what is the difference between a task and an effect? I found the def of an effect: https://redux-saga.js.org/docs/basics/DeclarativeEffects.html essentially a json obj that will be run by the middleware.
Are you calling the generator functions tasks?
Ah nm, that is what it is
Hi @all, I'm having trouble deciding how to handle global errors on my sagas and I was unable to find an elegant solution to it. Currently all my sagas have a huge try block which sends errors to sentry in its catch block if there's any error. Can someone please suggest me any better solution for this? I even followed up a few issues on the GitHub repo and stackoverflow but unfortunately I couldn't find something I can say can be considered as best practice. So I wanted to know how everyone else handles this. Any help, advice or suggestion is appreciated! Thanks in advance and I hope everyone is having a nice day!
This doesn't surprise me, the nature of saga calls makes me think more of error catching on an individual basis. If you are hitting an api, then you'll have to deal with 400 etc. That type of thing should probably be dealt with on a case by case basis. If you are looking for a global catch-all, I found this in github: redux-saga/redux-saga#1672
It might correspond to your needs @rishichawda
Also, I'm using
apisauce for calls to my api server so everything in the requests part is handled very well right now. What I wanted to do is make sure I handle possible scenarios that might happen in the production which cannot be reproduced so well manually. Like what if there's an inconsistent state or what if the data is corrupted or what if something happens on put or call. I need to handle those errors too. I'm not concerned about anything breaking in the UI since I'm having error boundaries for them but I need to make sure everything works fine with sagas too. Right now I pretty much have one try catch block in every saga which kind of feels redundant and doesn't look pretty to me. So I was looking for an elegant way to do that.
How do you handle errors in your saga btw? @unflores
@rishichawda we catch them in individual sagas. For me that makes the most sense, anything that gets up to the mainSaga error handler is more of a "catastrophic" error, I don't want to handle it b/c I wasn't expecting it. I just want to log it somewhere so I can deal with it later. I treat it as equivilant to a 500 from an api.
@rishichawda I've been looking for something solid like this
What I'm currently facing though I think is unrelated... for some reason my takeLatest from one module is not responding to another's action fired I think
in my rootSaga I have
yield createRequestInstance(); yield watchRequests(); all([fork(duck1), fork(duck2)]);
and a forked task is just a forked task
you need to yield the all effect as well though
yield all([fork(duck1), fork(duck2)]);
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@rishichawda hey I hope this reply isn't too late, but you can have sagas call each other in a chain, so you can consolidate all your generic error handling in one place. For example, instead of takeEvery(GET_RESOURCE_ACTION, getResources) and have getResources call the api directly, you can have getResources handle composing parameters / handling api response. In the middle, getResources might yield call callAndHandleApiErrors which deals with figuring out which api-specific things you need like headers, endpoints, etc... and dealing with api-level response errors. And within callAndHandleApiErrors you might have yet another saga that does the actual fetch call itself, and handles network-level issues. For example, if you want to auto-retry an api call X amount of times, you might pass that as a parameter down to the fetch* saga which can handle retrying your api call, and if it fails X times then it can dispatch an error and return something to the callAndHandleApiErrors saga so that it knows that it can proceed (e.g. just return null or something).
Can someone explain how the saga middleware works under the hood? Like I understand how middlewares work and I understand what take/takeEvery ect does, but I don't understand how the saga middleware does its job of getting the actions to the right sagas. Or maybe point me to a resource that explains it?
In the documentation on task cancellation (https://redux-saga.js.org/docs/advanced/TaskCancellation.html), it shows how to test that a task was cancelled, but it seems to me to be waaay more important to test that the code in the task that actually does the real cancellation (if yield(cancelled) {abortController.abort()} for example) runs. But I haven't been able to figure out how you create a generator as a task and cancel it so that I can test this. I think I understand how to spy on the constructor for AbortController so I can look at what happened--I just have no clue how to make it happen in a test scenario. The code would normally get cancelled by takeLatest.
@harvester-klirk , if you're asking what I think you're asking, the action itself will be the argument, and you'll look at its properties to determine what you should do. In addition, you can get access to the state using select() to fill in any gaps.
For anyone else wanting to test the finally logic in a canceled saga, I found the answer here https://stackoverflow.com/questions/46166401/unit-testing-redux-saga-task-cancellation https://github.com/redux-saga/redux-saga/issues/266#issuecomment-216087030. Hope this helps someone
I'm not having any trouble running the tests, and think i might be getting other erors than you described
i get straight-up normal errors:
Error: /Users/aleksandervognildburkow/Projects/redux-saga/packages/core/types/ts3.5/channels.test.ts:24:1
ERROR: 24:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 32:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 45:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 47:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 51:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 56:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 58:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 82:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 90:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 99:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 112:1 expect TypeScript@next: Expected an error on this line, but found none.
ERROR: 116:1 expect TypeScript@next: Expected an error on this line, but found none.
In order for the execution exception of an effect to not affect the whole, I created a wrapper function. For example, the following adds safety to each effect, which solves the problem.
But if my effect is very large, it is very time consuming and not elegant to manually increase the safety. I want to know if there is any way, such as a loop function to automatically add safety to each effect, which makes the code more beautiful.
wrapper function
import { call } from 'redux-saga/effects';
export function safe(sagaFn) {
return function* (action) {
try {
return yield call(sagaFn, action);
} catch (e) {
console.error('[react-demo | Saga Unhandled Exception] This error should be fixed or do some pre check in saga effects function.');
console.error(e);
}
};
}saga.js
function* mySaga() {
yield takeEvery('USER_FETCH', safe(fetchUserEffects));
yield takeEvery('TEST_SAGA', safe(testSagaEffects));
yield takeEvery('TEST_SAGA', safe(testSagaEffects2));
}
@aleksanb
@aleksanb Just came across your message. Thanks for reaching out! The errors you were pointing out occurred because TS wasn't able to resolve some types and was using any type as a replacement. So this was actually highly related to the issue I had.
As I said in the PR, I finally found a way to debug and fix it and the PR got merged into master :tada: . Unfortunately, it doesn't seem to work on @Andarist machine and he's unable to release, not sure why. If you want to give it a try 🤷♂️ .
@Andarist whenever you feel like it, we can spend some time to try to figure out what's wrong. Just tell me.
Great to see this being released now.
I upgraded our local project, the only thing missing now is for us to get
const someresult = yield call(someTypedFunction) to work, but that's blocked on typescript adding more support, right?
This cant yet be expressed in TS
There has been discussion around adding eslint plugins with autofixer that would annotate those for u
