Question

I have an internal requirement with nested domain classes where I want updates to a parent relationship to be propagated to children. A code example may make it clear:

class Milestone {
    static belongsTo = [project:Project]
    static hasMany = [goals:OrgGoals, children:Milestone]
    String name
    Date start
    Date estimatedEnd
    Date achievedEnd
    ...
}

When the parent milestone’s estimatedEnd is updated, I want the children’s estimated to automatically be updated by the same amount. GORM’s beforeUpdate() hook seems like a logical place to do this:

To make life easier, I’d like to use some simple Date arithmetic, so I’ve added the following method to the Milestone class:

def beforeUpdate()
    {
        // check if an actual change has been made and the estimated end has been changed
        if(this.isDirty() && this.getDirtyPropertyNames().contains("estimatedEnd"))
        {
            updateChildEstimates(this.estimatedEnd,this.getPersistentValue("estimatedEnd"))
        }
    }

private void updateChildEstimates(Date newEstimate, Date original)
    {
        def difference = newEstimate - original
        if(difference > 0)
        {
            children.each{ it.estimatedEnd+= difference }
        }
    }

No compilation errors. But when I run the following integration test:

void testCascadingUpdate() {
        def milestone1 = new Milestone(name:'test Parent milestone',
            estimatedEnd: new Date()+ 10,
        )
        def milestone2 = new Milestone(name:'test child milestone',
            estimatedEnd: new Date()+ 20,
        )
        milestone1.addToChildren(milestone2)
        milestone1.save()
        milestone1.estimatedEnd += 10
        milestone1.save()
        assert milestone1.estimatedEnd != milestone2.estimatedEnd
        assert milestone2.estimatedEnd == (milestone1.estimatedEnd + 10)
    }

I get:

Unit Test Results.

    Designed for use with JUnit and Ant.
All Failures
Class   Name    Status  Type    Time(s)
MilestoneIntegrationTests   testCascadingUpdate Failure Assertion failed: assert milestone2.estimatedEnd == (milestone1.estimatedEnd + 10) | | | | | | | | | | | Mon Jun 06 22:11:19 MST 2011 | | | | Fri May 27 22:11:19 MST 2011 | | | test Parent milestone | | false | Fri May 27 22:11:19 MST 2011 test child milestone

junit.framework.AssertionFailedError: Assertion failed: 

assert milestone2.estimatedEnd == (milestone1.estimatedEnd + 10)
       |          |            |   |          |            |

       |          |            |   |          |            Mon Jun 06 22:11:19 MST 2011
       |          |            |   |          Fri May 27 22:11:19 MST 2011
       |          |            |   test Parent milestone

       |          |            false
       |          Fri May 27 22:11:19 MST 2011
       test child milestone

    at testCascadingUpdate(MilestoneIntegrationTests.groovy:43)

    0.295

Which suggests that the beforeUpdate is not firing and doing what I want. Any ideas?

Answer 1

I have a solution for you.

1) Call save(flush:true) on your second save call after you update milestone1’s estimatedEnd. This will force beforeUpdate() to fire immediately.

2) Even after you do #1, your assertion will continue to fail because you are comparing 2 slightly different dates (you use a separate Date object within each Milestone constructor, so the 2nd date is slightly later/greater than the first.) If you used the same date instance, e.g.

Date date = new Date() 
def milestone1 = new Milestone(name:'test Parent milestone',
            estimatedEnd: date + 10)
def milestone2 = new Milestone(name:'test child milestone',
            estimatedEnd: date + 20,
        )

then the assertion will be successful. I will leave to you what to do next in terms of the best way to compare slightly different dates, but you might have to tolerate a precision difference on the order of milliseconds.

Hope that helps,

Jordan