循环导入错误（Python Flask Sqlalchemy）

问题描述 投票：0回答：1

当我运行代码时，出现以下错误：

File "c:\Python\app.py", line 3, in <module>
    from user import db, Hasta  # import relevant classes and database from user.py
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "c:\Python\user.py", line 6, in <module>
    from app import app  # Import Flask app
    ^^^^^^^^^^^^^^^^^^^
  File "c:\Python\app.py", line 3, in <module>
    from user import db, Hasta  # Import relevant classes and database from user.py
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
ImportError: cannot import name 'db' from partially initialized module 'user' (most likely due to a circular import) (c:\Python\user.py)

即使我的 

user.py
和 
app.py
文件位于同一目录中，我也会收到 
circular loop import
错误。我尝试了各种方法但找不到它。你能帮助我吗。另外，虽然我研究了这个错误，但我做不到。

随附的代码是我的Python文件：

  1. app.py

    # app.py
from flask import Flask, render_template, request, redirect, url_for, flash
from flask_sqlalchemy import SQLAlchemy
from user import db, Hasta  # import relevant classes and database from user.py

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
app.config['SECRET_KEY'] = 'your_secret_key_here'

db.init_app(app)

@app.route('/')
def index():
    return render_template("index.html")

@app.route('/login', methods=['POST'])
def login():
    username = request.form['username']
    password = request.form['password']

    # Here we can use Patient class
    hasta = Hasta.query.filter_by(hasta_username=username, hasta_password=password).first()

    if hasta:
        flash('Giriş başarılı', 'success')
        return redirect(url_for('hello'))
    else:
        flash('Kullanıcı adı veya şifre hatalı!', 'error')
        return redirect(url_for('index'))

@app.route('/hello')
def hello():
    return 'Hello, world!'

if __name__ == "__main__":
    app.run(debug=True)


  2. user.py
    ：

    # user.py
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy import ForeignKey
from sqlalchemy.orm import relationship
from datetime import datetime

from app import db  # Import Flask app

class Admin(db.Model):
   admin_id = db.Column(db.Integer, primary_key=True)
   admin_username = db.Column(db.String(50), unique=True, nullable=False)
   admin_password = db.Column(db.String(100), unique=True, nullable=False)

   def __init__(self, admin_username, admin_password):
      self.admin_username = admin_username
      self.admin_password = admin_password

class Hasta(db.Model):
   hasta_id = db.Column(db.Integer, primary_key=True)
   hasta_username = db.Column(db.String(50), unique=True, nullable=False)
   hasta_password = db.Column(db.String(100), unique=True, nullable=False)
   hasta_name = db.Column(db.String(25), nullable=False)
   hasta_surname = db.Column(db.String(25), nullable=False)
   hasta_gender = db.Column(db.String(1), nullable=False)
   hasta_birth = db.Column(db.DateTime, nullable=False)
   hasta_tel = db.Column(db.String(16), nullable=False)
   hasta_adres = db.Column(db.String(100), nullable=False)
   hast_admID = db.Column(db.Integer, db.ForeignKey('admin.admin_id'))
   admin = relationship("Admin")

class Doktor(db.Model):
   doktor_id = db.Column(db.Integer, primary_key=True)
   doktor_username = db.Column(db.String(50), unique=True, nullable=False)
   doktor_password = db.Column(db.String(100), unique=True, nullable=False)
   doktor_name = db.Column(db.String(25), nullable=False)
   doktor_surname = db.Column(db.String(25), nullable=False)
   dok_admID = db.Column(db.Integer, db.ForeignKey('admin.admin_id'))
   admin = relationship("Admin")
   dok_hastaID = db.Column(db.Integer, db.ForeignKey('hasta.hasta_id'))
   hasta = relationship("Hasta")

class Randevu(db.Model):
   randevu_id = db.Column(db.Integer, primary_key=True)
   randevu_tar = db.Column(db.DateTime, nullable=False)
   randevu_saat = db.Column(db.Time, nullable=False)
   ran_HastID = db.Column(db.Integer, db.ForeignKey('hasta.hasta_id'))
   hasta = relationship("Hasta")
   ran_DokID = db.Column(db.Integer, db.ForeignKey('doktor.doktor_id'))
   doktor = relationship("Doktor")

class Rapor(db.Model):
   rapor_id = db.Column(db.Integer, primary_key=True)
   rapor_tar = db.Column(db.DateTime, nullable=False)
   rapor_Icer = db.Column(db.String(120), nullable=False)
   rap_hasID = db.Column(db.Integer, db.ForeignKey('hasta.hasta_id'))
   hasta = relationship("Hasta")
   rap_dokID = db.Column(db.Integer, db.ForeignKey('doktor.doktor_id'))
   doktor = relationship("Doktor")
   rap_admID = db.Column(db.Integer, db.ForeignKey('admin.admin_id'))
   admin = relationship("Admin")

