执行操作时redux出错：未捕获类型错误：无法读取未定义的属性“类型”

Question

Just new to React. I guess It's a basic question but I can't get why the reducer doesn't get fired or update the state:

My HomeView.js:

     ....
          const { localeChange, counter, locale } = this.props
            return (
               <div>
                  <button onClick={() => increment(7)}>Increment</button>
              <input type='text' value = {counter}/>
               .....
            </div>
        )

    const mapStateToProps = (state) => ({
      locale: state.locale,
      counter: state.counter
    })
    export default connect(mapStateToProps, {localeChange, increment})(HomeView)

My reducer (constant, action and reducer in the same file):

export const COUNTER_INCREMENT = 'COUNTER_INCREMENT'

export function increment (text) {
  return { type: COUNTER_INCREMENT, text }
}

export default function counterIncrement (state = 0, action) {
  switch (action.type) {
    case 'INCREMENT':
      return state + action.text
    default:
      return state
  }
}

And finally my "parent" reducer:

import { combineReducers } from 'redux'
import { routeReducer as router } from 'react-router-redux'
import locale from './modules/locale'
import counter from './modules/counter'

export default combineReducers({
  locale,
  router,
  counter
})

What I understand:

In my state I have a field named counter (it's there using redux dev tools). When I click the button I dispatch increment action, so I really should dispatch an action like this: {type: COUNTER_INCREMENT, text: 7}

However counterIncrement function (reducer) gets action as undefined: Uncaught type error: cannot read property 'type' of undefined . Any way I could debug this properly? I put a breakpoint in the reducer counterIncrement but doesn't get fired.

Answer 1

Redux validate that every action you trigger actually contains a type property.

My guess is that you're calling dispatch() with undefined. Your example code doesn't contains any dispatch calls, so I won't be able to help further - but my guess is that it'll be trivial to figure out. Either you call dispatch() with the wrong arguments, or your action creator doesn't return an object with a type property.

Side note (unrelated to your question), but your action creator type label doesn't match the one inside your reducer.