QuestionDeserializer.java

package ca.ualberta.cs.cmput301f14t14.questionapp.model.serializer;

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.UUID;

import android.content.Context;
import android.util.Log;
import ca.ualberta.cs.cmput301f14t14.questionapp.data.DataManager;
import ca.ualberta.cs.cmput301f14t14.questionapp.model.Image;
import ca.ualberta.cs.cmput301f14t14.questionapp.model.LocationHolder;
import ca.ualberta.cs.cmput301f14t14.questionapp.model.Question;

import com.google.gson.JsonArray;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;

/**
 * Class used by GSON to deserialize Question objects
 */
public class QuestionDeserializer implements JsonDeserializer<Question> {
	private DataManager dm;

	public QuestionDeserializer(Context context) {
		dm = DataManager.getInstance(context);
	}

	public Question deserialize(final JsonElement json, final Type type,
			final JsonDeserializationContext context) throws JsonParseException {
		final JsonObject jsonObject = json.getAsJsonObject();

		Question question;
		UUID qid = UUID.fromString(jsonObject.get("id").getAsString());
		
		// Get existing object if available
		try {
			question = dm.getLocalDataStore().getQuestion(qid);
		} catch (IOException e) {
			Log.e("QuestionDeserializer", "Failed to get question record");
			question = null;
		}
		if (question == null)
			question = new Question();
		
		// Populate object
		question.setId(qid);
		question.setTitle(jsonObject.get("title").getAsString());
		question.setBody(jsonObject.get("body").getAsString());
		question.setAuthor(jsonObject.get("author").getAsString());
		question.setDate((Date) context.deserialize(jsonObject.get("date"), Date.class));
		question.setUpvotes(jsonObject.get("upvotes").getAsInt());
		question.setImage((Image) context.deserialize(jsonObject.get("image"), Image.class));
		question.setLocation((LocationHolder) context.deserialize(jsonObject.get("location"), LocationHolder.class));
		
		// Populate comment list
		List<UUID> commentList = new ArrayList<UUID>();
		JsonArray commentJsonArray = jsonObject.getAsJsonArray("comments");
		for (JsonElement cIdElement: commentJsonArray) {
			commentList.add(UUID.fromString(cIdElement.getAsString()));
		}
		question.setCommentList(commentList);
		
		// Populate answer list
		List<UUID> answerList = new ArrayList<UUID>();
		JsonArray answerJsonArray = jsonObject.getAsJsonArray("answers");
		for (JsonElement aIdElement: answerJsonArray) {
			answerList.add(UUID.fromString(aIdElement.getAsString()));
		}
		question.setAnswerList(answerList);
		return question;
	}

}