烧瓶 - 蓝图 - sqlalchemy - 不能将名称“db”导入到moles文件中

问题描述

我遇到了这个错误：

我是新来的bluprint，并有导入数据库到mydatabase.py文件，这是模型文件的问题。 / b>
$ b

我的项目树

  nikoofar / 
 run.py 
书架/ 
 __init__.py 
 mydatabase.py 
 main / 
 controllers.py 
 __init__.py 
  

run.py

  from bookshelf import app 
 
 if __name__ =='__main__'：
 app.run（debug = True，port = 8000）
  

bookshelf / intit .py

  from flask import从bookhelf.main中获取Flask 
。控制器从flask_sqlalchemy导入主
从mydatabase导入SQLAlchemy 
导入pmenu 
 
 $ b app =烧瓶（__ name__，instance_relative_config = True）
 db = SQLAlchemy（app）
 db.init_app（app）
 application.config ['SQLALCHEMY_DATABASE_URI'] ='mysql + pymysql：//用户名：密码@ localhost / databasename'
 
 app.config.from_object（'config'）
 
 app.register_blueprint（main，url_prefix ='/'）
  

bookshelf / main / controllers.py

  from flask import蓝图
 from bookshelf.mydatabase import * 
 from flask_sqlalchemy import SQLAlchemy 
 
 $ b main = Blueprint（'main'，__name__）
 
 
 @main （）/ $）
 def index（）：
g = pmenu.query.all（）
 print（g）
 returnok
  

从书架import db 返回，如果删除，错误将改为：
$ b

bookshelf / mydatabase.py



  db 
 
 class pmenu（db.Model）：
 __tablename__ ='p_menu'
 id = db.Column（db.Integer，primary_key = True）
 txt = db.Column（db.String（80），unique = True）
 link = db.Column（db.String（1024））
 def __init __（self，txt，link）：
 self.txt = txt 
 self.link = link 
 def __repr __（self）：
 return{'txt'：+ self.txt +，'link'：+ self .link +}
  

任何解决方案？


解决方案

这实际上是一个简单但令人沮丧的问题。问题是你正在导入 BEFORE 你正在 __ init__中创建 db 的实例.py

如果将导入移动到 db = SQLAlchemy（app） ，它将工作：

  from flask import Flask 
 $ b $ from flask_sqlalchemy import SQLAlchemy 
 
 app = Flask（__ name__）
 app.config ['SQLALCHEMY_DATABASE_URI'] ='mysql + pymysql：// uername：password @ localhost / test'
 
 db = SQLAlchemy（app ）
 
 from bookshelf.main.controllers import main＃<  - 在此移动
 
 app.register_blueprint（main，url_prefix ='/'）
  

I'm new in bluprint, and have problem with importing db into mydatabase.py file which is models file.

I've faced with this error:

The tree of my project

nikoofar/
    run.py
    bookshelf/
        __init__.py
        mydatabase.py
        main/
            controllers.py
            __init__.py

run.py

from bookshelf import app

if __name__ == '__main__':
    app.run(debug=True, port=8000)

bookshelf / intit.py

from flask import Flask
from bookshelf.main.controllers import main
from flask_sqlalchemy import SQLAlchemy
from mydatabase import pmenu


app = Flask(__name__, instance_relative_config=True)
db = SQLAlchemy(app)
db.init_app(app)
application.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://username:password@localhost/databasename'

app.config.from_object('config')

app.register_blueprint(main, url_prefix='/')

bookshelf / main / controllers.py

from flask import Blueprint
from bookshelf.mydatabase import *
from flask_sqlalchemy import SQLAlchemy


main = Blueprint('main', __name__)


@main.route('/')
def index():
    g = pmenu.query.all()
    print (g)
    return "ok"

The problem backs to from bookshelf import db, and if I delete that, the error will be changed to:

bookshelf / mydatabase.py

from bookshelf import db

class pmenu(db.Model):
    __tablename__ = 'p_menu'
    id = db.Column(db.Integer, primary_key=True)
    txt = db.Column(db.String(80), unique=True)
    link = db.Column(db.String(1024))
    def __init__(self, txt, link):
        self.txt = txt
        self.link = link
    def __repr__(self):
        return "{'txt': " + self.txt + ", 'link':" + self.link + "}"

Any solution?

解决方案

This is actually a simple, yet frustrating issue. The problem is you are importing main BEFORE you are creating the instance of db in your __init__.py

If move the import to after your db = SQLAlchemy(app), it will work:

from flask import Flask

from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql+pymysql://uername:password@localhost/test'

db = SQLAlchemy(app)

from bookshelf.main.controllers import main #<--move this here

app.register_blueprint(main, url_prefix='/')

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