out there is an issue there - but that is a different question.
Related
All of my API calls are handled by redux-sagas. I'm creating a heartbeat modal in my app to detect inactivity. Each time a saga goes off I want to clear my setTimeout so I know that the user is active.
My middleware is a basic one at the moment:
const heartbeatMonitor => store => next => action {
if (action['##redux-saga/SAGA_ACTION']) {
clearTimeout(window.myTimeout);
}
window.myTimeout = window.setTimeout(function() {
// send off an action to tell user they are inactive
}, 100000);
}
It seems like looking for this symbol, ##redux-saga/SAGA_ACTION, is the only way to tell if the action is a saga. I see that redux-sagas has a createSagaMiddleware(options) and I tried using effectMiddlewares but it doesn't seem like you have access to the dispatch method in there so I can't send off a new actions.
but it doesn't seem like you have access to the dispatch method in there so I can't send off a new actions.
Not sure whether this is the kind of solution you wanted, but you do have access to the dispatch method where your comment // send off an action to tell user they are inactive is located in your code snippet, as it is exposed by the store object. (this is documented in the Store Methods Section of the store in the redux docs)
Therefore something like the following should satisfy your case:
const heartbeatMonitor => store => next => action {
if (action['##redux-saga/SAGA_ACTION']) {
clearTimeout(window.myTimeout);
}
const { dispatch } = store;
window.myTimeout = window.setTimeout(() => {
dispatch({ type: "USER_INACTIVE" });
}, 100000);
}
Note: I would probably implement this differently (using redux-sagas effects) Maybe this is an option for you too:
Example Saga
import { put, delay } from "redux-saga/effects";
function* inactiveSaga() {
yield delay(100000);
yield put({ type: "USER_INACTIVE" })
}
Example Integration of saga above:
(add the following in your root saga)
//import { takeLatest } from "redux-saga/effects";
takeLatest(() => true, inactiveSaga)
Explanation: Every action will trigger the inactiveSaga (cause () => true). The inactiveSaga will wait 100000ms before dispatching the "inactive action". If there is a new action within this waiting time the previous execution of the inactiveSaga will be canceled (cause takeLatest, see redux-saga effect docs for takeLatest) and started from the beginning again. (Therefore no "inactive action" will be sent and the inactiveSaga will start to wait for these 100000ms again, before being cancelled or completing the delay and dispatching the "inactive action")
I am having an issue with the ngrx store not dispatching an action to the effect supposed to deal with it.
Here is the component that tries to dispatch:
signin() {
this.formStatus.submitted = true;
if (this.formStatus.form.valid) {
this.store.dispatch(new StandardSigninAction(this.formStatus.form.value.credentials));
}
}
The actions:
export const ActionTypes = {
STANDARD_SIGNIN: type('[Session] Standard Signin'),
LOAD_PERSONAL_INFO: type('[Session] Load Personal Info'),
LOAD_USER_ACCOUNT: type('[Session] Load User Account'),
RELOAD_PERSONAL_INFO: type('[Session] Reload Personal Info'),
CLEAR_USER_ACCOUNT: type('[Session] Clear User Account')
};
export class StandardSigninAction implements Action {
type = ActionTypes.STANDARD_SIGNIN;
constructor(public payload: Credentials) {
}
}
...
export type Actions
= StandardSigninAction
| LoadPersonalInfoAction
| ClearUserAccountAction
| ReloadPersonalInfoAction
| LoadUserAccountAction;
The effect:
#Effect()
standardSignin$: Observable<Action> = this.actions$
.ofType(session.ActionTypes.STANDARD_SIGNIN)
.map((action: StandardSigninAction) => action.payload)
.switchMap((credentials: Credentials) =>
this.sessionSigninService.signin(credentials)
.map(sessionToken => {
return new LoadPersonalInfoAction(sessionToken);
})
);
I can see in debug that the component does call the dispatch method. I can also confirm that StandardSigninAction is indeed instantiated because the breakpoint in the constructor is hit.
But the standardSignin$ effect is not called...
What can possibly cause an effect not being called?
How can I debug what is going on within the store?
Can someone please help?
P.S. I do run the above effect as follows in my imports:
EffectsModule.run(SessionEffects),
edit: Here is my SessionSigninService.signin method (does return an Observable)
signin(credentials: Credentials) {
const headers = new Headers({'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8'});
const options = new RequestOptions({headers: headers});
const body = 'username=' + credentials.username + '&password=' + credentials.password;
return this.http.post(this.urls.AUTHENTICATION.SIGNIN, body, options).map(res => res.headers.get('x-auth-token'));
}
This is not going to be a definitive answer, but, hopefully, it will be helpful.
Before you start:
Make sure you are using the latest versions of the #ngrx packages (that are appropriate for the version of Angular you are using).
