UseSelector 状态未定义

Question

该页面不呈现，引用TypeError: state is undefined，追溯到SelectForm.js 中的这一行：const filter = useSelector(state => state.filter);。

我花了几个小时试图弄清楚我做错了什么。我试过 createSelector 但这没有用。我试过分派“获取初始状态”操作，但没有奏效。该组件被包装在提供者标签中。我不确定为什么我无法访问该州。在这一点上，我看不到任何我一直在研究它的缺陷。

代码片段

减速器.js

let initialState = {
    filter: {
        country: null,
        state: null,
        level: null,
        team: null
    },

    isDBConnecting: false, 
    isDBConnected: false, 
    isDBError: false 
}

const SelectorReducer = (state=initialState, action) => {
    switch (action.type) {        
        case 'DB_CONNECT_INIT':
            return {
                ...state,
                isDBConnecting: true,
                isDBConnected: false,
                isDBError: false,
            };
...
...
}

export default SelectorReducer;

动作.js

export const initializeDBConnection = () => {
    return {
        type: 'DB_CONNECT_INIT'
    }
};

父组件.js

import React from 'react';
import { createStore } from 'redux';
import { Provider } from 'react-redux'; //import provider to provide component access to the state

//Component imports
import SelectForm from './components/SelectForm'
import SelectorReducer from '.../reducer.js'

const SelectorStore = createStore(SelectorReducer);

const ParentComponent = () => {

    return (
        <div className="page-container">
            <div id="carousel">
                <div id="wrapper">
                    <Provider store={SelectorStore}>
                        <SelectForm />
                    </Provider>
                </div>
            </div>
    </div>
    )
}

SelectForm.js（子组件，包裹在上面的Provider标签中）

//IMPORTS
import React from 'react'; //import react
import { useSelector, useDispatch } from 'react-redux';

//COMPONENT IMPORTS
import FormGroup from '../FormGroup';
import { * as actions } from '.../actions.js';

const SelectForm = (props) => {

    //STATEFUL IMPORTS
    //filter
    const filter = useSelector(state => state.filter);

Answer 1

感谢@NicholasTower 在评论中的回答。我的减速器没有默认情况下

default: return state

把它放进去解决了这个问题。