从运行的node.js应用程序确定项目根目录

r囧r小猫 2022-11-28 13:49 156阅读 0赞

本文翻译自：[Determine project root from a running node.js application][]

*Is there a better way than `process.cwd()` to determine the root directory of a running node.js process?* **有没有比`process.cwd()`更好的方法来确定正在运行的node.js进程的根目录？** *Something like the equivalent of `Rails.root` , but for Node.js.* **类似于`Rails.root` ，但适用于Node.js。** *I'm looking for something that is as predictable and reliable as possible.* **我正在寻找尽可能可预测和可靠的东西。**

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### \#1楼 ###

参考：[https://stackoom.com/question/H4Bo/从运行的node-js应用程序确定项目根目录][https_stackoom.com_question_H4Bo_node-js]

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### \#2楼 ###

*`__dirname` isn't a global;* **`__dirname`不是全局的；** *it's local to the current module so each file has its own local, different value.* **它在当前模块本地，因此每个文件都有其自己的本地值。**

*If you want the root directory of the running process, you probably do want to use `process.cwd()` .* **如果要运行的进程的根目录，则可能确实要使用`process.cwd()` 。**

*If you want predictability and reliability, then you probably need to make it a requirement of your application that a certain environment variable is set.* **如果需要可预测性和可靠性，则可能需要使您的应用程序要求设置某个环境变量。** *Your app looks for `MY_APP_HOME` (Or whatever) and if it's there, and the application exists in that directory then all is well.* **您的应用程序查找`MY_APP_HOME` （或其他），如果存在，并且该应用程序存在于该目录中，则一切正常。** *If it is undefined or the directory doesn't contain your application then it should exit with an error prompting the user to create the variable.* **如果未定义或目录不包含您的应用程序，则它应退出并出现错误提示用户创建变量。** *It could be set as a part of an install process.* **可以将其设置为安装过程的一部分。**

*You can read environment variables in node with something like `process.env.MY_ENV_VARIABLE` .* **您可以使用诸如`process.env.MY_ENV_VARIABLE`类的内容读取节点中的环境变量。**

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### \#3楼 ###

*1- create a file in the project root call it **settings.js*** **1-在项目根目录中创建一个文件，将其称为settings.js**

*2- inside this file add this code* **2-在此文件中添加此代码**

module.exports = {
        POST_MAX_SIZE : 40 , //MB
        UPLOAD_MAX_FILE_SIZE: 40, //MB
        PROJECT_DIR : __dirname
    };

*3- inside node\_modules create a new module name it "settings" and inside the module index.js write this code:* **3-在node\_modules内部创建一个新的模块名称，即“设置”，并在模块index.js内部编写以下代码：**

module.exports = require("../../settings");

*4- and any time you want your project directory just use* **4-以及您希望项目目录仅使用的任何时间**

var settings = require("settings");
    settings.PROJECT_DIR;

*in this way you will have all project directories relative to this file ;)* **这样，您将拥有与此文件相关的所有项目目录；）**

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### \#4楼 ###

*There are several ways to approach this, each with their own pros and cons:* **有几种方法可以解决此问题，每种方法各有利弊：**

## *require.main.filename* **require.main.filename** ##

*From [http://nodejs.org/api/modules.html][http_nodejs.org_api_modules.html] :* **来自[http://nodejs.org/api/modules.html][http_nodejs.org_api_modules.html] ：**

> *When a file is run directly from Node, `require.main` is set to its `module` .* **直接从Node运行文件时，将`require.main`设置为其`module` 。** *That means that you can determine whether a file has been run directly by testing `require.main === module`* **这意味着您可以通过测试`require.main === module`来确定文件是否已直接运行。**
> 
> *Because `module` provides a `filename` property (normally equivalent to `__filename` ), the entry point of the current application can be obtained by checking `require.main.filename` .* **由于`module`提供了`filename`属性（通常等效于`__filename` ），因此可以通过检查`require.main.filename`来获取当前应用程序的入口点。**

*So if you want the base directory for your app, you can do:* **因此，如果您想要应用程序的基本目录，则可以执行以下操作：**

var path = require('path');
    var appDir = path.dirname(require.main.filename);

