redux-saga/es/internal/middleware.js

Saga middleware for Redux to handle Side Effects

function _objectWithoutProperties(obj, keys) { var target = {}; for (var i in obj) { if (keys.indexOf(i) >= 0) continue; if (!Object.prototype.hasOwnProperty.call(obj, i)) continue; target[i] = obj[i]; } return target; }

import { is, check, object, createSetContextWarning } from './utils';
import { emitter } from './channel';
import { ident } from './utils';
import { runSaga } from './runSaga';

export default function sagaMiddlewareFactory() {
  var _ref = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};

  var _ref$context = _ref.context,
      context = _ref$context === undefined ? {} : _ref$context,
      options = _objectWithoutProperties(_ref, ['context']);

  var sagaMonitor = options.sagaMonitor,
      logger = options.logger,
      onError = options.onError;


  if (is.func(options)) {
    if (process.env.NODE_ENV === 'production') {
      throw new Error('Saga middleware no longer accept Generator functions. Use sagaMiddleware.run instead');
    } else {
      throw new Error('You passed a function to the Saga middleware. You are likely trying to start a        Saga by directly passing it to the middleware. This is no longer possible starting from 0.10.0.        To run a Saga, you must do it dynamically AFTER mounting the middleware into the store.\n        Example:\n          import createSagaMiddleware from \'redux-saga\'\n          ... other imports\n\n          const sagaMiddleware = createSagaMiddleware()\n          const store = createStore(reducer, applyMiddleware(sagaMiddleware))\n          sagaMiddleware.run(saga, ...args)\n      ');
    }
  }

  if (logger && !is.func(logger)) {
    throw new Error('`options.logger` passed to the Saga middleware is not a function!');
  }

  if (process.env.NODE_ENV === 'development' && options.onerror) {
    throw new Error('`options.onerror` was removed. Use `options.onError` instead.');
  }

  if (onError && !is.func(onError)) {
    throw new Error('`options.onError` passed to the Saga middleware is not a function!');
  }

  if (options.emitter && !is.func(options.emitter)) {
    throw new Error('`options.emitter` passed to the Saga middleware is not a function!');
  }

  function sagaMiddleware(_ref2) {
    var getState = _ref2.getState,
        dispatch = _ref2.dispatch;

    var sagaEmitter = emitter();
    sagaEmitter.emit = (options.emitter || ident)(sagaEmitter.emit);

    sagaMiddleware.run = runSaga.bind(null, {
      context: context,
      subscribe: sagaEmitter.subscribe,
      dispatch: dispatch,
      getState: getState,
      sagaMonitor: sagaMonitor,
      logger: logger,
      onError: onError
    });

    return function (next) {
      return function (action) {
        if (sagaMonitor && sagaMonitor.actionDispatched) {
          sagaMonitor.actionDispatched(action);
        }
        var result = next(action); // hit reducers
        sagaEmitter.emit(action);
        return result;
      };
    };
  }

  sagaMiddleware.run = function () {
    throw new Error('Before running a Saga, you must mount the Saga middleware on the Store using applyMiddleware');
  };

  sagaMiddleware.setContext = function (props) {
    check(props, is.object, createSetContextWarning('sagaMiddleware', props));
    object.assign(context, props);
  };

  return sagaMiddleware;
}