Error using redux saga, take(patternOrChannel): argument 8 is not valid channel or a valid pattern

Question

I'm trying to use redux saga library to capture some actions but I'm having this error when I run the app:

index.js:2178 uncaught at rootSaga at rootSaga at projectSaga at watchFetchRequest at takeEvery Error: take(patternOrChannel): argument 8 is not valid channel or a valid pattern at take (http://localhost:3000/static/js/bundle.js:84689:9) at takeEvery (http://localhost:3000/static/js/bundle.js:85993:94) at createTaskIterator (http://localhost:3000/static/js/bundle.js:85179:17) at runForkEffect (http://localhost:3000/static/js/bundle.js:85583:24) at runEffect (http://localhost:3000/static/js/bundle.js:85468:872) at next (http://localhost:3000/static/js/bundle.js:85348:9) at proc (http://localhost:3000/static/js/bundle.js:85303:3) at runForkEffect (http://localhost:3000/static/js/bundle.js:85587:19) at runEffect (http://localhost:3000/static/js/bundle.js:85468:872) at http://localhost:3000/static/js/bundle.js:85677:14 at Array.forEach () at runAllEffect (http://localhost:3000/static/js/bundle.js:85676:10) at runEffect (http://localhost:3000/static/js/bundle.js:85468:413) at next (http://localhost:3000/static/js/bundle.js:85348:9) at proc (http://localhost:3000/static/js/bundle.js:85303:3) at runForkEffect (http://localhost:3000/static/js/bundle.js:85587:19) at runEffect (http://localhost:3000/static/js/bundle.js:85468:872) at http://localhost:3000/static/js/bundle.js:85677:14 at Array.forEach () at runAllEffect (http://localhost:3000/static/js/bundle.js:85676:10) at runEffect (http://localhost:3000/static/js/bundle.js:85468:413) at next (http://localhost:3000/static/js/bundle.js:85348:9) at proc (http://localhost:3000/static/js/bundle.js:85303:3) at runSaga (http://localhost:3000/static/js/bundle.js:85858:76) at Object../src/store/ReduxRoot.tsx (http://localhost:3000/static/js/bundle.js:95823:16) at webpack_require (http://localhost:3000/static/js/bundle.js:679:30) at fn (http://localhost:3000/static/js/bundle.js:89:20) at Object../src/index.tsx (http://localhost:3000/static/js/bundle.js:95325:75) at webpack_require (http://localhost:3000/static/js/bundle.js:679:30) at fn (http://localhost:3000/static/js/bundle.js:89:20) at Object.0 (http://localhost:3000/static/js/bundle.js:96424:18) at webpack_require (http://localhost:3000/static/js/bundle.js:679:30) at ./node_modules/@babel/runtime/helpers/arrayWithoutHoles.js.module.exports (http://localhost:3000/static/js/bundle.js:725:37) at http://localhost:3000/static/js/bundle.js:728:10

This is the saga code:

import { all, call, fork, put, takeEvery } from 'redux-saga/effects';
import {  ActionType, Action, SearchCriteria } from '../model/types';
import { searchProjectsError, searchProjectsCompleted } from '../actions/projects';
import { API_URL } from '../../config';
// import axios from 'axios';

function callApi(method: string, url: string, path: string, data?: any) {
    return fetch(url  + path, {
      method,
      headers: {'Content-Type': 'application/json; charset=utf-8', 'Access-Control-Allow-Origin': '*'},
      body: JSON.stringify(data)
    }).then(res => res.json());
  }

// Here we use `redux-saga` to trigger actions asynchronously. `redux-saga` uses something called a
// "generator function", which you can read about here:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function*

function* handleFetch(action: Action<SearchCriteria>) {
  try {
    // To call async functions, use redux-saga's `call()`.
    const res = yield call(callApi, 'get', API_URL , '/api/DocumentLoader/GetProjects/', action.payload);

    if (res.error) {
      yield put(searchProjectsError(res.error));
    } else {
      yield put(searchProjectsCompleted(res));
    }
  } catch (err) {
    if (err instanceof Error) {
      yield put(searchProjectsError(err.stack!));
    } else {
      yield put(searchProjectsError('An unknown error occured.'));
    }
  }
}

