反应表示组件无法读取值 <input /> 来自redux商店使用反应容器

Question

I'm new to stackoverflow and quite new to using react/redux. I've been scanning over quite a few posts already to see if a similar post could provide me with an answer but I'm still left puzzled.

I currently have a presentational component "Repetitions" and a container component to get props from redux store and dispatch actions from the presentational component to redux store. I have the presentational component updating the redux store when I enter data into the input field but I am wanting to use the redux store to retrieve the input value so that when a user first comes on to the page the input value is "0" as that is the initial value inside the redux store.

I originally made a simple Counter component using react/redux and it was working ok. I have since made the "Repetition" component and altered the redux store to use a combinedreducer and this is when the problems seemed to start as neither components can read from the redux store.

Rootreducer.ts

import { combineReducers } from "redux";
import countReducer from "./example/reducer";
import repetitionsReducer from "./reps/reducer";

const rootReducer = combineReducers({
    countReducer,
    repetitionsReducer
})

export default rootReducer;

RepetitionsReducer.ts

import { RepetitionsState } from "../types";
import { AddRepetitionsAction } from "./actions";

export type RepetitionsActionType = AddRepetitionsAction;

export type Dispatch = (action: RepetitionsActionType) => void;

// The reducer updates the count
const initialState: RepetitionsState = {
  repetitions: 0
};

const repetitionsReducer = (
  state = initialState,
  action: RepetitionsActionType
): RepetitionsState => {
  switch (action.type) {
    case "ADD_REPETITIONS":
      return { ...state, repetitions: action.repetitions };
    default:
      return state;
  }
}

export default repetitionsReducer;

RepetitionsContainer.ts

import { connect } from "react-redux";
import { RootState } from "../../store/types";
import { Dispatch } from "../../store/reps/reducer";
import { addRepetitions } from "../../store/reps/actions";
import Repetitions from "../../components/reps/Repetitions";

interface StateFromProps {
  repetitions: number ;
}

interface DispatchFromProps {
  updateRepetitions: (repetitions: number) => void;
}

export type RepetitionsProps = StateFromProps & DispatchFromProps;

const mapStateToProps = (state: RootState): StateFromProps => ({
  repetitions: state.repetitions
});

const mapDispatchToProps = (dispatch: Dispatch): DispatchFromProps => ({
  updateRepetitions: (repetitions: number) => dispatch(addRepetitions(repetitions))
});

export default connect(
  mapStateToProps,
  mapDispatchToProps
)(Repetitions);

RepetitionsComponent.ts
note: When I try to console.log "repetitions" I am getting undefined at the moment.

import React from "react";
import { RepetitionsProps } from "../../containers/reps/Repetitions";

const Repetitions: React.FunctionComponent<RepetitionsProps> = ({ 
  repetitions, 
  updateRepetitions
}) => {
  console.log(repetitions)
  return (
    <div>
      <h3>Reps</h3>
      <input
        onChange={(event) => updateRepetitions(Number(event.target.value))}
        value={ repetitions } // <-- This is the value i'm wanting to present to the user from the redux store
      />                         
    </div>
  );
};

export default Repetitions;

App.ts

import React from "react";
import ReactDOM from "react-dom";
import * as serviceWorker from "./serviceWorker";
import Header from "./components/header/Header";
import { Provider } from "react-redux";
import { createStore } from "redux";
import Counter from "./containers/example/Counter";
import Repetitions from "./containers/reps/Repetitions";
import { composeWithDevTools } from 'redux-devtools-extension';
import rootReducer from "./store/reducer";

const store = createStore(rootReducer, composeWithDevTools());

console.log(store.getState())

function App() {
  return (
    <div className="App">
      <Header title={"Rep count"} />
      <Repetitions />
      <br />
      <br />
      <br />
      <Counter />
    </div>
  );
}


const rootElement = document.getElementById("root");
ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  rootElement
);

The expected results I would be hoping to see would be a "0" presented in the input box underneath the "Reps" header when a user first loads the page. Instead the box is empty but the redux store shows the value for repetitions as "0".

reps-input-desired-results

It is also worth noting that the counter below the input field used to read "0" from the redux store when I first loaded the page however now it is also undefined.

Thank you for taking the time to look at my post. Any help would be greatly appreciated!

Answer 1

Hmmm... something is wrong here:

First of all, your state for repetition is currently holding an object. It should hold a simple number.

Secondly, the name of the repetition state on the store (from the snapshot you've attached) is "repetitionReducer" and not "repetition" as you try to fetch it in mapStateToProps:

const mapStateToProps = (state: RootState): StateFromProps => ({
  repetitions: state.repetitions // <- this one here...
});

Hope this helps :)