To add, you’d need: https://alembic.sqlalchemy.org/en/latest/ops.html#alembic.operations.Operations.create_unique_constraint from alembic import op op.create_unique_constraint(‘uq_user_name’, ‘user’, [‘name’], schema=”my_schema”) To drop, you’d need: https://alembic.sqlalchemy.org/en/latest/ops.html#alembic.operations.Operations.drop_constraint op.drop_constraint(‘uq_user_name’, ‘user’, schema=”my_schema”)
For anyone coming here from google 4 years later, func is now in sqlalchemy.sql.expression. Example: from sqlalchemy.sql.expression import func session.query(func.max(Table.column))
from sqlalchemy import * from sqlalchemy.orm import mapper, sessionmaker import os engine = create_engine(‘sqlite://’, echo=True) metadata = MetaData(engine) sample = Table( ‘sample’, metadata, Column(‘id’, Integer, primary_key=True), Column(‘lob’, Binary), ) class Sample(object): def __init__(self, lob): self.lob = lob mapper(Sample, sample) metadata.create_all() session = sessionmaker(engine)() # Creating new object blob = os.urandom(100000) obj = Sample(lob=blob) session.add(obj) session.commit() … Read more
The ORM is, as the name implies, an object-relational mapper: Its purpose is to represent database relations as Python objects. The core is a query builder. Its purpose is to provide a programmatic means to generate SQL queries (and DDL) — but the results of those queries are just tuples (with a little extra magic), … Read more
By the sounds of it, you are more interested in sequentially listed revision files rather than sequentially ordered revision ids. The former can be achieved without any change to how the revision ids are generated. The alembic.ini file that is generated when you run alembic init alembic has a section that configures the naming of … Read more
Take a look at Query.first(). If you specify a sort on the right column, the first will be your last. An example could look like this: obj = session.query(ObjectRes).order_by(ObjectRes.id.desc()).first()
In case columns are declared in the same order as they should be in the primary key: class User(Base): field1 = Column(Integer, primary_key=True) field2 = Column(Integer, primary_key=True) Otherwise declare it in __table_args__: class User(Base): field1 = Column(Integer) field2 = Column(Integer) __table_args__ = ( PrimaryKeyConstraint(field2, field1), {}, )
If using SQLAlchemy version 0.8 or later, you should use the runtime inspection API. If the model class is User and the sole primary key is id, >>> from sqlalchemy.inspection import inspect >>> inspect(User).primary_key[0].name ‘id’ If the model class is User and there are many primary keys, >>> from sqlalchemy.inspection import inspect >>> [key.name for … Read more
You actually want the label method. result = dbsession.query( Shares.price, func.sum(Shares.quantity).label(“Total sold”) ) \ .filter(Shares.company== ‘Google’) \ .group_by(Shares.price).all()
I know this question is specifically about v0.5.8, but for anyone coming here from google 4 years later, func is now in sqlalchemy.sql.expression. Example: from sqlalchemy.sql.expression import func session.query(func.max(Table.column))