Gson remove unnecessary nested object fields

Question

I am trying to serialize an object. I have the following structure:

Class A{
String aField1;
String aField2;
B bObj;
}
Class B{
String bField1;
String bField2;
String bField3;    
}

I am trying to serialze class A and B objects to send them to server. When I am serializing Class A object, it gives me

{
 aField1: "abc",
 aField2: "def",
 B: {
    bField1: "mnp",
    bField2: "qrt",
    bField3: "xyz",
    }
}

And serializing Class B obj:

{
 bField1: "mnp",
 bField2: "qrt",
 bField3: "xyz",
}

But I want Class A object like this:

{
 aField1: "abc",
 aField2: "def",
 B: {
    bField1: "mnp"
    }
}

I am currently using GSON library to accomplish this. I want to remove extra key value pairs when interacting with server. How can I do this?

Use the `@Expose` annotation https://github.com/google/gson/blob/master/UserGuide.md#TOC-Gson-s-Expose to choose exactly which fields are serialised — Ken Wolf, May 31 '16 at 12:57
Using exclusion strategy is the solution to this problem. http://stackoverflow.com/a/4803346/2920114 — Abhishek Lodha, Jun 01 '16 at 09:01

Zahidul Islam · Answer 1 · 2016-05-31T13:02:15.713

0

Change your Serialize class like this way.

public class A implements Serializable{
    String aField1;
    String aField2;
    B bObj;

    class B{
        String bField1;
        String bField2;
        String bField3;
    }
}

Just remove the extra fields. It will not make any problem.

edited May 31 '16 at 13:02

answered May 31 '16 at 12:54

Zahidul Islam

3,180
1
25
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I need those fields. – Abhishek Lodha May 31 '16 at 12:59
I want to make json object for Class A and for Class B also. while making json object for class B, I need all the fields but while making json for Class A, I need some specific field of Class B to be included. – Abhishek Lodha Jun 01 '16 at 06:05

LittleLittleQ · Answer 2 · 2017-11-21T14:15:45.443

0

You can mark bField2 and bField3 as transient or use the annotation @Expose(serialize = false).

Or you can customize your serialization exclusion strategy.
Sample code:

GsonBuilder builder = new GsonBuilder();
Type type = new TypeToken <A>(){}.getType();
builder.addSerializationExclusionStrategy(
        new ExclusionStrategy() {
            @Override
            public boolean shouldSkipField(FieldAttributes fieldAttributes) {
                return fieldAttributes.getName().equals("bField2") ||
                            fieldAttributes.getName().equals("bField3");
            }
            @Override
            public boolean shouldSkipClass(Class<?> aClass) {
                return false;
            }
        }
);

edited Nov 21 '17 at 14:15

answered Apr 12 '17 at 09:12

LittleLittleQ

440
3
7
21

`Type type = new TypeToken (){}.getType();` is not required and this: equals("bField3") --> `)` <--; a syntax error - by fixing that the code block works – emecas Nov 20 '17 at 20:57
No problem :), what about the second line `Type`, is there any reason to keep it ? – emecas Nov 21 '17 at 17:06
@emecas, actually, `builder.create().fromJson(reader, type)` will return the deserialized object – LittleLittleQ Nov 29 '17 at 09:17

Gson remove unnecessary nested object fields

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