// This is our watcher function. We use `take*()` functions to watch Redux for a specific action
// type, and run our saga, for example the `handleFetch()` saga above.
function* watchFetchRequest() {
  yield takeEvery(ActionType.SEARCH_PROJECTS, handleFetch); // I think the error is here
}

// We can also use `fork()` here to split our saga into multiple watchers.
function* projectSaga() {
  yield all([fork(watchFetchRequest)]);
}

export default projectSaga;

I already tried to find an answer here in SO, but the only I could find was this post, but ActionType is been exported. I think the problem is with the parameter of handleFetch function

This is the action:

export function searchProjects(criterias: SearchCriteria): Action<SearchCriteria> {
    return {
        type: ActionType.SEARCH_PROJECTS,
        payload: criterias
    };
}

Another thing it could be is maybe I did something wrong at the time to compose the saga middleware:

const sagaMiddleware = createSagaMiddleware();

var middleware = applyMiddleware(logger, thunk, sagaMiddleware);

if (process.env.NODE_ENV === 'development') {
    middleware = composeWithDevTools(middleware);
}

// Here we use `redux-saga` to trigger actions asynchronously. `redux-saga` uses something called a
// "generator function", which you can read about here:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function*
export function* rootSaga() {
    yield all([fork(projectSaga)]);
  }
// running the root saga, and return the store object.
 sagaMiddleware.run(rootSaga);

I also tried removing the action parameter from handleFetch and the error is still happening

Does this answer your question? Redux-saga get data from action returns patternOrChannel is undefined — Michael Freidgeim
– Michael Freidgeim, Commented Jun 26, 2020 at 5:35

ocuenca · Accepted Answer · 2018-10-05 18:42:38Z

14

I found what was the error, the problem was the definition of ActionType enum. It was without assigning an string value for each action.

export const enum ActionType {

// Projects
SEARCH_PROJECT,
SEARCH_PROJECTS_COMPLETED,
SEARCH_PROJECTS_ERROR,

}

This fixed the problem:

export const enum ActionType {

// Projects
SEARCH_PROJECTS= '@@projects/SEARCH_PROJECTS',
SEARCH_PROJECTS_COMPLETED= '@@projects/SEARCH_PROJECTS_COMPLETED',
SEARCH_PROJECTS_ERROR= '@@projects/SEARCH_PROJECTS_ERROR',

}

answered Oct 5, 2018 at 18:42

ocuenca

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1 Comment

jmargolisvt Over a year ago

In general, the error is the result of not assigning the action constant to a string.

Manoj Kumar · Accepted Answer · 2018-10-05 17:30:14Z

0

The only possible error could be this:

Check whether you have imported the { ActionType } object here, from the models file where you have defined your constants.

export function searchProjects(criterias: SearchCriteria): 
    Action<SearchCriteria> {
    return {
        type: ActionType.SEARCH_PROJECTS,
        payload: criterias
    };
}

edited Oct 5, 2018 at 17:30

answered Oct 5, 2018 at 17:09

Manoj Kumar

1769 bronze badges

7 Comments

ocuenca Over a year ago

but that is not what I'm doing in the watchFetchRequest function?

Manoj Kumar Over a year ago

Sorry, thats a mistake on my part. I did not notice that part of the code. I will try to come up with the solution.

ocuenca Over a year ago

About your update, take a look the line that shows the import: import { ActionType, Action, SearchCriteria } from '../model/types';

Manoj Kumar Over a year ago

you have to import the ActionType in the file where you have the searchProjects action as well. The ActionType has to be imported in both files.

ocuenca Over a year ago

I'm doing also that, I'm using typescript, If were an error of that kind, typescript would let me know

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