Get Nested JSON Object with GSON Using Retrofit
Problem Overview:
When consuming an API with JSON responses structured like:
{ 'status': 'OK', 'reason': 'Everything was fine', 'content': { < some data here > }
where the desired POJO data is nested within the "content" field, Retrofit by default deserializes the entire JSON response into a POJO with "status" and "reason" fields, but not the actual data of interest.
Customizing Deserialization:
To extract the nested content field automatically, you can create a custom deserializer using Gson:
Content POJO:
Define a POJO class representing the nested data, such as:
class Content { public int foo; public String bar; }
Deserializer:
Implement a JsonDeserializer
class MyDeserializer implements JsonDeserializer<Content> { @Override public Content deserialize(...) { JsonElement content = je.getAsJsonObject().get("content"); return new Gson().fromJson(content, Content.class); } }
Gson Configuration:
Create a Gson instance with GsonBuilder, registering the custom deserializer:
Gson gson = new GsonBuilder() .registerTypeAdapter(Content.class, new MyDeserializer()) .create();
Enhanced Deserializer for Multiple Types:
If you have multiple types of messages with "content" fields, you can generalize the deserializer as follows:
class MyDeserializer<T> implements JsonDeserializer<T> { @Override public T deserialize(...) { JsonElement content = je.getAsJsonObject().get("content"); return new Gson().fromJson(content, type); } }
Register an instance of this deserializer for each of your content types.
Retrofit Integration:
Pass the customized Gson instance to the Retrofit builder:
Retrofit retrofit = new Retrofit.Builder() .baseUrl(url) .addConverterFactory(GsonConverterFactory.create(gson)) .build();
With this setup, Retrofit will now automatically extract the "content" field and parse it into the appropriate POJO, eliminating the need for manual field extraction.
The above is the detailed content of How Can I Efficiently Extract Nested JSON Data Using Retrofit and Gson?. For more information, please follow other related articles on the PHP Chinese website!