I have a situation when it would be really convenient to have a promise object as a part of the state. In short - there is a state which contains all the info which user gave in the question-answer mode and after some answer it would be nice to send a call, result of which will be needed after several more questions:
Q1 -> Q2 -> Q3 - -> Q4 - - -> Q5 -> Q6 -> Q7
\ - - Call to API - - /
Before Q7 I need to check result of call after Q3. It would be really easy to do with promise as a part of the state and then just subscribe to result.
But I have inner feeling that it should not happen. Is it ok to do it this way?
I don't think that my code will help to understand, so feel free to just ask questions if it's not clear.
You should not do that because serializing your state would not be possible anymore. How much of a problem that is, not sure, it might only break the devtools or some persistence/hydration library you are using or will use. But to stay true to redux and its simplicity, reduce your scenario to a single truth:
Is the current question past Q3 but still before Q7? I imagine a selector could determine that because the current question is surely part of the state already.
Has a request been made to fetch the data?
Based on that you send the request:
if (currentQuestion > 3 && currentQuestion < 7 && !isDataRequested) {
dispatch(callToApi()); // this sets isDataRequested to true.
}
This will work with persisting and hydrating the state.
You can use redux-promise middleware, Your actions will return you promise if that action is completed, in-flight or failed. So you can easily manage questions and make call exactly at the right time you needed based on the promise. I have a sample example in my github account which shall explain how to use it. Let know if you find it useful.
Below is suedo code
Action controller
export const action_CALL = () => {
return {
type: SOME_CALL,
payload: new Promise((resolve, reject) => {
let wait = setTimeout(() => {
resolve('DUMMY ... Few questions answered in x mins');
}, 2000)
}),
};
};
Reducer
export const countReducer = typeToReducer({
[SOME_CALL]: {
PENDING: (state, action) => ({
...state,
answered: false,
}),
REJECTED: (state) => ({
...state,
answered: false,
}),
FULFILLED: (state, action) => ({
answered: true,
callResponse: action.payload,
})
}
}, initState);
This approach will give you fine-grained control.
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 new in Redux and Jest and I am struggling on a problem. I want to write the test for this file:
eventListeners.js
import store from '#/store';
chrome.runtime.onMessage.addListener((request) => {
if (request.type === 'OAUTH_SESSION_RESTORED') {
store.dispatch(completeLogin());
}
});
I have this file:
eventListeners.test.js
it('dispatches completeLogin when OAUTH_SESSION_RESTORED received', () => {
// I have made a mock of `chrome.runtime.sendMessage` so the listener defined in eventListeners.js is called when doing that
chrome.runtime.sendMessage({ type: 'OAUTH_SESSION_RESTORED' });
// I want to test that store.dispatch got called
});
However I don't succeed to test that the dispatch method of the store is called.
What I have tried so far:
1) trying to mock directly the method dispatch of the store (eg. doing jest.spyOn(store, 'dispatch') , jest.mock('#/store')).
However nothing seems to work. I think it is because the store used in eventListeners.js is not the one in the specs. So, mocking it does not do anything
2) Using the redux-mock-store library, as described in https://redux.js.org/recipes/writing-tests .
Doing
const store = mockStore({})
chrome.runtime.sendMessage({ type: 'OAUTH_SESSION_RESTORED' });
expect(store.getActions()).toEqual([{ type: 'LOGIN_COMPLETE' }])
However, same issue (I guess): the store used in the spec is not the same as in the eventListeners.js . store.getActions() returns [].
Is there a good way to test that store.dispatch get called?
===================================
For now, what I do is that I subscribe to the store and I try to see if the store has change. As described in https://github.com/reduxjs/redux/issues/546
it('dispatches completeLogin when OAUTH_SESSION_RESTORED received', () => {
const storeChangedCallback = jest.fn()
store.subscribe(storeChangedCallback)
chrome.runtime.sendMessage({ type: 'OAUTH_SESSION_RESTORED' });
expect(storeChangedCallback).toHaveBeenCalled();
})
Is there a better way? Did I missed something?
Thank you for your answers.
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$.pipe(...))
Another possible reason is that if you used ng generate to create the module where you imported the Effects make sure it is imported in the App Module as the following command 'ng generate module myModule' will not add it to the app module.
I've got a pretty straight forward effect defined using the ngrx/effects library.
#Effect()
public Authorize$ = 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.
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')
});