Has anyone done a gqlquery with a like condition

[atomstore]

Does anyone know how to perform a LIKE condition on a select statement
in gql? I want to search a datastore and filter the query similar to
select * from emp where ename like 'S%' ;? In the normal Django api I
can do this as Person.objects.filter(name__icontains=value) on the
model.

Thanks

[barryhunter]

Have a look at
http://code.google.com/appengine/docs/datastore/queriesandindexes.html
there is a Tip there on how to do that.

But it doesn't help with '%ending' style queries;p

[Cary Palmer]

I tried to execute the query using the method described in the link
provided and I couldn't get it to work. I have this gqlquery gifts =
db.GqlQuery("SELECT * FROM Gift where name >= :1 AND name < :
2","dat", "dat") and its returns no rows. If I drop the second
parameter it returns all rows. COnsidering a like conditions are not
possible my thinking is to filter the resultset with a regular
expression, but that would mean a rather inefficient query if I had a
large resultset. These are my records in the store:

data
major tom
database
holiday

[Benjamin Wohlwend]

Hi,

On Apr 15, 2:51 am, Cary Palmer <palmer.c...@gene.com> wrote:
> I tried to execute the query using the method described in the link  
> provided and I couldn't get it to work.  I have this gqlquery gifts =  
> db.GqlQuery("SELECT * FROM Gift where name >= :1 AND name < :
> 2","dat", "dat") and its returns no rows.

Try something like this:

the_string = 'dat'
gifts = db.GqlQuery('SELECT * FROM Gift WHERE name >= :1 AND name < :
2', the_string, the_string + 'z')

The docs (linked above by barryhunter) recommend to add "\xEF\xBF\xBD"
instead of 'z', because "\xEF\xBF\xBD" is the largest possible unicode
character, but that throws errors here and 'z' seems to work, too.

Regards,

Benjamin

[Cary Palmer]

That worked great. I'm assuming the 'z' set the high order of the range properly. Thanks much!

[Brett Morgan]

Assuming you are searching for 'foo' the query that DataStore executes
looks like this

SELECT * FROM Gift WHERE name >= 'foo' AND name < 'fooz'

[Cary Palmer]

What I'm doing is an autocomplete ajax function that queries the database based on the characters entered on the ui. This worked with mysql and oracle. I want to return say the first five items from the query. I would thiink this query will do the job.

[Brett Morgan]

Give it a try and get back to us with details on how it performs with
your dataset size?

If it doesn't perform, you have the option of building a trie over the
dataset in question:

http://en.wikipedia.org/wiki/Trie