If you've updated any packages, make sure you re-start your development environment (that is, restart the bundler, the server, etc.)
If you've not done so already, you should have a look at the implementation of the Store - so that you make some educated guesses as to what could be going wrong. Note is that the Store is pretty light. It's both an observable (using the state as its source) and an observer (that defers to the dispatcher).
If you look at store.dispatch you'll see that it's an alias for
store.next, which calls next on the Dispatcher.
So calling:
this.store.dispatch(new StandardSigninAction(this.formStatus.form.value.credentials));
should just see an action emitted from the dispatcher.
The Actions observable that's injected into your effects is also pretty light. It's just an observable that uses the Dispatcher as its source.
To look at the actions that are flowing through the effect, you could replace this:
#Effect()
standardSignin$: Observable<Action> = this.actions$
.ofType(session.ActionTypes.STANDARD_SIGNIN)
with this:
#Effect()
standardSignin$: Observable<Action> = this.actions$
.do((action) => console.log(`Received ${action.type}`))
.filter((action) => action.type === session.ActionTypes.STANDARD_SIGNIN)
ofType is not an operator; it's a method, so to add do-based logging, it needs to be replaced with a filter.
With the logging in place, if you are receiving the action, there is something wrong with the effect's implementation (or maybe the action types' strings/constants aren't what you think they are and something is mismatched).
If the effect is not receiving the dispatched action, the most likely explanation would be that the store through which you are dispatching the StandardSigninAction is not that same store that your effect is using - that is, you have a DI problem.
If that is the case, you should look at what differs from the other SessionEffects that you say are working. (At least you have something working, which is a good place to start experimenting.) Are they dispatched from a different module? Is the module that dispatches StandardSigninAction a feature module?
What happens if you hack one of the working SessionEffects to replace its dispatched action with StandardSigninAction? Does the effect then run?
Note that the questions at the end of this answer aren't questions that I want answered; they are questions that you should be asking yourself and investigating.
Your store's stream may be stopping because of either unhandled errors or - perhaps more confusingly - errors that seem 'handled' using .catch that actually kill the stream without re-emitting a new Observable to keep things going.
For example, this will kill the stream:
this.actions$
.ofType('FETCH')
.map(a => a.payload)
.switchMap(query => this.apiService.fetch$(query)
.map(result => ({ type: 'SUCCESS', payload: result }))
.catch(err => console.log(`oops: ${err}`))) // <- breaks stream!
But this will keep things alive:
this.actions$
.ofType('FETCH')
.map(a => a.payload)
.switchMap(query => this.apiService.fetch$(query)
.map(result => ({ type: 'SUCCESS', payload: result }))
.catch(e => Observable.of({ type: 'FAIL', payload: e}))) // re-emit
This is true for any rxjs Observable btw, which is especially important to consider when broadcasting to multiple observers (like ngrx store does internally using an internal Subject).
I am using a later version of ngrx (7.4.0), so cartant's suggestion of:
.do((action) => console.log(`Received ${action.type}`))
should be...
... = this.actions.pipe(
tap((action) => console.log(`Received ${action.type}`)),
...
And in the end I discovered I had missed adding my new effects export to module, like:
EffectsModule.forRoot([AuthEffects, ViewEffects]), // was missing the ', ViewEffects'
If you are using version 8, ensure you wrap each action with createEffect.
Example:
Create$ = createEffect(() => this.actions$.pipe(...))
Another possible reason is that if you used ng generate to create the module where you imported the Effects make sure it is imported in the App Module as the following command 'ng generate module myModule' will not add it to the app module.
I feel like this scenario should be in the Angular 2 docs, but I can't find it anywhere.
Here's the scenario
submit a form (create object) that is invalid on the server
server returns a 400 bad request with errors I display on the form
after the subscribe comes back, I want to check an error variable or something (ie. if no errors > then route to newly created detail page)
I imagine it working something like this:
this.projectService.create(project)
.subscribe(
result => console.log(result),
error => {
this.errors = error
}
);
}
if (!this.errors) {
//route to new page
}
I'm very new to Angular 2 so this may come from my lack of understanding in how an Observable works. I have no issue with displaying that data on the form, but can't figure out how to see it within the ts component. I really just want to check the success/fail of the http create.
As stated in the relevant RxJS documentation, the .subscribe() method can take a third argument that is called on completion if there are no errors.
For reference:
[onNext] (Function): Function to invoke for each element in the observable sequence.
[onError] (Function): Function to invoke upon exceptional termination of the observable sequence.
[onCompleted] (Function): Function to invoke upon graceful termination of the observable sequence.
Therefore you can handle your routing logic in the onCompleted callback since it will be called upon graceful termination (which implies that there won't be any errors when it is called).
this.httpService.makeRequest()
.subscribe(
result => {
// Handle result
console.log(result)
},
error => {
this.errors = error;
},
() => {
// 'onCompleted' callback.
