express.js路由说明 [英] express.js routes explanation

问题描述

我正在查看 express.js 源代码，以了解如何将命名路由参数映射到 req.params 属性。

I was looking at express.js source code, to find out how it maps named route parameters to req.params properties.

对于那些不知道的人，您可以在 express.js 中定义具有命名参数的路由，使其可选，只允许具体格式（和更多）：

For those who don't know, in express.js you can define routes with named parameters, make them optional, only allow the ones with specific format (and more):

app.get("/user/:id/:name?/:age(\\d+)", function (req, res) {
    console.log("ID is", req.params.id);
    console.log("Name is", req.params.name || "not specified!");
    console.log("Age is", req.params.age);
});

我意识到这个功能的核心是一种称为 pathRegexp（） 在 lib / utils.js 。方法定义如下：

I realized that the heart of this functionality is a method called pathRegexp() defined in lib/utils.js. The method definition is as follows:

function pathRegexp(path, keys, sensitive, strict) {
    if (path instanceof RegExp) return path;
    if (Array.isArray(path)) path = '(' + path.join('|') + ')';
    path = path
        .concat(strict ? '' : '/?')
        .replace(/\/\(/g, '(?:/')
        .replace(/(\/)?(\.)?:(\w+)(?:(\(.*?\)))?(\?)?(\*)?/g, function (_, slash, format, key, capture, optional, star) {
            keys.push({ name: key, optional: !! optional });
            slash = slash || '';
            return ''
                + (optional ? '' : slash)
                + '(?:'
                + (optional ? slash : '')
                + (format || '') + (capture || (format && '([^/.]+?)' || '([^/]+?)')) + ')'
                + (optional || '')
                + (star ? '(/*)?' : '');
        })
        .replace(/([\/.])/g, '\\$1')
        .replace(/\*/g, '(.*)');
    return new RegExp('^' + path + '$', sensitive ? '' : 'i');
}

重要的部分是第7行正则表达式， /（\ /）？（\。 ）？（\w +）（？:( \（。*？\）））？（\？）？（\ *）？/ g 路径名称：

The important part is the regex on line 7, /(\/)?(\.)?:(\w+)(?:(\(.*?\)))?(\?)?(\*)?/g which groups the matched portions of pathname this way:

slash    
符号                       ;                        &NBSP ;                        &NBSP ;                        &NBSP ;                 &NBS p; 

slash     the / symbol                                                                                                                    

格式  
我不知道目的是什么这个，需要解释。                       ;              

key      
\w + ）在之后：符号          ;                        &NBSP ;                        &NBSP ;                

key       the word (ie. \w+) after the : symbol                                                                           

捕获
在键前面写的正则表达式。应该用括号括起来（例如（。\\d +））

capture a regex written in front of the key. Should be wrapped in parenthesis (ex. (.\\d+))

< kbd>可选
键后的？符号   &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;                

kbd>明星      
* 符号      &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBS磷;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;                 

star       the * symbol                                                                                                                     

并且回调处理程序从上面的组中构建正则表达式。

and the callback handler builds a regex from the groups above.

现在的问题是

我的理解如下：

(format || '') + (capture || (format && '([^/.]+?)' || '([^/]+?)'))

，所提到的正则表达式是

and the mentioned regex is,

如果你放一个 符号后面的斜杠组，并且不指定匹配条件（正则表达式包含在键之后的括号中），所生成的正则表达式与路径的其余部分匹配，直到它达到。或 / 符号。

if you put a . symbol after the slash group and don't specify a match condition (the regex wrapped in parenthesis after the key), the generated regex matches the rest of path until it gets to a . or / symbol.

那么有什么意义？

我问这个是因为：

1. 我想在我的应用程序，并希望在使用它之前充分了解它的工作原理。


2. 我没有在 express.js 文档中找到任何内容。


3. 我只是好奇：）

1. I want to extract and use this method in my app and want to fully understand how it works before using it.
2. I didn't find anything on express.js documentation about it.
3. I'm just curious :)

推荐答案

给定路径'/ path /：file。：ext'，考虑表达式之间的区别：

Given the path '/path/:file.:ext', consider the difference between the expressions:

// With 'format' checking
/^\/path\/(?:([^\/]+?))(?:\.([^\/\.]+?))\/?$/

// Without 'format' checking
/^\/path\/(?:([^\/]+?))(?:([^\/]+?))\/?$/

在第一种情况下，你结束作为

In the first case, you end up with params as

{
    file: 'file',
    ext: 'js'
}

但是没有格式检查，你最终可以这样：

but without the format checking, you end up with this:

{
    file: 'f',
    ext: 'ile.js'
}

这篇关于express.js路由说明的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！