Python SQLAlchemy create_all() 不创建表
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SQLAlchemy create_all() does not create tables
提问by Paul
I'm trying to integrate PostgreSQL and SQLAlchemy but SQLAlchemy.create_all() is not creating any tables from my models.
我正在尝试集成 PostgreSQL 和 SQLAlchemy，但 SQLAlchemy.create_all() 没有从我的模型中创建任何表。
My code:
我的代码：
from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql+psycopg2://login:pass@localhost/flask_app'
db = SQLAlchemy(app)
db.create_all()
db.session.commit()
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True)
email = db.Column(db.String(120), unique=True)
def __init__(self, username, email):
self.username = username
self.email = email
def __repr__(self):
return '<User %r>' % self.username
admin = User('admin', '[email protected]')
guest = User('guest', '[email protected]')
db.session.add(admin)
db.session.add(guest)
db.session.commit()
users = User.query.all()
print users
But I get this error: sqlalchemy.exc.ProgrammingError: (ProgrammingError) relation "user" does not exist
但我收到此错误： sqlalchemy.exc.ProgrammingError: (ProgrammingError) relation "user" does not exist
How can I fix this?
我怎样才能解决这个问题？
采纳答案by rocknrollnerd
You should put your model class before create_all()call, like this:
您应该在create_all()调用之前放置模型类，如下所示：
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql+psycopg2://login:pass@localhost/flask_app'
db = SQLAlchemy(app)
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True)
email = db.Column(db.String(120), unique=True)
def __init__(self, username, email):
self.username = username
self.email = email
def __repr__(self):
return '<User %r>' % self.username
db.create_all()
db.session.commit()
admin = User('admin', '[email protected]')
guest = User('guest', '[email protected]')
db.session.add(admin)
db.session.add(guest)
db.session.commit()
users = User.query.all()
print users
If your models are declared in a separate module, import them before calling create_all().
如果您的模型在单独的模块中声明，请在调用之前导入它们create_all()。
Say, the Usermodel is in a file called models.py,
说，User模型在一个名为的文件中models.py，
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql+psycopg2://login:pass@localhost/flask_app'
db = SQLAlchemy(app)
# See important note below
from models import User
db.create_all()
db.session.commit()
admin = User('admin', '[email protected]')
guest = User('guest', '[email protected]')
db.session.add(admin)
db.session.add(guest)
db.session.commit()
users = User.query.all()
print users
Important note:It is important that you import your models after initializing the dbobject since, in your models.py_you also need to import the dbobject from this module.
重要说明：在初始化db对象后导入模型很重要，因为在您的models.py_you 中还需要db从此模块导入对象。
