On Aug 21, 2008, at 4:28 PM, Jeff wrote:
>
> Hello. I'm trying to writing something to generate full text searches
> for postgres. Here's the function I've got so far:
>
> from sqlalchemy import sql
> import operator
>
> def full_text(fields, text):
> def alternate(items):
> for i in items[:-1]:
> yield i
> yield sql.text(" ' ' ")
> yield items[-1]
>
> return "%s @@ to_tsquery('%s')" % (
> sql.func.to_tsvector(
> reduce(operator.add, alternate(fields))
> ), text)
>
> You pass it a list of columns to match against and a full-text string
> to search with, and it returns a string that you can use in a filter()
> clause. It works fine if you only pass one or two column names--any
> more than that, and it dies. At first, I thought it was something
> wrong with my generator, but it turns out there's something wrong with
> the way I'm concatenating columns and raw text--that, or there's a bug
> there. Below is a simple example of what goes wrong.
>
> from sqlalchemy import *
>
> table1 = Table('table1', MetaData(),
> Column('col1', String()),
> Column('col2', String()),
> Column('col3', String()),
> )
>
> #these work
> print table1.c.col1 + table1.c.col2 + table1.c.col3
> print table1.c.col1 + text('sdf') + table1.c.col2 + table1.c.col3
> print table1.c.col1 + text('sdf') + table1.c.col2
>
> #these don't
> print table1.c.col1 + table1.c.col2 + text('sdf')
> print table1.c.col1 + table1.c.col2 + table1.c.col3 + text('sdf')
> print table1.c.col1 + text('sdf') + table1.c.col2 + text('sdf')
> print table1.c.col1 + text('sdf') + text('sdf')
>
> The ones that don't work die with "AttributeError: 'NoneType' object
> has no attribute 'adapt_operator'" on line 1328 in sqlachemy/sql/
> expression.py
>
> Is this a bug, or am I doing this wrong? And all that aside, is there
> an existing way to generate a full-text search like that?
in general, text() is intended primarily for fully constructed SQL
statements, and does not implement the semantics of an element used
within an expression. For individual literal components, use the
literal() function which produces a bind parameter, which will have
all the semantic properties of any other column-oriented expression
element. if that doesn't resolve your issue we can try again with
something more concrete.
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