CODEWITHSUNDEEP
pythonsqlalchemy
Saige Zhang
Saige Zhang

Reputation: 787

sqlalchemy OperationalError

I just want to create a database table and write some data into it. But I found some errors and I have no any idea about solving these questions.I will appreciate it if someone can help me!

    # coding=utf-8
    from sqlalchemy import Column, Integer, String, BigInteger
    from sqlalchemy.ext.declarative import declarative_base
    Base = declarative_base()


    class User(Base):

        __tablename__ = 'users'

        id = Column(Integer(), primary_key=True)
        username = Column(String(30), unique=True, nullable=False)  
        password = Column(String, default='123456', nullable=False) 
        name = Column(String(30), nullable=False)  
        grade = Column(String(30))  
        emp_no = Column(BigInteger, unique=True, nullable=False)

    print User.__table__


    from sqlalchemy import create_engine
    from sqlalchemy.orm import sessionmaker
    from sqlalchemy.ext.declarative import declarative_base


    Base = declarative_base()
    Session = sessionmaker()
    engine = create_engine('sqlite:///:memory:', echo=True)
    Session.configure(bind=engine)
    session = Session()
    Base.metadata.create_all(engine)

    ed_user = User(name='ed', username='jack', password='123', emp_no=1, grade='1')
    #
    session.add(ed_user)
    #
    with session.no_autoflush:
       session.query(User).filter_by(name='ed').first()

Here are result and errors output:

    /usr/bin/python2.7 /home/pajamas/PycharmProjects/untitled5/data_generator.py
    users
    2017-07-30 17:56:28,903 INFO sqlalchemy.engine.base.Engine SELECT CAST('test plain returns' AS VARCHAR(60)) AS anon_1
    2017-07-30 17:56:28,904 INFO sqlalchemy.engine.base.Engine ()
    2017-07-30 17:56:28,904 INFO sqlalchemy.engine.base.Engine SELECT CAST('test unicode returns' AS VARCHAR(60)) AS anon_1
    2017-07-30 17:56:28,904 INFO sqlalchemy.engine.base.Engine ()
    2017-07-30 17:56:28,908 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
    sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such table: users [SQL: u'SELECT users.id AS users_id, users.username AS users_username, users.password AS users_password, users.name AS users_name, users.grade AS users_grade, users.emp_no AS users_emp_no \nFROM users \nWHERE users.name = ?\n LIMIT ? OFFSET ?'] [parameters: ('ed', 1, 0)]
    2017-07-30 17:56:28,909 INFO sqlalchemy.engine.base.Engine SELECT users.id AS users_id, users.username AS users_username, users.password AS users_password, users.name AS users_name, users.grade AS users_grade, users.emp_no AS users_emp_no 
    FROM users 
    WHERE users.name = ?
    LIMIT ? OFFSET ?
    2017-07-30 17:56:28,909 INFO sqlalchemy.engine.base.Engine ('ed', 1, 0)

    Process finished with exit code 1

Upvotes: 0

Views: 1905

Answers (2)

aristotll
aristotll

Reputation: 9177

I think you redeclare Base and makes the create_all method does not create the table you want to.

The Base in following code is unnecessary.

Base = declarative_base()
Session = sessionmaker()
engine = create_engine('sqlite:///:memory:', echo=True)

Just remove the second Base = declarative_base()

Upvotes: 1

dugup
dugup

Reputation: 426

You need to use the same Base you used when declaring your User table to create the tables in the Base.create_all() method. In your current code you are creating a new declarative base object that doesn't have access to the User model. Make Base a global variable that is the base for the User class and the object you run create_all with

Upvotes: 1

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