对象作为 React 子级无效(发现:[object Promise]) [英] Objects are not valid as a React child (found: [object Promise])

问题描述

我正在尝试通过数组映射来呈现帖子列表.我以前做过很多次，但出于某种原因

renderPosts = async() =>{尝试 {让 res = await axios.get('/posts');让帖子= res.data；返回 post.map((post, i) => {返回 (<li key={i} className="list-group-item>>{post.text}</li>);});} 捕捉(错误){控制台日志(错误)；}}使成为 () {返回 (
<ul className="list-group list-group-flush">{this.renderPosts()}</ul></div>);}

我得到的是:

<块引用>

未捕获的错误:对象作为 React 子项无效(找到:[object Promise]).如果您打算渲染一组子项，请改用数组.

我检查了从 renderPosts 返回的数据，它是一个具有正确值且没有任何承诺的数组.这是怎么回事?

解决方案

this.renderPosts() 将返回一个 Promise 而不是实际数据，AFAIK Reactjs 不会在 render 中隐式解析 Promise.

你需要这样做

componentDidMount() {this.renderPosts();}renderPosts = async() =>{尝试 {const res = await axios.get('/posts');常量帖子= res.data；//这将使用新数据重新渲染视图这个.setState({帖子:帖子});} 捕捉(错误){控制台日志(错误)；}}使成为() {const posts = this.state.Posts?.map((post, i) => (<li key={i} className="list-group-item>>{post.text}</li>));返回 (
<ul className="list-group list-group-flush">{帖子}</ul></div>);}

I am trying to render a list of posts by mapping through an array. I've done this many times before but for some reason

renderPosts = async () => {
    try {
      let res = await axios.get('/posts');
      let posts = res.data;
      return  posts.map((post, i) => {
        return (
          <li key={i} className="list-group-item">{post.text}</li>
        );
      });
    } catch (err) {
      console.log(err);
    }
  }

  render () {
    return (
      <div>
        <ul className="list-group list-group-flush">
          {this.renderPosts()}
        </ul>
      </div>
    );
  }

All I get is:

Uncaught Error: Objects are not valid as a React child (found: [object Promise]). If you meant to render a collection of children, use an array instead.

I've checked the data returned from renderPosts and it is an array with the correct values and no promises. What's going on here?

解决方案

this.renderPosts() will return a Promise not the actual data, and AFAIK Reactjs will not resolve Promises implicitly in render.

You need to do it like this

componentDidMount() {
  this.renderPosts();
}

renderPosts = async() => {
  try {
    const res = await axios.get('/posts');
    const posts = res.data;

    // this will re render the view with new data
    this.setState({
      Posts: posts
    });
  } catch (err) {
    console.log(err);
  }
}

render() {
  const posts = this.state.Posts?.map((post, i) => (
    <li key={i} className="list-group-item">{post.text}</li>
  ));

  return (
    <div>
      <ul className="list-group list-group-flush">
        {posts}
      </ul>
    </div>
  );
}

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