将 class 个具有状态的组件转换为具有钩子的功能组件

Question

我很难将 class 组件转换为功能组件。我看过多个执行此任务的示例，但我仍然了解基础知识。我如何使用 useState 和 useEffect 挂钩将我的代码更改为功能组件，也许如果有人有一些资源我可以找到关于这个主题的最佳实践？这是我要转换的代码示例：

import React, { Component } from "react";
import { storeProducts, detailProduct } from "./data";

const ProductContext = React.createContext();
//Provider
//Consumer

class ProductProvider extends Component {
    state = {
        products: [],
        detailProduct: detailProduct
    };

    componentDidMount() {
        this.setProducts();
    }

    setProducts = () => {
        let tempProducts = [];
        storeProducts.forEach(item => {
            const singleItem = {...item};
            tempProducts = [...tempProducts, singleItem];
        })
        this.setState(() => {
            return {products: tempProducts }
        });
    };

    handleDetail = () => {
        console.log("hello from detail");
    };

    addToCart = () => {
        console.log("hello from addToCart");
    };
render() {
    return (
            <ProductContext.Provider value={{
                ...this.state,
                handleDetail: this.handleDetail,
                addToCart: this.addToCart
            }}>
                {this.props.children}
            </ProductContext.Provider>
    );
}
}

Answer 1

您必须在功能组件中使用 useContext 才能获取上下文。

const ctx = React.createContext();

function ProductProvider(props) {
  const [products, setProducts] = React.useState([]);
  const [detailProduct, setDetailProduct] = React.useState(detailProduct);
  const ProductContext = React.useContext(ctx);

  React.useEffect(() => {
    handleProducts();
  }, []);

  function handleProducts() {
    let tempProducts = [];
    storeProducts.forEach(item => {
      const singleItem = { ...item };
      tempProducts = [...tempProducts, singleItem];
    });

    setProducts(tempProducts);

    // it could simple be written as
    setProducts(storeProducts);
  }

  function handleDetail() {
    console.log("hello from detail");
  }

  function addToCart() {
    console.log("hello from addToCart");
  }

  return (
    <ProductContext.Provider
      value={{
        products,
        detailProduct,
        handleDetail,
        addToCart
      }}
    >
      {props.children}
    </ProductContext.Provider>
  );
}

Answer 2

我试过@Prateek Thapa 代码，但它向我显示未定义 ProviderContext 的错误。显示错误是因为在我的函数之后我有一个常量：
const ProductCounsumer = ProductContext.Consumer
不在函数中。
此外，我将 data.js 中的 const 名称更改为 'detailedProduct'，因为它与 useEffect 行中的 const 名称相同。因此，在这些更改之后，我有了这个没有错误的示例，但我仍然不确定它是否像它应该的那样工作。如果我有这个，这个可以在没有 useContext 的情况下工作吗：

import React, { useState, useEffect } from "react";
import { storeProducts, detailedProduct } from "./data";

const ProductContext = React.createContext();
//Provider
//Consumer

function ProductProvider(props) {
    const [products, setProducts] = useState([]);
    const [detailProduct, setDetailProduct] = useState(detailedProduct);

    useEffect(() => {
      handleProducts();
    }, []);

    function handleProducts() {
      let tempProducts = [];
      storeProducts.forEach(item => {
        const singleItem = { ...item };
        tempProducts = [...tempProducts, singleItem];
      });

      setProducts(tempProducts);

      setProducts(storeProducts);
    }

    function handleDetail() {
      console.log("hello from detail");
    }

    function addToCart() {
      console.log("hello from addToCart");
    }

    return (
      <ProductContext.Provider
        value={{
          products,
          detailProduct,
          handleDetail,
          addToCart
        }}
      >
        {props.children}
      </ProductContext.Provider>
    );
  }
const ProductConsumer = ProductContext.Consumer;

export { ProductProvider, ProductConsumer };

将 class 个具有状态的组件转换为具有钩子的功能组件

Converting class component with state to functional component with hooks

reactjs

react-hooks

react-functional-component