### *Pros & Cons* **优点缺点** ###

*This will work great most of the time, but if you're running your app with a launcher like **pm2** or running **mocha** tests, this method will fail.* **在大多数情况下，这会很好用，但是如果您使用pm2之类的启动器运行应用程序或运行mocha测试，则此方法将失败。**

## *global.X* **全局X** ##

*Node has aa global namespace object called `global` — anything that you attach to this object will be available everywhere in your app.* **节点有一个名为`global`全局命名空间对象-您附加到此对象的所有对象都将在您的应用程序中随处可用。** *So, in your `index.js` (or `app.js` or whatever your main app file is named), you can just define a global variable:* **因此，在`index.js` （或`app.js`或主应用程序文件中的任何名称）中，您可以定义一个全局变量：**

// index.js
    var path = require('path');
    global.appRoot = path.resolve(__dirname);
    
    // lib/moduleA/component1.js
    require(appRoot + '/lib/moduleB/component2.js');

### *Pros & Cons* **优点缺点** ###

*Works consistently but you have to rely on a global variable, which means that you can't easily reuse components/etc.* **可以始终如一地工作，但是您必须依赖全局变量，这意味着您无法轻松地重用组件/等。**

## *process.cwd()* **process.cwd（）** ##

*This returns the current working directory.* **这将返回当前工作目录。** *Not reliable at all, as it's entirely dependent on what directory the process was launched **from** :* **完全不可靠，因为它完全取决于进程从哪个目录启动：**

$ cd /home/demo/
    $ mkdir subdir
    $ echo "console.log(process.cwd());" > subdir/demo.js
    $ node subdir/demo.js
    /home/demo
    $ cd subdir
    $ node demo.js
    /home/demo/subdir

## *app-root-path* **应用程序根路径** ##

*To address this issue, I've created a node module called **[app-root-path][]** .* **为了解决这个问题，我创建了一个名为[app-root-path][]的节点模块。** *Usage is simple:* **用法很简单：**

var appRoot = require('app-root-path');
    var myModule = require(appRoot + '/lib/my-module.js');

*The **[app-root-path][]** module uses several different techniques to determine the root path of the app, taking into account globally installed modules (for example, if your app is running in `/var/www/` but the module is installed in `~/.nvm/v0.xx/lib/node/` ).* **[app-root-path][]模块使用几种不同的技术来确定应用程序的根路径，同时考虑到全局安装的模块（例如，如果您的应用程序在`/var/www/`运行，但该模块在`~/.nvm/v0.xx/lib/node/`安装） `~/.nvm/v0.xx/lib/node/` ）。** *It won't work 100% of the time, but it's going to work in most common scenarios.* **它不会100％地起作用，但是可以在大多数常见情况下起作用。**

### *Pros & Cons* **优点缺点** ###

*Works without configuration in most circumstances.* **在大多数情况下无需配置即可工作。** *Also provides some nice additional convenience methods (see project page).* **还提供了一些不错的附加便利方法（请参阅项目页面）。** *The biggest con is that it won't work if:* **最大的缺点是，如果出现以下情况，它将不起作用：**

*  *You're using a launcher, like pm2* **您正在使用启动器，例如pm2**
 *  ***AND** , the module isn't installed inside your app's `node_modules` directory (for example, if you installed it globally)* **AND ，该模块未安装在您应用的`node_modules`目录中（例如，如果您是全局安装的）**

*You can get around this by either setting a `APP_ROOT_PATH` environmental variable, or by calling `.setPath()` on the module, but in that case, you're probably better off using the `global` method.* **您可以通过设置`APP_ROOT_PATH`环境变量或在模块上调用`.setPath()`解决此问题，但在这种情况下，最好使用`global`方法。**

## *NODE\_PATH environmental variable* **NODE\_PATH环境变量** ##

*If you're looking for a way to determine the root path of the current app, one of the above solutions is likely to work best for you.* **如果您正在寻找一种*确定*当前应用程序根路径的方法，则上述解决方案之一可能最适合您。** *If, on the other hand, you're trying to solve the problem of loading app modules reliably, I highly recommend looking into the `NODE_PATH` environmental variable.* **另一方面，如果您要解决可靠加载应用程序模块的问题，则我强烈建议您查看`NODE_PATH`环境变量。**