# Uygulama bağlamı içinde veri eklemeyi deneyin
with db.app.app_context():
   # Tablolara veri ekleniyor
   admin1 = Admin(admin_username='ibardo', admin_password='yalova77')
   db.session.add(admin1)

   hasta1 = Hasta(hasta_username='gonul', hasta_password='malatya44', hasta_name='Gonul', hasta_surname='Dogan', hasta_gender='K', hasta_birth=datetime(1970, 11, 3), hasta_tel='5356741243', hasta_adres='ZaferMah. Malatya', admin=admin1)
   hasta2 = Hasta(hasta_username='mustafa', hasta_password='yalova77', hasta_name='Mustafa', hasta_surname='Dogan', hasta_gender='E', hasta_birth=datetime(1968, 1, 4), hasta_tel='5325468264', hasta_adres='GocmenMah. Yalova', admin=admin1)
   hasta3 = Hasta(hasta_username='rauf', hasta_password='eskisehir26', hasta_name='Rauf', hasta_surname='Dogan', hasta_gender='E', hasta_birth=datetime(1990, 3, 1), hasta_tel='5359856242', hasta_adres='Tepabasi Eskisehir', admin=admin1)
   db.session.add(hasta1, hasta2, hasta3)

   doktor1 = Doktor(doktor_username='pam', doktor_password='scranton', doktor_name='Pam', doktor_surname='Beesly', admin=admin1, hasta=hasta1)
   doktor2 = Doktor(doktor_username='jim', doktor_password='usajim', doktor_name='Jim', doktor_surname='Halpert', admin=admin1, hasta=hasta2)
   doktor3 = Doktor(doktor_username='mike', doktor_password='engmik', doktor_name='Mike', doktor_surname='Scott', admin=admin1, hasta=hasta3)
   db.session.add(doktor1, doktor2, doktor3)

   randevu1 = Randevu(randevu_tar=datetime(2024, 9, 8), randevu_saat=datetime(13, 0), hasta=hasta1, doktor=doktor1)
   randevu2 = Randevu(randevu_tar=datetime(2025, 4, 2), randevu_saat=datetime(12, 0), hasta=hasta2, doktor=doktor2)
   randevu3 = Randevu(randevu_tar=datetime(2024, 7, 1), randevu_saat=datetime(16, 0), hasta=hasta3, doktor=doktor3)
   db.session.add(randevu1, randevu2, randevu3)

   rapor1 = Rapor(rapor_tar=datetime(2024, 7, 3), rapor_Icer='None', hasta=hasta1, doktor=doktor1, admin=admin1)
   rapor2 = Rapor(rapor_tar=datetime(2024, 5, 2), rapor_Icer='None', hasta=hasta2, doktor=doktor2, admin=admin1)
   rapor3 = Rapor(rapor_tar=datetime(2024, 9, 1), rapor_Icer='None', hasta=hasta3, doktor=doktor3, admin=admin1)
   db.session.add(rapor1, rapor2, rapor3)

   db.session.commit()

Hasta在土耳其语中的意思是患者，我已经使用过多次

python flask sqlalchemy
1个回答
0
投票

您面临的错误（

ImportError: cannot import name 'db' from partially initialized module 'user'
）称为循环导入错误：

  • 从 
    app
    (
    db
    )
     导入
    user.py
  • 从 
    db
    (
    user
    )
     导入
    app.py

由此我们可以说，当再次从 

user
文件中的 
db
导入 
app.py
时，它会再次进入 
app
或 
app.py
文件导入应用程序，这会导致此循环错误

要解决此错误，您需要打破循环，具体方法如下。

  • 创建一个新的Python文件 - 

    stating.py
    ： 该文件将包含所有初始化内容。

    from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
app.config['SECRET_KEY'] = 'your_secret_key_here'

db = SQLAlchemy(app)

  • 更新

    user.py
    ：仅更改导入项目，因为我们已将其模式设置为
    stating.py
    。

    更改此：

    from app import db

    对此：

    from stating import db

  • 更新

    app.py
    ：由于我们已将
    db
    初始化移至
    stating.py
    ，请将其删除并将导入更改为从新位置导入

    from flask import Flask, render_template, request, redirect, url_for, flash
from extensions import db
from user import Hasta

app = Flask(__name__)
db.init_app(app)
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