从外部文件访问配置变量

Question

我正在构建一个 Flask Web 应用程序，并且我正在实现一个用户可以上传自己的图像的功能。我正在处理三个文件来实现此功能：

• models.py：我在其中维护数据库结构和可在数据库中的实体上调用的函数的文件。

• routes.py：处理站点对各种 URL 上的 HTTP 请求的响应的文件。

• __init__.py：我所有的配置变量都在这里设置。

我在 models.py 中有一个名为 avatar 的函数，它返回用户的头像。如果他们没有上传照片，它会使用 gravatars MD5 哈希生成器生成头像。我想更改此功能，使其首先查看我的上传文件以查看用户是否上传了照片。

我已经设置了上传功能，这样用户的照片将保存在格式为 .. 的文件夹中。我有一个名为 UPLOAD_FOLDER 的配置变量，它存储该文件夹的绝对路径。但是，问题是无法从模型文件中访问配置变量。我已尝试按照docs 中的说明创建本地上下文，但遇到 KeyError: 'UPLOAD_FOLDER' 错误。

models.py

from flask import Flask, current_app
from hashlib import md5
class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key = True)
    username = db.Column(db.String(64), index = True, unique = True)
    email = db.Column(db.String(128), index = True, unique = True, nullable = False)
    password_hash = db.Column(db.String(128), nullable = False)
    is_admin = db.Column(db.Boolean(), default = False)
    polls = db.relationship("Poll", backref = "author", lazy = "dynamic")
    votes = db.relationship("Votes", backref = "voter", lazy = "dynamic")

   def avatar(self, size):
      app = Flask(__name__)
      with app.app_context():
      UPLOAD_FOLDER = current_app.config["UPLOAD_FOLDER"]
      if(UPLOAD_FOLDER):
         print("hooray")
      digest = md5(self.email.lower().encode("utf-8")).hexdigest()
      return(("https://www.gravatar.com/avatar/{}?d=retro&s={}").format(digest, size))

__init__.py

import os 

dirname = os.path.dirname(os.path.abspath(__file__))
UPLOAD_FOLDER = dirname + "/static/user-images/"
ALLOWED_FILES = ["png", "jpeg", "jpg"]

app = Flask(__name__)
app.config.from_object(Config)
app.config["UPLOAD_FOLDER"] = UPLOAD_FOLDER
app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 * 1024
app.config["ALLOWED_FILES"] = ALLOWED_FILES

routes.py

import os 
from werkzeug.utils import secure_filename
from flask_login import current_user

def allowed_file(file):
    return(file.filename.split(".")[1].lower() in app.config["ALLOWED_FILES"])

@app.route("/upload", methods = ["POST"])
@login_required
def upload_file():
    if(request.method == "POST"):
        if("file" not in request.files):
            print(request.files)
            flash("No file part")
            return(redirect("upload"))
        file = request.files["file"]
        if(not file.filename):
            flash("No file uploaded!")
            return(redirect("upload"))
        if(file and allowed_file(file)):
            extension = file.filename.split(".")[1]
            filename = secure_filename(str(current_user.id) + "." + extension)
            file.save(os.path.join(app.config["UPLOAD_FOLDER"], filename))
            flash("Files successfully uploaded")
            return(redirect(url_for("user", username = current_user.username)))

Answer 1

与其将配置变量推送到应用程序上下文，不如将它们放在配置文件中并在需要的地方导入它们？

创建一个名为 config.py 的文件

config.py

import os

dirname = os.path.dirname(os.path.abspath(__file__))

UPLOAD_FOLDER = dirname + "/static/user-images/"
ALLOWED_FILES = ["png", "jpeg", "jpg"]
MAX_CONTENT_LENGTH = 16 * 1024 * 1024

然后在 routes.py 中导入这些配置变量并使用它们，将app.config["UPLOAD_FOLDER"] 替换为UPLOAD_FOLDER

routes.py

import os 
from werkzeug.utils import secure_filename
from flask_login import current_user
from config import UPLOAD_FOLDER

def allowed_file(file):
    return(file.filename.split(".")[1].lower() in app.config["ALLOWED_FILES"])

@app.route("/upload", methods = ["POST"])
@login_required
def upload_file():
    if(request.method == "POST"):
        if("file" not in request.files):
            print(request.files)
            flash("No file part")
            return(redirect("upload"))
        file = request.files["file"]
        if(not file.filename):
            flash("No file uploaded!")
            return(redirect("upload"))
        if(file and allowed_file(file)):
            extension = file.filename.split(".")[1]
            filename = secure_filename(str(current_user.id) + "." + extension)
            file.save(os.path.join(UPLOAD_FOLDER, filename))
            flash("Files successfully uploaded")
            return(redirect(url_for("user", username = current_user.username)))

在models.py中做同样的事情，将current_app.config["UPLOAD_FOLDER"]替换为UPLOAD_FOLDER。

models.py

from flask import Flask, current_app
from hashlib import md5
from config import UPLOAD_FOLDER
class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key = True)
    username = db.Column(db.String(64), index = True, unique = True)
    email = db.Column(db.String(128), index = True, unique = True, nullable = False)
    password_hash = db.Column(db.String(128), nullable = False)
    is_admin = db.Column(db.Boolean(), default = False)
    polls = db.relationship("Poll", backref = "author", lazy = "dynamic")
    votes = db.relationship("Votes", backref = "voter", lazy = "dynamic")

   def avatar(self, size):
      app = Flask(__name__)
      with app.app_context():
          upload_folder = UPLOAD_FOLDER  # please don't make normal variables UPPERCASE
          if(upload_folder):
             print("hooray")
          digest = md5(self.email.lower().encode("utf-8")).hexdigest()
          return(("https://www.gravatar.com/avatar/{}?d=retro&s={}").format(digest, size))