JSON is a text format for exchanging data. It is a subset of the JavaScript Object Notation and is considered a language-independent format. JSON is used to serialize structured data and exchange it across a network. It is easy to read and write, and software can parse and generate it with ease.

The library will store a JSON file for each model. Searching is done using the model's ID to access it directly without loading unnecessary data.

Serialization and deserialization

import com.google.gson.JsonObject;
import es.revengenetwork.storage.codec.ModelDeserializer;
import es.revengenetwork.storage.codec.ModelSerializer;
import es.revengenetwork.storage.gson.codec.JsonReader;
import es.revengenetwork.storage.gson.codec.JsonWriter;
import org.jetbrains.annotations.NotNull;

public final class UserModelCodec {
  private UserModelCodec() {
    throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
  }

	public enum Serializer implements ModelSerializer<UserModel, JsonObject> {
    INSTANCE; // We use lazy singleton to access the instance from anywhere.

    @Override
    public @NotNull JsonObject serialize(final @NotNull UserModel userModel) {
      return JsonWriter.create()
               .writeString("id", userModel.id())
               .writeString("name", userModel.name())
               .writeNumber("age", userModel.age())
               .writeDate("birthday", userModel.birthday())
               .end();
    }
  }

  public enum Deserializer implements ModelDeserializer<UserModel, JsonObject> {
    INSTANCE; // We use lazy singleton to access the instance from anywhere.

		// We suppress it since our data should never be null in this case
		// as we ensure to write them all correctly.
    @SuppressWarnings("DataFlowIssue")
    @Override
    public @NotNull UserModel deserialize(final @NotNull JsonObject serialized) {
      final var reader = JsonReader.create(serialized);
      return new UserModel(
        reader.readString("id"),
        reader.readString("name"),
        reader.readInt("age"),
        reader.readDate("birthday"));
    }
  }
}

Creating repositories

Without caching

final AsyncModelRepository<UserModel> userModelRepository = 
	GsonModelRepository.builder(UserModel.class)
	  .folder(folderPath.resolve("users")) // This will be the folder where the files are saved.
    .prettyPrinting(true) // This is optional, depending on whether you want a pretty format in the file.
    .modelSerializer(UserModelCodec.Serializer.INSTANCE)
    .modelDeserializer(UserModelCodec.Deserializer.INSTANCE)
    .build(executor); // The executor is necessary for async operations.

Caching

final AsyncModelRepository<UserModel> userModelRepository =
	GsonModelRepository.builder(UserModel.class)
	  .folder(folderPath.resolve("users")) // This will be the folder where the files are saved.
    .prettyPrinting(true) // This is optional, depending on whether you want a pretty format in the file.
    .modelSerializer(UserModelCodec.Serializer.INSTANCE)
    .modelDeserializer(UserModelCodec.Deserializer.INSTANCE)
    .buildCached(executor, LocalModelRepository.concurrent() /* This is the repository that will function as a cache. */);

Result

folder/users/someId.json

{
	"id": "someId",
	"name": "Angel Miranda",
	"age": 18,
	"birthday": 1088150036 // It stores only the timestamp of the date.
}