How do we query on an embedded BsonRecord field

[Rohit Rai]

This is a question regarding this User class -

https://github.com/rohit-tingendab/ks-lift/blob/master/src/main/scala/com/tingendab/kslift/model/User.scala

I have profile BsonRecord embedded in User, now during search I want to search the User based on his/her displayName that is part of the the profile.

I have 2 queries in this -

User.findAll("profile.displayName" -> filter)  or User.findAll("profile.is.displayName" -> filter) ?

According to my understanding this will give only an exact match... Hpw can I do an "like" query so that I can give results i the user submits half a name too.

Regards,

Rohit

[Rohit Rai]

Just to confirm, I tried it and this works with exact value match - User.findAll("profile.displayName" -> filter) 

but am still trying to figure out the query to get a match from a partial name (sql like).

[Tim Nelson]

Hi Rohit,

You need to use a regex in your query:

http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-RegularExpressions

Tim

[Rohit Rai]

Hi Tim,
I saw that and can use regex in mongodb... But I am not sure how to build a regex query in json dsl or query builder in lift.

Are there any examples of it?

Regards,
Rohit

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[Tim Nelson]

Hi,

To build a regex query using the json dsl, you need to use the PatternSerializer [1]. Add that to your record's formats and your query would look like:

User.findAll("profile.displayName" -> (("$regex" -> "/regex") ~ ("$flags" -> 0)))

If you want to use the java-mongo-driver directly, I believe you need to use BasicDBObjectBuilder.

You may also be able to use Rogue [2]. See line 121.

Tim

1 - https://github.com/lift/framework/blob/master/persistence/mongodb/src/main/scala/net/liftweb/mongodb/Serializers.scala

2 - https://github.com/eltimn/rogue/blob/master/src/test/scala/com/foursquare/rogue/QueryTest.scala

[Brendan W. McAdams]

Keep in mind as well that Rebecca queries in MongoDB can only hit an index if you anchor to the start of the field (^). The query profiler output can sometimes be misleading on this point but we are unable to use indexes without a start anchor.

If you want to avoid tablescans there are a few tips for approaches on the MongoDB wiki ( http://www.mongodb.org/display/DOCS/Full+Text+Search+in+Mongo).  Native full text search is on the roadmap for sometime this year as well.

On Jun 12, 2011 7:27 AM, "Tim Nelson" <tnel...@gmail.com> wrote:

[Brendan W. McAdams]

That should have read 'regex' queries. Damn autocorrect.

[Antonio Salazar Cardozo]

My personal approach is to do something like:

val regex = """^/hello""".r

User.findAll("profile.displayName" -> decompose(regex))

The downside is it requires that you declare an implicit val (implicit val formats = User.formats is what I do), but I find it reads more naturally. You also have to import net.liftweb.json.Extraction._ to get the decompose function.

Thanks,

Antonio

[Rohit Rai]

Thanks for the replies guys... I have not yet got a chance to try this out... will reply as soon as I am able to work on this part again.

Regards,
Rohit

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