CODEWITHSUNDEEP
springspring-mvckotlin
Ignazio
Ignazio

Reputation: 4944

Deserialize nested Kotlin object in springMVC

I'm trying to deserialize a complex GET request into a structure of nested objects.

The GET requests looks like:

curl 'localhost:8080/?id=1&inner.id=1'

and the code should look like this:

class RootObj(val id: Int, inner: InnerObject)
class InnerObject(val id: Int)

@RestController
class SearchController {

    @GetMapping(path = ["/"])
    fun getRoot(rootObj: RootObj): String {
        return "ok"
    }
}

This doesn't work out of the box I guess because spring doesn't know how properly create this nested structure.

Parameter specified as non-null is null: [...] parameter inner","path":"/"}%

Is there a way to overcome this problem? Maybe providing a totally custom deserializer code?

As alternative solution, I guess I could flatten the object hierarchy but for doing so I must be able to map a query parameter like inner.id to a field named innerId

Upvotes: 1

Views: 330

Answers (1)

Madhu Bhat
Madhu Bhat

Reputation: 15253

Spring can actually map the query params to the custom object directly, but you need to provide defaults to the params of the custom object constructor.

So you need to define your classes as below for it to work

class RootObj(val id: Int = 0, val inner: InnerObject = InnerObject(0))
class InnerObject(var id: Int = 0)

Do note that the id field of InnerObject would have to be declared as var for Spring to be able to map it. Then curl 'localhost:8080/?id=1&inner.id=1' would work fine.

Upvotes: 2

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