Question

I have the following scenario,

Domain class A which hasMany B's
Domain class B which hasMany C's and belongsTo A
Domain class C which belongsTo B

Class E {
 A a
 B b
 C c

 }
 Class C {
  String name
 }

I want to query E values i.e get a list of some E property eg in this case c.name based on values selected by a user in a select box, i.e user selects A and B from multiple select boxes and based on this criteria, a list of names is obtained.

in other words i want to find all names in c which satisfy condition set by a and b

have tried to figure out the GORM query to no avail.

thanks

Answer 1

I solved this by using raw SQL joins. Not really certain if this was the best way but it worked for me.
I got the parameters from A and B, ie

def fromA = params.someCriteriaValueInA
def fromB = params.someCriteriaValueInB

Please note that these are fetched from a gsp. Also, fromB values would be loaded based on fromA values, using chained selects.

In the grails controller/service …

def db = new Sql(dataSource)
def result = db.rows("your sql to go here")

Then you can do whatever you want with the results, for example manipulate it in a template

render(template: "myResults", model:[result :result])

Dont forget to inject the dataSource bean in your controller/service, and also doing the necessary import

import groovy.sql.Sql

Please note that this involved traversing many domain class instances, and for those who like raw SQL this would seem easier.Would appreciate a different approach, maybe using GORM’s criteria.