Grails get child domain objects

Question

I have two domain classes one is parent and other one is child and i have a hasMany relationship between them. Parent class has many childs and child class belongs to parent class. And here is coding example.

class Parent{    String name     static hasMany = [childs:Child]      static constraints = {    } }   class Child{    String name    static belongsTo = [parent:Parent]    static constraints={} } 

Problem is as soon as I get the parent object the child objects associated with parent class were also fetched. But when I convert the object to JSON I don't see the child object completely I can only able to see the ID's of child objects. I want to see all columns of child object instead of only Id.

Converted JSON response:

[{"class":"project.Parent","id":1,   "name":"name1","childs":[{"class":"Child","id":1},{"class":"Review","id":2}]}] 

But I want the response which contains name of child object too, as follows

[{"class":"project.Parent","id":1,"name":"name1",   "childs":[{"class":"Child","id":1,"name":"childname1"},             {"class":"Review","id":2,"name":"childname2"}            ] }] 

Any help greatly appreciated. Thanks in advance.

Answer 1

The issue is with the use of default JSON converter. Here are your options:

 1. Default  -  all fields, shallow associations     a. render blah as JSON   2. Global deep converter - change all JSON converters to use deep association traversal     a. grails.converters.json.default.deep = true   3. Named config marshaller using provided or custom converters     a. JSON.createNamedConfig('deep'){         it.registerObjectMarshaller( new DeepDomainClassMarshaller(...) )     }     b. JSON.use('deep'){         render blah as JSON     }   4. Custom Class specific closure marshaller      a. JSON.registerObjectMarshaller(MyClass){ return map of properties}     b. render myClassInstance as JSON   5. Custom controller based closure to generate a map of properties     a. convert(object){         return map of properties     }     b. render convert(blah) as JSON 

You are currently using Option 1, which is default.

The simplest you can do is use Option 2 to set global deep converter, but be aware this effects ALL domain classes in your app. Which means that if you have a large tree of associations culminating in a top level object and you try to convert a list of those top level objects the deep converter will execute all of the queries to fetch all of the associated objects and their associated objects in turn. - You could load an entire database in one shot :) Be careful.