// No errors, route to new page here
}
);
As a side note, there is also a .finally() method which is called on completion regardless of the success/failure of the call. This may be helpful in scenarios where you always want to execute certain logic after an HTTP request regardless of the result (i.e., for logging purposes or for some UI interaction such as showing a modal).
Rx.Observable.prototype.finally(action)
Invokes a specified action after the source observable sequence terminates gracefully or exceptionally.
For instance, here is a basic example:
import { Observable } from 'rxjs/Rx';
import 'rxjs/add/operator/finally';
// ...
this.httpService.getRequest()
.finally(() => {
// Execute after graceful or exceptionally termination
console.log('Handle logging logic...');
})
.subscribe (
result => {
// Handle result
console.log(result)
},
error => {
this.errors = error;
},
() => {
// No errors, route to new page
}
);
Please note that the previous syntax with callbacks has been deprecated as of 6.4 and is going to be removed with 8.0. Instead of
of([1,2,3]).subscribe(
(v) => console.log(v),
(e) => console.error(e),
() => console.info('complete')
)
you should now use
of([1,2,3]).subscribe({
next: (v) => console.log(v),
error: (e) => console.error(e),
complete: () => console.info('complete')
})
https://rxjs.dev/deprecations/subscribe-arguments
You can achieve with following way
this.projectService.create(project)
.subscribe(
result => {
console.log(result);
},
error => {
console.log(error);
this.errors = error
}
);
}
if (!this.errors) {
//route to new page
}
Updated rxjs way 2022
this.projectService.create(project)
.subscribe({
next: (data)=>console.log('data',data),
error: (err)=>console.log('error',err),
complete:()=>console.log('complete')
});
I'm trying test my container component methods. My container had a async method that load all proposals and set in the state. Example.:
loadProposal(proposalId) {
return axios
.get("http://localhost:9292/api/proposal_drafts/1.json")
.then(response => {
this.setState({
proposal: Immutable.fromJS(response.data)
})
})
}
So, to test this method i get the component instance and call the method (the api url is mocked).
it("sets proposal in the state", (done) => {
const wrapper = shallow(<Container/>)
loadProposalRequest(1)
wrapper.instance().loadProposal(1).then(() => {
chai.expect(wrapper.state().proposal).to.be(Map)
done()
})
})
But i get this error from console:
Error: timeout of 2000ms exceeded. Ensure the done() callback is being
called in this test.
Ops: If i put a console.log(wrapper.state()) inside then() . The log shows my state correctly.
If chai.expect() throws an error (which I think is what's happening), two things will happen:
done won't get called, because of the thrown error;
the error won't get caught, because there's not additional error handling.
You should use Mocha's promise support instead to remove both issues:
it("sets proposal in the state", () => {
const wrapper = shallow(<Container/>)
loadProposalRequest(1)
return wrapper.instance().loadProposal(1).then(() => {
chai.expect(wrapper.state().proposal).to.be(Map)
})
})
You can also use chai-as-promised
you can write code that expresses what you really mean:
return doSomethingAsync().should.eventually.equal("foo");
or if you have a case where return is not preferable (e.g. style considerations) or not possible (e.g. the testing framework doesn't allow returning promises to signal asynchronous test completion), then you can use the following workaround (where done() is supplied by the test framework):
doSomethingAsync().should.eventually.equal("foo").notify(done);
Now, I have an initial page where I have three links. Once you click on the last 'friends' link, appropriate friends Component gets initiated. In there,
I want to fetch/get list of my friends strored into friends.json file.
Till now everything works fine. But I'm still a newbie for angular2's HTTP service using RxJs's observables, map, subscribe concept. I've tried to understand it and read few articles but until I get into practical work, I'm not gonna understand those concepts properly.
Here I have already made plnkr which is working except HTTP related work.
Plnkr
myfriends.ts
import {Component,View,CORE_DIRECTIVES} from 'angular2/core';
import {Http, Response,HTTP_PROVIDERS} from 'angular2/http';
import 'rxjs/Rx';
#Component({
template: `
<h1>My Friends</h1>
<ul>
<li *ngFor="#frnd of result">
{{frnd.name}} is {{frnd.age}} years old.
</li>
</ul>
`,
directive:[CORE_DIRECTIVES]
})
export class FriendsList{
result:Array<Object>;
constructor(http: Http) {
console.log("Friends are being called");
// below code is new for me. So please show me correct way how to do it and please explain about .map and .subscribe functions and observable pattern.
this.result = http.get('friends.json')
.map(response => response.json())
.subscribe(result => this.result =result.json());
//Note : I want to fetch data into result object and display it through ngFor.
