javascript - React，将父级创建的引用传递给子级

Question

我正在重构我的代码，并且父级中有一些逻辑需要评估其子级拥有的所有输入的值。为此，我在父级中创建 4 个引用，并将它们作为 prop 传递给其子级。如下:

  // References (will be used in multiple functions)
  usernameInput = createRef(null);
  emailInput = createRef(null);
  passwordInput = createRef(null);
  repeatPasswordInput = createRef(null);

  ...

  render() {
     return (
        <View>
          <Form1 usernameInputRef={usernameInput} emailInputRef={emailInput} />
          <Form2 passwordInputRef={passwordInput} repeatPasswordInputRef={repeatPasswordInput} />
        </View>
     );
  }

在每个 child 身上，我都这样做:

  // This is Child1. For Child2 gonna be the same but with its props.
  const {
    usernameInputRef,
    emailInputRef,
  } = props;


  return (
     <>
       <TextInput
           ref={usernameInputRef}
           ...
        />
       <TextInput
           ref={emailInputRef}
        />
    </>
 );
  

当我尝试访问父节点中每个子节点的值时，问题就出现了......如果我这样做:

  const username = this.usernameInput.current.props.value; // <--- Works if the input is in the same component, and not in the child.
  
  console.log(username);

我得到“null”。

有什么想法吗？在将我的代码重构为多个组件之前，这是有效的......

更新

文本输入代码:

import React from "react";
import { View, StyleSheet } from "react-native";
import { TextInput as RNPTextInput, useTheme } from "react-native-paper";

const TextInput = forwardRef((props, ref) => {
  const { colors } = useTheme();

  let {
    placeholder,
    multiline,
    maxLength,
    secureTextEntry,
    color,
    icon,
    counter,
    onChange,
    onSubmit,
    onFocus,
    containerStyle,
  } = props;

  ...

  return (
    <>
      <View style={containerStyle || styles.inputContainer}>
        <RNPTextInput
          ref={ref}
          ...

Answer 1

有一个优雅的解决方案可以访问 child 的数据。只需将forwardRef 与useImperativeHandle Hook 结合起来即可。

这样做:

const TextInput = forwardRef((props, ref) => {
  useImperativeHandle(ref, () => ({
    getText() {
      return text;
    },
  }));

不要用以下方式访问文本:

 const username = this.usernameInput.current.props.value

您可以通过以下方式获得它:

const username = this.usernameInput.current.getText();

这是一个完整的示例:https://medium.com/@nugen/react-hooks-calling-child-component-function-from-parent-component-4ea249d00740