javascript - react 类型错误 : x is not a function

Question

我从子组件中的父级调用函数“booksRefresh()”，但出现错误:

TypeError: booksRefresh is not a function

我不知道为什么，因为“booksRefresh”是一个函数。有人可以帮我解释为什么会发生这个错误吗？

这是我的代码:

import React, {useState} from "react";
import {Redirect} from "react-router";
import {addBook} from "../api/api";
import {Button} from "react-bootstrap";

const AddBookForm = (booksRefresh) => {
    const [title, setTitle] = useState();
    const [description, setDescription] = useState();
    const [submitted, setSubmitted] = useState(false);

    const postRequestHandler = () => {
        addBook(title, description);
        booksRefresh();
    }
...
 return (
        ...
            <Button type="submit" onClick={postRequestHandler} variant="outline-success">Add</Button>
        </div>
    )

家长:

function App({history}) {
  ...
    const [changeInBooks, setChangeInBooks] = useState(0)

    const booksRefresh = () => {
        let incrementChangeInBook = changeInBooks + 1;
        setChangeInBooks(incrementChangeInBook)
    }
return (
        <div className="App">
            <header className="App-header">
                ...
                            <Button variant="outline-success" onClick={() => history.push("/new-book")}>
                                {ADD_BOOK}</Button>
                ...
            </header>
            <Switch>
                ...
                <Route path="/new-book" exact render={() =>
                    <AddBookForm
                        booksRefresh={booksRefresh}/>
                }/>
               ...
            </Switch>
        </div>
    );
}

export default withRouter(App);

Answer 1

React 函数组件接收的参数是它的 Prop ，它是一个具有每个属性的命名属性的对象。所以你的AddBookForm的参数不应该是 booksRefresh , 但是(按照惯例)props , 然后通过 props.booksRefresh() 使用它:

const AddBookForm = (props) => {
// −−−−−−−−−−−−−−−−−−^^^^^
    const [title, setTitle] = useState();
    const [description, setDescription] = useState();
    const [submitted, setSubmitted] = useState(false);

    const postRequestHandler = () => {
        addBook(title, description);
        props.booksRefresh();
// −−−−−^^^^^^
    }

    // ...

或者如果它是唯一的 Prop ，你可以使用解构 as adiga shows :

const AddBookForm = ({booksRefresh}) => {