不变违规：对象作为React子对象无效 [英] Invariant Violation: Objects are not valid as a React child

问题描述

在我的组件的渲染功能中，我有：

In my component's render function I have:

render() {
    const items = ['EN', 'IT', 'FR', 'GR', 'RU'].map((item) => {
      return (<li onClick={this.onItemClick.bind(this, item)} key={item}>{item}</li>);
    });
    return (
      <div>
        ...
                <ul>
                  {items}
                </ul>
         ...
      </div>
    );
  }

一切都很好，但是当点击< li> 元素我收到以下错误：

everything renders fine, however when clicking the <li> element I receive the following error:

未捕获错误：不变违规：对象无效React
child（找到：带键的对象{dispatchConfig，dispatchMarker，
nativeEvent，target，currentTarget，type，eventPhase，bubbles，
cancelable，timeStamp，defaultPrevented，isTrusted，view，detail，
screenX，screenY，clientX，clientY，ctrlKey，shiftKey，altKey，
metaKey，getModifierState，button，buttons，relatedTarget，pageX，
pageY，isDefaultPrevented，isPropagationStopped，_dispatchListeners，
_dispatchIDs }）。如果你想渲染一个子集合，请使用数组，或者使用
的React附加组件中的createFragment（object）包装对象。检查欢迎的渲染方法。

如果我改为 this.onItemClick.bind（this，item） to （e）=> onItemClick（e，item）在map函数中，一切都按预期工作。

If I change to this.onItemClick.bind(this, item) to (e) => onItemClick(e, item) inside the map function everything works as expected.

如果有人可以解释我做错了什么并解释为什么我得到这个错误，会很好

If someone could explain what I am doing wrong and explain why do I get this error, would be great

UPDATE 1：

onItemClick函数如下所示，删除this.setState会导致错误消失。

UPDATE 1:
onItemClick function is as follows and removing this.setState results in error disappearing.

onItemClick(e, item) {
    this.setState({
      lang: item,
    });
}

但我无法删除此行，因为我需要更新此组件的状态

But I cannot remove this line as I need to update state of this component

推荐答案

我遇到了这个错误，结果发现我无意中在我的JSX代码中包含了一个我预期的对象成为字符串值：

I was having this error and it turned out to be that I was unintentionally including an Object in my JSX code that I had expected to be a string value:

return (
    <BreadcrumbItem href={routeString}>
        {breadcrumbElement}
    </BreadcrumbItem>
)

breadcrumbElement 曾经是一个字符串，但由于重构已成为一个Object。不幸的是，React的错误信息并没有很好地指出我存在问题的那一行。我必须一直跟着我的堆栈跟踪，直到我认识到传递给组件的道具然后我找到了有问题的代码。

breadcrumbElement used to be a string but due to a refactor had become an Object. Unfortunately, React's error message didn't do a good job in pointing me to the line where the problem existed. I had to follow my stack trace all the way back up until I recognized the "props" being passed into a component and then I found the offending code.

你会需要引用作为字符串值的对象的属性，或者将Object转换为所需的字符串表示。如果您确实想要查看对象的内容，则一个选项可能是 JSON.stringify 。

You'll need to either reference a property of the object that is a string value or convert the Object to a string representation that is desirable. One option might be JSON.stringify if you actually want to see the contents of the Object.

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