*Node's [Modules system][] looks for modules in a variety of locations.* **Node的[模块系统][Modules system]在各种位置查找模块。** *[One of these locations is wherever `process.env.NODE_PATH` points][One of these locations is wherever _process.env.NODE_PATH_ points] .* **[这些位置之一是`process.env.NODE_PATH`指向的位置][One of these locations is wherever _process.env.NODE_PATH_ points] 。** *If you set this environmental variable, then you can `require` modules with the standard module loader without any other changes.* **如果设置此环境变量，则可以`require`具有标准模块加载器的模块，而无需进行任何其他更改。**

*For example, if you set `NODE_PATH` to `/var/www/lib` , the the following would work just fine:* **例如，如果将`NODE_PATH`设置为`/var/www/lib` ，则可以很好地进行以下操作：**

require('module2/component.js');
    // ^ looks for /var/www/lib/module2/component.js

*A great way to do this is using `npm` :* **一个很好的方法是使用`npm` ：**

"scripts": {
        "start": "NODE_PATH=. node app.js"
    }

*Now you can start your app with `npm start` and you're golden.* **现在，您可以使用`npm start`来启动您的应用程序了，您就很高兴。** *I combine this with my [enforce-node-path][] module, which prevents accidentally loading the app without `NODE_PATH` set.* **我将其与我的`NODE_PATH` [\-node-path][enforce-node-path]模块结合使用，这可以防止在未设置`NODE_PATH`情况下意外加载应用程序。** *For even more control over enforcing environmental variables, see [checkenv][] .* **有关对执行环境变量的更多控制，请参见[checkenv][] 。**

***One gotcha:** `NODE_PATH` **must** be set **outside** of the node app.* **一个 `NODE_PATH` ： 必须在节点应用程序外部设置`NODE_PATH` 。** *You cannot do something like `process.env.NODE_PATH = path.resolve(__dirname)` because the module loader caches the list of directories it will search before your app runs.* **您无法执行类似`process.env.NODE_PATH = path.resolve(__dirname)`因为模块加载程序会在应用程序运行之前缓存将搜索的目录列表。**

***\[added 4/6/16\]** Another really promising module that attempts to solve this problem is [wavy][] .* **\[16年4月6日添加\]试图解决此问题的另一个非常有前途的模块是[波浪形的][wavy] 。**

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### \#5楼 ###

*All these "root dirs" mostly need to resolve some virtual path to a real pile path, so may be you should look at `path.resolve` ?* **所有这些“根目录”都需要将一些虚拟路径解析为真实的堆路径，因此您可能应该看看`path.resolve` ？**

var path= require('path');
    var filePath = path.resolve('our/virtual/path.ext");

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### \#6楼 ###

***Create a function in app.js*** **在app.js中创建一个函数**

`/*Function to get the app root folder*/`

var appRootFolder = function(dir,level){
        var arr = dir.split('\\');
        arr.splice(arr.length - level,level);
        var rootFolder = arr.join('\\');
        return rootFolder;
    }
    
    // view engine setup
    app.set('views', path.join(appRootFolder(__dirname,1),'views'));

[Determine project root from a running node.js application]: https://oldbug.net/q/H4Bo/Determine-project-root-from-a-running-node-js-application
[https_stackoom.com_question_H4Bo_node-js]: https://stackoom.com/question/H4Bo/%E4%BB%8E%E8%BF%90%E8%A1%8C%E7%9A%84node-js%E5%BA%94%E7%94%A8%E7%A8%8B%E5%BA%8F%E7%A1%AE%E5%AE%9A%E9%A1%B9%E7%9B%AE%E6%A0%B9%E7%9B%AE%E5%BD%95
[http_nodejs.org_api_modules.html]: http://nodejs.org/api/modules.html
[app-root-path]: https://github.com/inxilpro/node-app-root-path
[Modules system]: https://nodejs.org/api/modules.html
[One of these locations is wherever _process.env.NODE_PATH_ points]: https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders
[enforce-node-path]: https://github.com/inxilpro/enforce-node-path
[checkenv]: https://github.com/inxilpro/node-checkenv
[wavy]: https://github.com/kolodny/wavy