我正在使用Flask与Flask-SQLAlchemy和Flask-Migrate来创建应用程序,但是当我尝试创建迁移时,没有任何反应。
我在app/models.py
创建了两个表:
from flask import current_app
from . import db
class Student(db.Model):
__tablename__ = 'students'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(64), unique=True, nullable=False)
password_hash = db.Column(db.String(128))
def __init__(self, **kwargs):
super(Student, self).__init__(**kwargs)
def __repr__(self):
return '<Tutor {}>' % self.id
class Tutor(db.Model):
__tablename__ = 'tutors'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(64), unique=True, index=True)
password_hash = db.Column(db.String(128))
def __init__(self, **kwargs):
super(Tutor, self).__init__(**kwargs)
def __repr__(self):
return '<Student %r>' % self.id
然后我也有app/__init__.py
与以下代码:
from flask import Flask
from flask_bootstrap import Bootstrap
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
#from .models import User, Task, Project, UserProject
from config import config
bootstrap = Bootstrap()
db = SQLAlchemy()
migrate = Migrate()
def create_app(config_name='default'):
#print config_name.name
app = Flask(__name__)
app.config.from_object(config[config_name])
config[config_name].init_app(app)
bootstrap.init_app(app)
db.init_app(app)
migrate.init_app(app, db)
## Register the main blueprint for main app functionality
from .main import main as main_blueprint
app.register_blueprint(main_blueprint)
return app
和app.py
:
import os
from app import create_app, db
from app.models import Tutor, Student
app = create_app('default')
@app.shell_context_processor
def make_shell_context():
return dict(db=db, Tutor=Tutor, Student=Student)
我可以毫无问题地运行flask db init
,并使用以下输出创建迁移目录和所有必需的文件:
Creating directory /Users/Jasmine/projects/flask/flask-tutoring/migrations ... done
Creating directory /Users/Jasmine/projects/flask/flask-tutoring/migrations/versions ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/script.py.mako ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/env.py ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/README ... done
Generating /Users/Jasmine/projects/flask/flask-tutoring/migrations/alembic.ini ... done
Please edit configuration/connection/logging settings in '/Users/Jasmine/projects/flask/flask-tutoring/migrations/alembic.ini' before proceeding.
但是当我尝试运行flask db migrate
时,alembic无法检测到我在app/models.py
有桌子。我得到以下输出:
INFO [alembic.runtime.migration] Context impl SQLiteImpl.
INFO [alembic.runtime.migration] Will assume non-transactional DDL.
INFO [alembic.env] No changes in schema detected.
没有创建迁移脚本,就好像models.py
不存在一样。
如果这是一个重复的问题,请道歉,但我找不到另一个例子,即第一次迁移失败并且根本没有创建迁移脚本。
我已经尝试通过在shell中运行db.drop_all()
来检查是否已经在某处创建了一个表,但这似乎不是问题所在。
我想出了一种方法来解决这个问题,但我希望能更好地理解为什么会这样。
我将app.py
重新命名为flasktutor.py
并重新运行export FLASK_APP='flasktutor.py'
。随后迁移工作完美。
请有人解释为什么当文件被称为app.py
并且我使用export FLASK_APP='app.py'
时,迁移没有注册对架构的更改。
请确保您已经在migrate.init_app(app, db)
之前导入了模型(导师,学生......)