withCriteria two level deep association eager fetch grails

问题

I'd like to eager load a structure, two levels deep in an association chain. Something along the lines of:

class TopLevel {
    String name

    LevelOne levelOne
}    

class LevelOne {
    String name

    LevelTwo levelTwo
}

class LevelTwo {
    String name
}

I'd like to load the entire structure. Searching around I found this example, but it didn't work. The "println" generated a query to the LevelTwo table.

def result = TopLevel.withCriteria {
    eq('name', 'test')
    fetchMode "levelOne", FetchMode.JOIN
    levelOne {
        fetchMode "levelTwo", FetchMode.JOIN
    }
}

println result.levelOne.levelTwo.name

Appreciate any help!
- Steve

回答1:

Got it working. Here's the secret sauce:

def result = TopLevel.withCriteria {
    eq('name', 'test')
    fetchMode 'levelOne', FetchMode.JOIN
    fetchMode 'levelOne.levelTwo', FetchMode.JOIN
    fetchMode 'levelOne.levelTwo.levelThree', FetchMode.JOIN
}

来源：https://stackoverflow.com/questions/4176121/withcriteria-two-level-deep-association-eager-fetch-grails