什么是“res”？和“req” Express 函数中的参数？

发布于 2024-10-12 06:23:40 字数 213 浏览 1 评论 0原文

在下面的 Express 函数中：

app.get('/user/:id', function(req, res){
    res.send('user' + req.params.id);
});

什么是 req 和 res？它们代表什么、意味着什么、有什么作用？

谢谢！

原文

In the following Express function:

app.get('/user/:id', function(req, res){
    res.send('user' + req.params.id);
});

What are req and res? What do they stand for, what do they mean, and what do they do?

Thanks!

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苹果你个爱泡泡 2024-10-19 06:23:40

req 是一个对象，其中包含有关引发事件的 HTTP 请求的信息。为了响应 req，您可以使用 res 发回所需的 HTTP 响应。

这些参数可以命名为任何名称。如果更清楚的话，您可以将该代码更改为：

app.get('/user/:id', function(request, response){
  response.send('user ' + request.params.id);
});

编辑：

假设您有这个方法：

app.get('/people.json', function(request, response) { });

请求将是一个具有如下属性的对象（仅举几例）：

request.url，其中当触发此特定操作
request.method 时，将是 "/people.json"，在这种情况下将是 "GET"，因此app.get() 调用。
request.headers 中的 HTTP 标头数组，包含 request.headers.accept 之类的项目，您可以使用它们来确定发出请求的浏览器类型、类型它可以处理的响应，无论它是否能够理解 HTTP 压缩等。
request.query 中的查询字符串参数数组（如果有）（例如 /people.json?foo =bar 将导致 request.query.foo 包含字符串 "bar")。

要响应该请求，您可以使用响应对象来构建响应。扩展 people.json 示例：

app.get('/people.json', function(request, response) {
  // We want to set the content-type header so that the browser understands
  //  the content of the response.
  response.contentType('application/json');

  // Normally, the data is fetched from a database, but we can cheat:
  var people = [
    { name: 'Dave', location: 'Atlanta' },
    { name: 'Santa Claus', location: 'North Pole' },
    { name: 'Man in the Moon', location: 'The Moon' }
  ];

  // Since the request is for a JSON representation of the people, we
  //  should JSON serialize them. The built-in JSON.stringify() function
  //  does that.
  var peopleJSON = JSON.stringify(people);

  // Now, we can use the response object's send method to push that string
  //  of people JSON back to the browser in response to this request:
  response.send(peopleJSON);
});

req is an object containing information about the HTTP request that raised the event. In response to req, you use res to send back the desired HTTP response.

Those parameters can be named anything. You could change that code to this if it's more clear:

app.get('/user/:id', function(request, response){
  response.send('user ' + request.params.id);
});

Edit:

Say you have this method:

app.get('/people.json', function(request, response) { });

The request will be an object with properties like these (just to name a few):

request.url, which will be "/people.json" when this particular action is triggered
request.method, which will be "GET" in this case, hence the app.get() call.
An array of HTTP headers in request.headers, containing items like request.headers.accept, which you can use to determine what kind of browser made the request, what sort of responses it can handle, whether or not it's able to understand HTTP compression, etc.
An array of query string parameters if there were any, in request.query (e.g. /people.json?foo=bar would result in request.query.foo containing the string "bar").

To respond to that request, you use the response object to build your response. To expand on the people.json example:

app.get('/people.json', function(request, response) {
  // We want to set the content-type header so that the browser understands
  //  the content of the response.
  response.contentType('application/json');

  // Normally, the data is fetched from a database, but we can cheat:
  var people = [
    { name: 'Dave', location: 'Atlanta' },
    { name: 'Santa Claus', location: 'North Pole' },
    { name: 'Man in the Moon', location: 'The Moon' }
  ];

  // Since the request is for a JSON representation of the people, we
  //  should JSON serialize them. The built-in JSON.stringify() function
  //  does that.
  var peopleJSON = JSON.stringify(people);

  // Now, we can use the response object's send method to push that string
  //  of people JSON back to the browser in response to this request:
  response.send(peopleJSON);
});

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你对谁都笑 2024-10-19 06:23:40

我注意到戴夫·沃德的回答中有一个错误（也许是最近的变化？）：
查询字符串参数位于 request.query 中，而不是 request.params 中。（请参阅https://stackoverflow.com/a/6913287/166530）

request.params默认情况下填充路由中任何“组件匹配”的值，即

app.get('/user/:id', function(request, response){
  response.send('user ' + request.params.id);
});

，如果您已将express配置为使用其bodyparser（app.use(express.bodyParser());）也可以使用POST 后的表单数据。（请参阅如何检索 POST 查询参数？）

I noticed one error in Dave Ward's answer (perhaps a recent change?):
The query string paramaters are in request.query, not request.params. (See https://stackoverflow.com/a/6913287/166530 )

request.params by default is filled with the value of any "component matches" in routes, i.e.

app.get('/user/:id', function(request, response){
  response.send('user ' + request.params.id);
});

and, if you have configured express to use its bodyparser (app.use(express.bodyParser());) also with POST'ed formdata. (See How to retrieve POST query parameters? )

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