NodeJS useContext()返回未定义的值-

cld4siwp  于 2022-12-26  发布在  Node.js
关注(0)|答案(1)|浏览(141)

我有产品的上下文文件和状态文件。当我尝试在产品组件中使用该上下文时,它返回未定义的值

产品上下文.js

import { createContext } from "react";

const ProductContext = createContext();

export default ProductContext;

产品状态.js

import ProductContext from './productContext';
import { useState } from 'react';

const ProductState = (props) => {
  const productsInitial = [
    {
      "_id": "63a4cc857f40d0063116be5f",
      "user": "63a4cbfd7f40d0063116be5d",
      "title": "Cassava",
      "description": "On-demand sand castle construction expertise.",
      "imgURL": "null",
      "price": "30",
      "__v": 0
    },
    {
      "_id": "63a4ccad7f40d0063116be69",
      "user": "63a4cbfd7f40d0063116be5d",
      "title": "Soyabeans",
      "description": "On-demand sand castle construction expertise.",
      "imgURL": "null",
      "price": "30",
      "__v": 0
    }
  ]
  const [products, setProducts] = useState(productsInitial);
  // console.log(products);

  return (
    <>

      <ProductContext.Provider value={{ products, setProducts }}>
        {props.children}
      </ProductContext.Provider>
    </>
  )
}

export default ProductState;

产品组件.js(React组件)

import React, { useContext } from 'react';
import ProductContext from '../context/products/productContext';
import ProductItems from './ProductItems';

console.log(ProductContext);
const ProductComponent = () => {
    const context = useContext(ProductContext);
    const { products, setProducts } = context;
    return (
        <>
            <div className="col-lg-4 ">
                {products.map((product) => {
                    return <ProductItems product={products} />
                })}
            </div>
        </>
    )
}

export default ProductComponent;

这条线

const context = useContext(ProductContext);

在Products.js中组件返回未定义的值,因为ProductContext返回未定义的值

js81xvg6

js81xvg61#

使用上下文的组件必须使用ProductState组件 Package
如果不知道在哪里添加ProductState,可以在入口点文件中添加。

root.render((
  <ProductState>
    <App />
  </ProductState>
))

可以简化对象的分解

const { products, setProducts } = useContext(ProductContext);

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