On Thu, May 2, 2013 at 11:43 PM, Paradox <[email protected]> wrote:
> I am trying to ensure that my table doesn't allow duplicate rows.
>
> The table is defined (in SqlAlchemy 0.8):
>
> class User(Base):
> __tablename__ = 'user'
>
> id = Column(Integer, primary_key=True)
> lname = Column(String)
> fname = Column(String)
> email = Column(String)
> dateentered = Column(DateTime, default=datetime.now())
>
> UniqueConstraint('lname','fname',name='full_name')
>
> ~~~~~ etc. ~~~~
>
> I have tried with using the above and with adding the unique constraint
> to the relevant field definitions. Using the unique constraint on
> individual fields makes a table that requires both the lname and the
> fname field to be unique. Using the code above there seems to be no
> constraints whatsoever, a session.commit() simply adds the duplicate
> rows. What I am going for is something like this (using an sqlite3
> database):
>
> CREATE TABLE user (lname string, fname string, email string,
> unique(lname, fname) ON CONFLICT REPLACE);
>
> This will allow me to add multiple rows with the same lname as long as
> the fnames are different for each. Is there a way to define such unique
> constraints in SqlAlchemy?
You need to put your UniqueConstraint in the __table_args__ class
attribute for SQLAlchemy to see it, something like this:
class User(Base):
__tablename__ = 'user'
__table_args__ = (
UniqueConstraint('lname', 'fname', name='full_name'),
)
See the examples at
http://docs.sqlalchemy.org/en/rel_0_8/orm/extensions/declarative.html#table-configuration.
Note that __table_args__ here is a 1-element tuple - the comma on the
end of the line is important.
Hope that helps,
Simon
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