引用Flask应用程序中的目录不起作用，除非路径是绝对路径 [英] Refering to a directory in a Flask app doesn't work unless the path is absolute

问题描述

我将nltk的数据下载到我的Flask应用程序的数据目录中。视图驻留在与数据目录相同级别的另一个目录中的蓝图中。在视图中，我试图设置数据的路径，但它不起作用。

  nltk.data。 path.append（'../ nltk_data /'）
  

这是行不通的。

  nltk.data.path.append（'/ home / username / myapp / app / nltk_data /'）
  

为什么第一个表单不起作用？如何正确地引用数据的位置？

解决方案

在Python中（和大多数语言），代码驻留在程序包与运行程序时的工作目录不同。所有的相对路径都是相对于当前的工作目录，而不是它写入的代码文件。所以，即使是从蓝图中也可以使用相对路径 nltk_data / 应用程序（或蓝图）上的 root_path 属性是指包应用程序（或蓝图）的目录。

  resource_path = os.path.join（app.root_path，'enltk_data '）
  

---

可能没有理由追加这个每次你打电话查看文件夹。我不是特别熟悉nltk，但是可能有一种方法来构造这个，所以当你创建你的应用程序的时候，你需要设置一次数据路径。

---

$ prefb =lang-none prettyprint-override> 项目/ app / blueprint
/ data

^加入root_path到达
^ app.root_path总是指向这里，无论哪里cwd是
^当前工作目录


I downloaded nltk data into the data directory in my Flask app. The views reside in a blueprint in another directory on the same level as the data directory. In the view I'm trying to set the path to the data, but it doesn't work.

nltk.data.path.append('../nltk_data/')

This doesn't work. If I use the whole path, it does work.

nltk.data.path.append('/home/username/myapp/app/nltk_data/')

Why does the first form not work? How can I refer to the location of the data correctly?

解决方案

In Python (and most languages), where the code resides in a package is different than what the working directory is when running a program. All relative paths are relative to the current working directory, not the code file it's written in. So you would use the relative path nltk_data/ even from a blueprint, or you would use the absolute path and leave no ambiguity.

The root_path attribute on an app (or blueprint) refers to the package directory for the app (or blueprint). Join your relative path to that to get the absolute path.

resource_path = os.path.join(app.root_path, 'enltk_data')

---

There's probably no reason to be appending this folder every time you call a view. I'm not familiar with nltk specifically, but there's probably a way to structure this so you set up the data path once when you create your app.

---

project    /    app    /    blueprint
                       /    data

                            ^ join with root_path to get here
                ^ app.root_path always points here, no matter where cwd is
^ current working directory

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