takeEvery doesn't work when action type is a Symbol

[Zacqary]

When dispatching actions with a type equal to a Symbol, takeEvery throws TypeError: Cannot convert a Symbol value to a string.

const ACTION_TYPE = Symbol("ACTION_TYPE Debug String");

// Inside a saga
yield* takeEvery(ACTION_TYPE, sagaToYield); // Throws TypeError

However, using take works fine.

for (;;) {
    yield take(ACTION_TYPE);
    // Yield results...
}

[yelouafi]

The issue seems from here. String interpolation doesn't work for symbols

[yelouafi]

fixed by c9c63d9

[jscinoz]

Seems to still be an issue when pattern is an array of symbols; the following line throws with TypeError: Cannot convert a Symbol value to a string:

https://github.com/yelouafi/redux-saga/blob/master/src/internal/sagaHelpers.js#L64

[bvalosek]

(highly related question to this thread)

When using a action creator function with a toString property, currently that is preventing take from working (very similar to this issue).

eg

const login = credentials => {type: 'LOGIN', payload: credentials};
login.toString = () => 'LOGIN';


...

dispatch(login(creds));

...

take(login)

Or more specifically: https://github.com/acdlite/redux-actions

Is ensuring that take(pattern) calls String(pattern) like the above fixes something we could have as well?

[yelouafi]

@bvalosek What error do you get?

[bvalosek]

I realized that this can't be implemented without breaking BC with your API.

I was asking if, when passing in a function that overrides toString that it could be cast to a string when running the matcher... but that would break the current expectations when calling take(fn) (as it serves as a predicate filter in this case).

https://github.com/yelouafi/redux-saga/blob/master/src/internal/proc.js#L17

What I am doing now is that i've made a utility const takes = p => take(String(p)) to use in all the places where i have an action creator function that returns the action type when cast to a string. If you're open to having this be a built-in Effect then I can open a PR.

[thezanke]

I found my way here looking to see if there's a way to automatically call .toString() on a redux-actions actionCreator. If this was possible I could completely drop my action type constants file (since I don't need them for reducers with redux-actions).

I opened a new issue here with a suggested solution.

[iMoses]

Was this issue solved?

I'm new to redux-saga and I couldn't make it work until I figured that the problem was my types were Symbols. I get no errors, no warnings, but the middleware doesn't catch any of my actions as long as the type is a Symbol.

Are Symbols not supported or is this a bug?

The problem seems to originate in the proc.js file at the default matcher, in which the following comparison takes place:

input.type === String(pattern)

This could be easily fixed by checking if the type is a symbol and if so we shouldn't turn it into a string.

input.type === (typeof input.type === 'symbol' ? pattern : String(pattern))