如何创建自定义函数以返回grails条件方法的关闭

Question

I'm trying to abstract this top block of code out to look like the bottom block of code.

if (params.xId) {
    and {
       'in'(aggregateClassReference, hierarchy['x'])
        eq(aggregateIdReference, params.xId as Long)
     }
}
if (params.yId) {
   and {
       'in'(aggregateReference, hierarchy['y'])
        eq(aggregateIdReference, params.yId as Long)
   }
}

...

if (params.xId) { belongsToHierarchy('x', params.xId as Long) }
if (params.yId) { belongsToHierarchy('y', params.yId as Long) }

I'm using gorm criteria queries, but I don't want these big chunks of code. Is there a way to return a closure of these criteria queries in a custom function? The problem right now is I put the below chunks of code in

def criteria = DetachedCriteria.build(...)

Afterwards I do a

criteria.list(...)

to execute. It'd be great to somehow return a closure of just the

 and {
    'in'{...}
    eq {...}
 }

in a custom function within the build, but I haven't been able to figure that out yet. A bit new to grails. Any insight to guide me would be much appreciated :)

Answer 1

There are a number of ways to do about this. You haven't shown enough context to narrow in on exactly the best solution is to what you are doing but given what is there I can show somethings that might help.

If you wanted to use criteria queries then instead of something like this...

def results = SomeDomainClass.withCriteria {
    if (params.xId) {
        and {
            'in'(aggregateClassReference, hierarchy['x'])
            eq(aggregateIdReference, params.xId as Long)
        }
    }
    if (params.yId) {
       and {
           'in'(aggregateReference, hierarchy['y'])
            eq(aggregateIdReference, params.yId as Long)
       }
    }
}

You could do something like this...

def results = SomeDomainClass.withCriteria {
    if (params.xId) {
        belongsToHierarchy 'x', params.long('xId'), delegate
    }
    if (params.yId) {
        belongsToHierarchy 'y', params.long('yId'), delegate
    }
}

// ...

// it isn't clear from your example if
// aggregateClassReference and hierarchy are local
// variables in the context where the criteria
// query is being initialized or if they are
// instance variables.  If they are instance variables
// the code below will work.  If they are local
// variables then they might need to be passed as
// arguments into this belongsToHierarchy method...

void belongsToHierarchy(String arg, long id, delegate) {
    def query = {
        // not sure why you had the "and" in your example, but
        // I will leave it here assuming there is a reason...
        and {
            'in' aggregateClassReference, hierarchy[arg]
            eq aggregateIdReference, id
        }
    }
    query.delegate = delegate
    query()
}