LiveQueryLoader

LiveQueryLoader.java

package com.meubilhete.model.dao.loader;

import android.content.Context;
import android.os.Handler;
import android.support.v4.content.AsyncTaskLoader;
import android.util.Log;
import com.couchbase.lite.CouchbaseLiteException;
import com.couchbase.lite.LiveQuery;
import com.couchbase.lite.QueryEnumerator;

public abstract class LiveQueryLoader<T> extends AsyncTaskLoader<T> implements LiveQuery.ChangeListener {


    private T object;
    private QueryEnumerator rows;
    private LiveQuery liveQuery;

    private Handler handler;

    public LiveQueryLoader(Context context, LiveQuery liveQuery){
        super(context);
        this.liveQuery = liveQuery;
        this.liveQuery.addChangeListener(this);

        Log.w(this.getClass().getName(), "new()");
    }

    @Override
    protected void onStartLoading() {
        Log.w(this.getClass().getName(), "onStartLoading()");
        if(handler == null){
            handler = new Handler();
        }

        if (object != null) {
            Log.w(this.getClass().getName(), "onStartLoading() - deliverResult()");
            deliverResult(object);
        }

        if (object == null || rows.isStale()) {
            Log.w(this.getClass().getName(), "onStartLoading() - forceLoad()");
            forceLoad();
        }
    }

    @Override
    public T loadInBackground() {
        Log.w(this.getClass().getName(), "loadInBackground()");
        try {
            liveQuery.waitForRows();

            rows = liveQuery.getRows();

            object = loadObjectFromRows(rows);
            return object;
        } catch (CouchbaseLiteException e) {
            throw new RuntimeException(e);
        }
    }

    protected abstract T loadObjectFromRows(QueryEnumerator rows);

    @Override
    public void changed(LiveQuery.ChangeEvent event) {
        Log.w(this.getClass().getName(), "changed()");
        rows = event.getRows();
        object = loadObjectFromRows(rows);
        handler.post(new Runnable() {
            @Override
            public void run() {
                deliverResult(object);
            }
        });
    }

    @Override
    protected void onStopLoading() {
        Log.w(this.getClass().getName(), "onStopLoading()");
        // Attempt to cancel the current load task if possible.
        cancelLoad();
    }

    @Override
    public void onCanceled(T data) {
        Log.w(this.getClass().getName(), "onCanceled()");
        liveQuery.stop();
    }

    @Override
    protected void onReset() {
        Log.w(this.getClass().getName(), "onReset()");
        super.onReset();

        // Ensure the loader is stopped
        onStopLoading();

        liveQuery.removeChangeListener(this);
        liveQuery.stop();
        object = null;
        rows = null;
    }
}