batch updates

[Lincoln]

Hey guys, 

Is there any way to send a batch of updates to the same document via the Java driver in a single call?

I have a document with 3 fields I want to update - 1 data field and 2 counters.  I've been trying to create an update DBObject and continue calling add() on it but not only does this not seem to work, I start getting the following exception when I try to call toString on it:

java.lang.RuntimeException: can't serialize type : class java.util.HashMap

        at com.mongodb.util.JSON.serialize(JSON.java:128)

        at com.mongodb.util.JSON.serialize(JSON.java:108)

        at com.mongodb.util.JSON.serialize(JSON.java:32)

        at com.mongodb.BasicDBObject.toString(BasicDBObject.java:192)

Very weird stuff.  Please let me know if I'm just going about this wrong.  If it's not obvious I can send along an illustrative example.

Thanks,

Lincoln

[Eliot Horowitz]

Can you send the code you're using? I think this should work in theory...

[Lincoln]

Hey,

After testing some more it actually seems like it's executing the $set and the last $inc but not the middle $inc.  I guess BasicDBObject is backed by a hash so I'm overwriting the $inc key.  Is there a way to batch multiple $incs?

Here's the (pseudo) code:

import com.mongodb._

import com.mongodb.{BasicDBObject => DBO}

val query = new DBO("_id", user.id.objectId)

val update = new DBO("$set", new DBO("status", user.status))

update.append("$inc", new DBO("stats.total", 1))

update.append("$inc", new DBO("stats.type", 1))

mongo.getCollection("users").update(query, update, true, false)

Also, any thoughts on why calling update.toString throws that exception I mentioned?  That's almost bugging me more than the $inc because it's preventing me from logging my update.

Thanks,

Lincoln

[Dwight Merriman]

Hi,

I think you need to put both of the $inc’s inside a single $inc object.  Here is an example from the mongo shell (I don’t know the java driver well):

~/mongo ./mongo
> t = db.bar
test.bar

> t.save( { name : 'joe' } )

> t.update({}, {$set : { status : 2 }, $inc : { total : 1, type : 1 }} );

> t.findOne()
{"_id" :  ObjectId( "4a8562dff14fa07f46a382d9")  , "name" : "joe" , "status" : 2 , "total" : 1 , "type" : 1}

> t.update({}, {$set : { status : 2 }, $inc : { total : 1, type : 1 }} );

> t.findOne()
{"_id" :  ObjectId( "4a8562dff14fa07f46a382d9")  , "name" : "joe" , "status" : 2 , "total" : 2 , "type" : 2}

[Lincoln]

OK thanks, I'll give that a try.  

[Lincoln]

Awesome, that fixed it.

In the java driver it looks like this:

val update = new DBO("$inc", new DBO("total", 1).append("text", 1))

Thanks,

Lincoln