Grails: sum of field within criteria builder

I'm at a loss of how to create a running sum of particular field after creating a criteria within a controller

I'm currently creating a set of set of records using:

    def b = Tapes.createCriteria()
    def yesterday =  b.list(sort: 'migratedDate', order: 'asc') {
        between ("migratedDate", dat.minus(1), dat)
    }

and counting the number of items in that set with

def num2 = Tapes.countByMigratedDateBetween(dat.minus(1), dat)

one of the fields in m开发者_如何学JAVAy domain is "migratedDuration", the system is returning the runtime of the process in milliseconds. Is there a way in the controller to create a sum of this number? Or should I have to do this via javascript in the corresponding .gsp file?

Thanks Again,

an awful awful hack

This worked perfectly, thanks

def todayTime = aa.list() { 
    between ("migratedDate", dat.minus(4), dat.minus(3)) 
    projections { sum('migratedDuration') 
    } 
}

You can use a projection for this:

def b = Tapes.createCriteria()
def yesterday = b.list() {
    projections {
        sum('migratedDuration')
    }
}

A list of available Projections can be found here.

Is it truly a 'running sum' i.e. does it increment on each row or do you need the sum across all rows?

A sum across all rows can be done with a Projection (have a read of the doco for the "projections" closure provided by CriteriaBuider).

If it's a running total, you'll need to do that in the controller or view your self as you loop across the rows in the result list.

cheers

Lee