Flask错误：ImportError无法从“ app”中导入名称“ app”

如何解决Flask错误：ImportError无法从“ app”中导入名称“ app”

我刚刚开始学习Flask，并且正在构建我的第一个应用程序。我的想法是制作一个简单的应用程序，以便将其存储在SQLite的学生，班级和教师中。

为此，我只做了两个python文件： app.py->创建应用程序并定义路由 models.py->创建数据库模型以进行存储

以某种方式，当我尝试将应用程序导入模型时，出现此错误：

Traceback (most recent call last):
  File "/Users/thiago/coding/eu-decidi/lib/python3.7/site-packages/flask/cli.py",line 240,in locate_app
    __import__(module_name)
  File "/Users/thiago/coding/eu-decidi/app.py",line 6,in <module>
    from models import Student,Teacher,Meeting,stud_identifier
  File "/Users/thiago/coding/eu-decidi/models.py",line 1,in <module>
    from app import app
ImportError: cannot import name 'app' from 'app' (/Users/thiago/coding/eu-decidi/app.py)

只需将代码放在这里：

app.py：

from flask import Flask,render_template,request,url_for,redirect,flash
from flask_sqlalchemy import SQLAlchemy
from flask_wtf import FlaskForm
from wtforms import StringField,SubmitField
from wtforms.validators import DataRequired
from models import Student,stud_identifier

app = Flask(__name__) #application instance
app.config['SECRET_KEY']= 'my_secret'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///myDB.db' #path to database and its name
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False #supress warning of changes on database
db = SQLAlchemy(app) #database instance

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

@app.route('/students')
def students():
    return "Here are all our students"

@app.route('/teachers')
def teachers():
    return "Here are all our teachers"

@app.route('/classes')
def classes():
    return "Here are all our classes"

# app name 
@app.errorhandler(404) 
def not_found(e): 
  return "Page not found"

models.py：

from app import app
from app import db

stud_identifier = db.Table('stud_ident',db.Column('student',db.Integer,db.ForeignKey('student.student_id')),db.Column('meeting',db.ForeignKey('meeting.meeting_id'))
    )

class Student(db.Model):
    #__tablename__ = 'student'
    student_id = db.Column(db.Integer,primary_key = True) #primary Key column,automatically generated IDs
    student_name = db.Column(db.String(80),index = True,unique = False) #name of student
    student_surname = db.Column(db.String(100),unique = False) #surname of student
    student_phone = db.Column(db.Integer,index=True,unique = True) #student phone number
    student_email = db.Column(db.String(200),unique = True) #student email
    #RELATIONSHIPS
    meetings = db.relationship('Meeting',secondary=stud_identifier,backref=db.backref('students',lazy='dynamic'))
 
    def __repr__(self):
        return "Aluno: {} {},telefone: {}".format(self.student_name,self.student_surname,self.student_phone)

class Meeting(db.Model):
    #__tablename__='meeting'
    meeting_id = db.Column(db.Integer,primary_key =True)
    meeting_date = db.Column(db.Date,unique=False) #date of the meeting
    meeting_subject = db.Column(db.String(80),unique=False) #subject of the meeting (Aula 1,Aula 2,Aula 3)
    #RELATIONSHIPS
    teacher_id = db.Column(db.Integer,db.ForeignKey('teacher.teacher_id'))
    #meeting.students.append(student) -> vai somar um aluno na tabela de identificação
    

class Teacher(db.Model):
    #__tablename__='teacher'
    teacher_id = db.Column(db.Integer,primary_key =True)
    teacher_name = db.Column(db.String(80),unique = False) #name of Teacher
    teacher_surname = db.Column(db.String(100),unique = False) #surname of teacher
    teacher_phone = db.Column(db.Integer,unique = True) #teacher phone number
    teacher_email = db.Column(db.String(200),unique = True) #Teacher email
    #RELATIONSHIPS
    meetings = db.relationship('Meeting',uselist=False,backref='teacher')

以下是存储库： Repository

解决方法

创建一个主文件夹，将除“ app.py”文件之外的所有文件和文件夹移动到该主文件夹中。保存，然后运行。

乍一看，我想这可能是循环导入，因为models在定义app之前需要尝试导入app。但是，我确实想指出您的应用程序结构可以进行改进，以使应用程序更易于理解。这通常是我构建烧瓶应用程序的方式：

run.py（应用程序入口点）

venv（虚拟环境）

decidi（您的应用程序包，其中的每个.py文件都可以作为该包的模块导入）

----- __init__.py（Python会看到此文件名，并将整个文件夹视为包）

----- models.py

----- templates

---------- index.html

----- static（提供CSS和图像等静态文件）

在run.py中，这非常简单。它从应用程序包（在您的情况下为decidi）中导入应用程序。

from decidi import app

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

在decidi/__init__.py中，将您拥有的东西放入app.py中。请注意，必须在初始化db之后执行模型的导入，否则将导致循环导入。某些编辑器可能会自动移动导入，在这种情况下，您需要关闭该功能。

from flask import Flask,render_template,request,url_for,redirect,flash
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__) #application instance
app.config['SECRET_KEY']= 'my_secret'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///myDB.db' #path to database and its name
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False #supress warning of changes on database
db = SQLAlchemy(app) #database instance

from decidi.models import Student # DO NOT PUT THIS AT THE TOP

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

在decidi/models.py中，您可以直接从应用程序包中导入db，因为它位于程序包的__init__.py中。

from decidi import db

class Student(db.Model):
    #__tablename__ = 'student'
    student_id = db.Column(db.Integer,primary_key = True) #primary Key column,automatically generated IDs
    student_name = db.Column(db.String(80),index = True,unique = False) #name of student
    student_surname = db.Column(db.String(100),unique = False) #surname of student
    student_phone = db.Column(db.Integer,index=True,unique = True) #student phone number
    student_email = db.Column(db.String(200),unique = True) #student email
 
    def __repr__(self):
        return "Aluno: {} {},telefone: {}".format(self.student_name,self.student_surname,self.student_phone)

要运行该应用程序，请将CD插入run.py所在的目录，激活虚拟环境，然后简单地python3 run.py。

为简单起见，我只保留了大部分代码。但是要旨在那里。随时问我是否引起混乱。

Flask错误：ImportError无法从“ app”中导入名称“ app”

如何解决Flask错误：ImportError无法从“ app”中导入名称“ app”

解决方法

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