How to serialize/deserialize partial JSON object using GSON?

Question

I have very complex JSON with many nested fields coming from backend, example,

{
   "a": ...
   "b": ...
   "not-required-1":{
       "not-required-2":[
           ...
       ]
       ..
   },
   "not-required-3":{
       "not-required-4":[
           ...
       ]
       ...
   }
}

I am only interested in "a" and "b" and I can map to corresponding types for the values. But object has many fields which I don't need but they should serialize when I make changes in "a" and "b".

If I only create type with "a" and "b", when I serialize my object, all "not-required" fields are gone. The only option is to map every field in not-required to corresponding Java class, but they fall in number of 100s.

Clarification,

Backend sends JSON, which is processed in my code and I need to send JSON back to backend.. though I don't need to process all the fields, doesn't mean backend doesn't need them.

I want to convert incoming JSON to POJO and use it through out the app, and serialize it back to JSON using GSON.

C#'s JSON.NET library has support for hybird object serialization using Json.Linq.

c# example.

 class DataObject{

      [JsonProperty("a")]
      DataA A {get;set;}

      [JsonProperty("b")]
      DataB B {get;set;}

      [JsonProperty("not-required-a")]
      Json.Linq.JsonElement NotRequiredA {get;set;}

      [JsonProperty("not-required-b")]
      Json.Linq.JsonElement NotRequiredB; {get;set;}

 }

In C# this way I don't need to map fields of NotRequiredA and NotRequiredB, but they will serialize correctly when needed.

Answer 1

You can use JsonElement. For example:

 class DataObject{

        @Expose @Serialize("a")
        DataA A;


        @Expose @Serialize("b")
        DataB B;

        @Expose @Serialize("not-required-a")
        JsonElement NotRequired;

        ...

 }