使用 redux saga 时出错，take(patternOrChannel)：参数 8 不是有效通道或有效模式

Question

我正在尝试使用 redux saga 库来捕获一些操作，但是在运行应用程序时出现此错误：

index.js:2178 在 rootSaga 在 projectSaga 在 watchFetchRequest at takeEvery 的 rootSaga 中未被捕获 错误：take(patternOrChannel): 参数 8 不是有效的通道或有效的模式 ( http://localhost:3000/static/js/bundle。 js:84689:9 ) 在 takeEvery ( http://localhost:3000/static/js/bundle.js:85993:94 ) 在 createTaskIterator ( http://localhost:3000/static/js/bundle.js:85179: 17 ) 在 runForkEffect ( http://localhost:3000/static/js/bundle.js:85583:24 ) 在 runEffect ( http://localhost:3000/static/js/bundle.js:85468:872 ) 在 next ( http://localhost:3000/static/js/bundle.js:85348:9 ) 在 proc (http://localhost:3000/static/js/bundle.js:85303:3 ) 在 runForkEffect ( http://localhost:3000/static/js/bundle.js:85587:19 ) 在 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 ) 在 runEffect ( http://localhost:3000/static/js/bundle.js:85468:413 ) 在下一个 ( http://localhost:3000/static /js/bundle.js:85348:9 ) 在 proc ( http://localhost:3000/static/js/bundle.js:85303:3 ) 在 runForkEffect (http://localhost:3000/static/js/bundle.js:85587:19 ) 在 runEffect ( http://localhost:3000/static/js/bundle.js:85468:872 ) 在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 ) 在下一个 ( http://localhost:3000/static/js/bundle.js:85348:9 ) 在 proc ( http://localhost:3000/static /js/bundle.js:85303:3 ) 在 runSaga ( http://localhost:3000/static/js/bundle.js:85858:76 ) 在 Object../src/store/ReduxRoot.tsx (http://localhost:3000/static/js/bundle.js:95823:16 ) 在webpack_require ( http://localhost:3000/static/js/bundle.js:679:30 ) 在 fn ( http:// localhost:3000/static/js/bundle.js:89:20 ) 在 Object../src/index.tsx ( http://localhost:3000/static/js/bundle.js:95325:75 ) 在webpack_require ( http://localhost:3000/static/js/bundle.js:679:30 ) 在 fn ( http://localhost:3000/static/js/bundle.js:89:20 ) 在 Object.0 ( http: //localhost:3000/static/js/bundle.js:96424:18 ) 在webpack_require ( http://localhost:3000/static/js/bundle.js:679:30) 在 ./node_modules/@babel/runtime/helpers/arrayWithoutHoles.js.module.exports ( http://localhost:3000/static/js/bundle.js:725:37 ) 在http://localhost:3000/静态/js/bundle.js:728:10

这是传奇代码：

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;

我已经尝试在 SO 中找到答案，但我唯一能找到的是这篇文章，但ActionType已导出。我认为问题在于handleFetch函数的参数

这是行动：

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

另一件事可能是我在编写 saga 中间件时做错了：

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);

我还尝试从中删除操作参数handleFetch，但错误仍在发生

Answer 1

我发现了错误是什么，问题是ActionType枚举的定义。它没有为每个动作分配一个字符串值。

export const enum ActionType {

// Projects
SEARCH_PROJECT,
SEARCH_PROJECTS_COMPLETED,
SEARCH_PROJECTS_ERROR,

}

这解决了问题：

export const enum ActionType {

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

}