Gson Serialize field only if not null or not empty

by

Create your own TypeAdapter

public class MyTypeAdapter extends TypeAdapter<TestObject>() {

    @Override
    public void write(JsonWriter out, TestObject value) throws IOException {
        out.beginObject();
        if (!Strings.isNullOrEmpty(value.test1)) {
            out.name("test1");
            out.value(value.test1);
        }

        if (!Strings.isNullOrEmpty(value.test2)) {
            out.name("test2");
            out.value(value.test1);
        }
        /* similar check for otherObject */         
        out.endObject();    
    }

    @Override
    public TestObject read(JsonReader in) throws IOException {
        // do something similar, but the other way around
    }
}

You can then register it with Gson.

Gson gson = new GsonBuilder().registerTypeAdapter(TestObject.class, new MyTypeAdapter()).create();
TestObject obj = new TestObject();
obj.test1 = "test1";
obj.test2 = "";
System.out.println(gson.toJson(obj));

produces 

 {"test1":"test1"}

The GsonBuilder class has a bunch of methods to create your own serialization/deserialization strategies, register type adapters, and set other parameters.

Strings is a Guava class. You can do your own check if you don’t want that dependency.

More Related Contents:

  1. Gson: How to exclude specific fields from Serialization without annotations
  2. Gson serialize a list of polymorphic objects
  3. Trouble with Gson serializing an ArrayList of POJO’s
  4. How do I implement TypeAdapterFactory in Gson?
  5. How do I use Google’s Gson API to deserialize JSON properly?
  6. How to keep fields sequence in Gson serialization
  7. GSON: how to prevent StackOverflowError while keeping circular references?
  8. How to serialize Optional classes with Gson?
  9. Parsing a complex Json Object using GSON in Java
  10. GSON does not deserialize reference to outer class
  11. Convert a JSON string to object in Java ME?
  12. JAVA – Best approach to parse huge (extra large) JSON file
  13. How to Parse JSON Array with Gson
  14. gson throws MalformedJsonException
  15. How to parse JSON Array (Not Json Object) in Android
  16. Parse JSON file using GSON
  17. Jackson: How to add custom property to the JSON without modifying the POJO
  18. Gson and deserializing an array of objects with arrays in it
  19. gson.toJson() throws StackOverflowError
  20. Jackson – How to process (deserialize) nested JSON?
  21. Make GSON accept single objects where it expects arrays
  22. how to parse a huge JSON file without loading it in memory
  23. Can you avoid Gson converting “” into unicode escape sequences?
  24. Gson turn an array of data objects into json – Android
  25. Using a generic type with Gson
  26. Using Gson with Interface Types
  27. How can I prevent gson from converting integers to doubles
  28. Jackson Serialize Instant to Nanosecond Issue
  29. How to serialize a class with an interface?
  30. Jackson deserialize based on type

Leave a Comment