Looking at the mysql docs, we can see that there are a bunch of reasons why this error can occur. However, the two main reasons I’ve seen are: 1) The most common reason is that the connection has been dropped because it hasn’t been used in more than 8 hours (default setting) By default, the … Read more
As of version 0.8, SQLAlchemy can resolve the ambiguous join using only the foreign_keys keyword parameter to relationship. publish_user = relationship(User, foreign_keys=[publishing_user_id], backref=backref(‘pages’, order_by=id)) edit_user = relationship(User, foreign_keys=[last_edit_user_id]) Documentation at http://docs.sqlalchemy.org/en/rel_0_9/orm/join_conditions.html#handling-multiple-join-paths
Try this: post = db.session.query(Post).get(1) post.tags = [] db.session.commit() Here we are redefining the collection post.tags to the empty array and committing the changes. To explain this I’ll refer to the SQLAlchemy docs: Collections in SQLAlchemy are transparently instrumented. Instrumentation means that normal operations on the collection are tracked and result in changes being written … Read more
columns have name and type attributes for c in columns: print c.name, c.type
I had this exact same issue – I don’t know if it still affects you. For me, the problem was caused because the schema I was using was not the default – I think the same thing is happening for you, since you’re using a “Products” schema. I posted an issue at: https://bitbucket.org/zzzeek/alembic/issue/281/autogenerate-fails-to-detect-existing And with … Read more
Instead of using filter_by I would recommend using filter, it gives you a lot more options. For example (from the manual): db.session.query(MyClass).filter( MyClass.name == ‘some name’, MyClass.id > 5, ) In relation to your case: filters = ( Transaction.amount > 10, Transaction.amount < 100, ) db.session.query(Transaction).filter(*filters)
You don’t need to import cx_Oracle anymore. The newer version of the sqlalchemy module calls the function cx_Oracle.makedsn(). Have a look: from sqlalchemy.engine import create_engine DIALECT = ‘oracle’ SQL_DRIVER = ‘cx_oracle’ USERNAME = ‘your_username’ #enter your username PASSWORD = ‘your_password’ #enter your password HOST = ‘subdomain.domain.tld’ #enter the oracle db host url PORT = 1521 … Read more
You can use following constructs to filter the Date column using either year or month: .filter(extract(‘year’, Foo.Date) == 2012) .filter(extract(‘month’, Foo.Date) == 12) And group_by is also possible: .group_by(sqlalchemy.func.year(Foo.Date), sqlalchemy.func.month(Foo.Date)) Now I haven’t tested it, but I assume that this might be slow because these queries result in full table scans, therefore I suggest you … Read more
Use the LargeBinary type, which will use the bytea type on PostgreSQL. You can also use the BYTEA type directly if you’re only going to use PostgreSQL. There are other SQL standard types, such as BINARY, but it’s typically easier to use LargeBinary since SQLAlchemy will use the preferred type for each database.
alembic revision –autogenerate inspects the state of the connected database and the state of the target metadata and then creates a migration that brings the database in line with metadata. If you are introducing alembic/sqlalchemy to an existing database, and you want a migration file that given an empty, fresh database would reproduce the current … Read more