}
}
Please guide and explain properly. I know it will be so beneficial to lots of new developers.
Here is where you went wrong:
this.result = http.get('friends.json')
.map(response => response.json())
.subscribe(result => this.result =result.json());
it should be:
http.get('friends.json')
.map(response => response.json())
.subscribe(result => this.result =result);
or
http.get('friends.json')
.subscribe(result => this.result =result.json());
You have made two mistakes:
1- You assigned the observable itself to this.result. When you actually wanted to assign the list of friends to this.result. The correct way to do it is:
you subscribe to the observable. .subscribe is the function that actually executes the observable. It takes three callback parameters as follow:
.subscribe(success, failure, complete);
for example:
.subscribe(
function(response) { console.log("Success Response" + response)},
function(error) { console.log("Error happened" + error)},
function() { console.log("the subscription is completed")}
);
Usually, you take the results from the success callback and assign it to your variable.
the error callback is self explanatory.
the complete callback is used to determine that you have received the last results without any errors.
On your plunker, the complete callback will always be called after either the success or the error callback.
2- The second mistake, you called .json() on .map(res => res.json()), then you called it again on the success callback of the observable.
.map() is a transformer that will transform the result to whatever you return (in your case .json()) before it's passed to the success callback
you should called it once on either one of them.
Concepts
Observables in short tackles asynchronous processing and events. Comparing to promises this could be described as observables = promises + events.
What is great with observables is that they are lazy, they can be canceled and you can apply some operators in them (like map, ...). This allows to handle asynchronous things in a very flexible way.
A great sample describing the best the power of observables is the way to connect a filter input to a corresponding filtered list. When the user enters characters, the list is refreshed. Observables handle corresponding AJAX requests and cancel previous in-progress requests if another one is triggered by new value in the input. Here is the corresponding code:
this.textValue.valueChanges
.debounceTime(500)
.switchMap(data => this.httpService.getListValues(data))
.subscribe(data => console.log('new list values', data));
(textValue is the control associated with the filter input).
Here is a wider description of such use case: How to watch for form changes in Angular.
There are two great presentations at AngularConnect 2015 and EggHead:
Observables vs promises - https://egghead.io/lessons/rxjs-rxjs-observables-vs-promises
Creating-an-observable - https://egghead.io/lessons/rxjs-creating-an-observable
RxJS In-Depth https://www.youtube.com/watch?v=KOOT7BArVHQ
Angular 2 Data Flow - https://www.youtube.com/watch?v=bVI5gGTEQ_U
Christoph Burgdorf also wrote some great blog posts on the subject:
http://blog.thoughtram.io/angular/2016/01/06/taking-advantage-of-observables-in-angular2.html
http://blog.thoughtram.io/angular/2016/01/06/taking-advantage-of-observables-in-angular2.html
In action
In fact regarding your code, you mixed two approaches ;-) Here are they:
Manage the observable by your own. In this case, you're responsible to call the subscribe method on the observable and assign the result into an attribute of the component. You can then use this attribute in the view for iterate over the collection:
#Component({
template: `
<h1>My Friends</h1>
<ul>
<li *ngFor="#frnd of result">
{{frnd.name}} is {{frnd.age}} years old.
</li>
</ul>
`,
directive:[CORE_DIRECTIVES]
})
export class FriendsList implement OnInit, OnDestroy {
result:Array<Object>;
constructor(http: Http) {
}
ngOnInit() {
this.friendsObservable = http.get('friends.json')
.map(response => response.json())
.subscribe(result => this.result = result);
}
ngOnDestroy() {
this.friendsObservable.dispose();
}
}
Returns from both get and map methods are the observable not the result (in the same way than with promises).
Let manage the observable by the Angular template. You can also leverage the async pipe to implicitly manage the observable. In this case, there is no need to explicitly call the subscribe method.
#Component({
template: `
<h1>My Friends</h1>
<ul>
<li *ngFor="#frnd of (result | async)">
{{frnd.name}} is {{frnd.age}} years old.
</li>
</ul>
`,
directive:[CORE_DIRECTIVES]
})
export class FriendsList implement OnInit {
result:Array<Object>;
constructor(http: Http) {
}
ngOnInit() {
this.result = http.get('friends.json')
.map(response => response.json());
}
}
You can notice that observables are lazy. So the corresponding HTTP request will be only called once a listener with attached on it using the subscribe method.
You can also notice that the map method is used to extract the JSON content from the response and use it then in the observable processing.
import { HttpClientModule } from '#angular/common/http';
The HttpClient API was introduced in the version 4.3.0. It is an evolution of the existing HTTP API and has it's own package #angular/common/http.
One of the most notable changes is that now the response object is a JSON by default, so there's no need to parse it with map method anymore .Straight away we can use like below
http.get('friends.json').subscribe(result => this.result =result);