Sqlalchemy: Possible to Declare a Column as Primary Key Declaratively?
I Have a Base Class Mixin: Class Mycolumns(Object): Id = Column(Integer) Foo = Column(Integer) Bar = Column(Integer) Class Mymaintable(Mycolumns, Base)...
I have a base class mixin:
class MyColumns(object):
id = Column(Integer)
foo = Column(Integer)
bar = Column(Integer)
class MyMainTable(MyColumns, Base):
__tablename__ = 'main_table'
pk_id = PrimaryKeyConstraint("id")
I want to be able to declare id as the PK on MyMainTable. I can't declare it as PK within MyColumns, because I need to use MyColumns in another table, where id is NOT the PK (done for auditing purposes). When I run the above code, I get
sqlalchemy.exc.ArgumentError: Mapper Mapper|MyMainTable|main_table could not assemble any primary key columns for mapped table 'main_table'
Is there any way to add the PK declaration this way?
1 Answer
I found the solution as documented here:
You need to add the constraints to __table_args__:
class MyColumns(object):
id = Column(Integer)
foo = Column(Integer)
bar = Column(Integer)
class MyMainTable(MyColumns, Base):
__tablename__ = 'main_table'
__table_args__ = (
PrimaryKeyConstraint("id", name="pk_id"),
)
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