最后，我创建了遍历JSON对象并创建域实例的代码。

I have a model with 3 classes, A, Parent and Child. A hasMany Parent, and Child extends Parent.

I need to handle complex logic on the UI to create the model, and decided to POST a JSON object with the same structure of my domain model. Now, I have an instance of A that has some instances of Child associated, that in a javascript object on the client side.

When I POST the javascript object, serializing it to a JSON string, the controller receives it ok, then I do: def a = new A(request.JSON);

The A instance is created, but on the hasMany relationship it has instances of Parent instead of instances of Child, so I lose all the attribute values from Child.

How can I tell Grails to create instances of Child instead of instances of Parent?

UPDATE

The request.JSON structure received by the controller looks like this:

[
 name: name,
 group: none,
 where: [
    [
        codeOperand: in_list,
        archetypeId: openEHR-EHR-EVALUATION.problem_diagnosis.v1,
        codeValues: [
            aaa,
            bbb
        ],
        path: /data[at0001]/items[at0005]/value,
        class: Child1,
        terminologyIdValues: [
            cie
        ],
        rmTypeName: DV_CODED_TEXT,
        terminologyIdOperand: eq
    ],
    [
        magnitudeValues: [
            1,
            22
        ],
        archetypeId: openEHR-EHR-OBSERVATION.blood_pressure.v1,
        path: /data[at0001]/events[at0006]/data[at0003]/items[at0004]/value,
        unitsOperand: eq,
        class: Child2,
        magnitudeOperand: between,
        rmTypeName: DV_QUANTITY,
        unitsValues: [
            mmHg
        ]
    ]
 ]
]

On this case I have 2 classes Child1 and Child2 that inherits from Parent.

I've added the "class" attribute to the objects because I read that might solve the problem but it didn't.

When I print the objects associated to the A instance, I got the right number of instances, but all the classes are "Parent", as you can see, some values are binded, but are all attributes of the Parent class.

[
 (archetypeId: openEHR-EHR-EVALUATION.problem_diagnosis.v1,
  path: /data[at0001]/items[at0005]/value,
  rmTypeName: DV_CODED_TEXT,
  class: Parent),
 (archetypeId: openEHR-EHR-OBSERVATION.blood_pressure.v1,
  path: /data[at0001]/events[at0006]/data[at0003]/items[at0004]/value, 
  rmTypeName: DV_QUANTITY,
  class: Parent)
]

I ended up by creating code that traverses the JSON object and creates domain instances.