what is the best practice for handle complex object in a restful web services in JAVA

Question

I have a complex class, that have many objects inside, when I do GET, I want to see the full object with all inner objects data, but when I POST, I only want to pass ID's for inner objects.

Example:

class ComplexObject {
    private InnerObject1 innerObject1;
    private InnerObject2 innerObject2;

    //setters and getters
}

when I do GET, I want to retrieve the full JSON, that's the easy part, but when I save the ComplexObject, I want to only pass the id's for the innerObject1 and innerObject2, not the whole object.

How can I achieve that?

You have 2 different endpoints so you can have 2 different DTO or 1 DTO and pass incomplete data in one of them. However, I don't understand your question. Why do you want to send incomplete data in POST? — Justinas Jakavonis, Jan 12 '17 at 09:34
In the post, the inner objects are huge, and they are a separate entities, I only need there ID's to handle the One to Many relation ships — kdureidy, Jan 12 '17 at 09:37
Do you map ComplexObject received from REST call directly to Hibernate entity? — Justinas Jakavonis, Jan 12 '17 at 09:42
What is problem to send to the server a new JSON with only those fields which you need to change? I assume you have a methods toJson and fromJson, so you can do transformation stringId -> ComplexObject.fieldName. Where is a problem? — Michel_T., Jan 12 '17 at 09:54
Who said there is a problem, my question is about the best practice? is it the best practice to use DTO's? Why? — kdureidy, Jan 12 '17 at 09:58
Why do you think it may be bad practice? And what's your alternatives? — Justinas Jakavonis, Jan 12 '17 at 10:48
I don't know, that's why I am asking. I didn't like the idea of having to duplicate your entities by creating DTO's and mappers. — kdureidy, Jan 16 '17 at 10:20

score 1 · Accepted Answer · edited May 23 '17 at 12:24

You shouldn't use Hibernate entities for sending and receiving data in REST calls. Use separate objects for this - data transfer object (DTO) - What is Data Transfer Object?. In your case, it may be ComplexObjectWithIds which contains only ids:

@POST
@Path("/complex-object")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response postComplexObject(ComplexObjectWithIds complexObjectWithIds)

And ComplextObjectFull with full data:

@GET
@Path("/complex-object")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public ComplextObjectFull getComplexObject()

score 0 · Answer 2 · answered Jan 12 '17 at 09:32

When you post the object you can parse the JSON you send and retrieve the needed objects by ID in your controller, and then rebuild the object there and send the full object to be created.

For example, let's say you have an ObjectController, and on the post route you will build a complex JSON.

//Post request to this method
public void addObject(@RequestBody Object obj) {
    Object newObj = new Object(obj);

    //Get the full objects by id
    InnerObject innerObj = innerObjectService.findById(obj.innerObjectId);

    //Build the full new object
    newObj.setInnerObj(innerObj);

    //Create the object
    ...
 }

Yes, it's very similar to DTO's. Actually it's a better practice to use DTO's instead of the base Objects as the other answer pointed out. — Ionut Robert, Jan 13 '17 at 15:22

what is the best practice for handle complex object in a restful web services in JAVA

2 Answers2