SQLAlchemy with PostgreSQL and Full Text Search

For now I've added the following lines to do it manually, but I'd much rather the 'correct' SQLAlchemy approach if there is one.

create_index = DDL("CREATE INDEX idx_content ON pep USING gin(to_tsvector('english', content));")
event.listen(Pep.__table__, 'after_create', create_index.execute_if(dialect='postgresql'))

There was some interesting discussion on the SQLAlchemy bug tracker. It looks like this is a limitation of the current indexing definition. Basically, my requirement is to allow indexes to be expressions rather than just column names but that isn't currently supported. This ticket is tracking this feature request: http://www.sqlalchemy.org/trac/ticket/695 . However, this is waiting for a developer to take forward and do the work (and has been for a while).

Ran across this old question as I was working on creating some single and multicolumn tsvector GIN indexes. For anyone that is looking for a simple way to create these indexes using string representations of the column names, here is one approach using the SQLAlchemy text() construct.

from sqlalchemy import Column, Index, Integer, String, text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.sql import func


Base = declarative_base()

def to_tsvector_ix(*columns):
    s = " || ' ' || ".join(columns)
    return func.to_tsvector('english', text(s))

class Example(Base):
    __tablename__ = 'examples'

    id = Column(Integer, primary_key=True)
    atext = Column(String)
    btext = Column(String)

    __table_args__ = (
        Index(
            'ix_examples_tsv',
            to_tsvector_ix('atext', 'btext'),
            postgresql_using='gin'
            ),
        )