React Native foreach循环 [英] React Native foreach loop

问题描述

我正在React Native中开发一个小应用程序，并且正在寻找诸如foreach函数之类的东西.我只是找不到foreach循环.不在StackOverflow上，甚至不在 docs 中.我已经找到了带有地图"的内容，但是我不知道这是否是我想要的.

I'm developing a little app in React Native and I am looking for something like a foreach function. I just can't find a foreach loop. Not on StackOverflow and not even in the docs. I've found something with 'map', but I don't know if this is what I'm looking for.

通过对服务器的请求，我获得了多个用户对象.当我记录结果时，它看起来像这样:

With a request to my Server I get multiple objects of users. When I log the result, it looks like this:

Object {
    "id": "1",
    "role": "user",
    "username": "user1",
  },
Object {
    "id": "2",
    "role": "admin",
    "username": "user2",

我想将其输出到列表中. 在普通的PHP中，我会为此使用一个foreach循环，但是就像我说的那样，我无法为React Native找到一个foreach循环.

I'd like to output this to a list. In plain PHP I would use a foreach loop for this, but like I said, I can't find a foreach loop for React Native.

如何循环遍历此对象?我知道我也可以使用简单的for循环，但这绝对不是我的首选...

How is it possible to loop trought this objects? I know that I could also use a simple for loop, but this would definitly not be my first choice...

我将此值与this.setState({users: responseData.users});保存在this.state.users中.状态是在我的构造函数中定义的.我尝试使用this.state.users.map(id => <Text>{id}</Text>)访问此文件，但始终收到相同的错误:null is not an object (evaluating 'this.state.users.map').我这样做正确吗?

I saved this value in this.state.users with this.setState({users: responseData.users});. State is defined in my constructor. I try to access this with this.state.users.map(id => <Text>{id}</Text>) but I always get the same error: null is not an object (evaluating 'this.state.users.map'). Am I doing this right?

推荐答案

您可以使用 for 或任何其他

You can use map or for-of or any other

示例:

// for of
for (let userObject of this.state.users) {
    console.log(userObject.username);
}
// map
this.state.users.map((userData) => {
    console.log(userData.username);
});

根据错误，您可能没有处于users状态的数据，因此您遇到了错误.如果数据正确，则上面的示例将正常工作

as per the error you may not have data within users state, so you are getting error. If data is proper then above example will work properly

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