OfflineSQLiteOpenHelper.java

/*
 * Copyright (c) 2015-present, Parse, LLC.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */
package com.parse;

import com.tylersuehr.sql.SQLiteDatabase;

/**
 * This class just wraps a SQLiteDatabase with a better API. SQLite has a few limitations that this
 * class works around. The primary problem is that if you call getWritableDatabase from multiple
 * places, they all return the same instance, so you can't call "close" until you are done with all
 * of them. SQLite also doesn't allow multiple transactions at the same time. We don't need
 * transactions yet, but when we do, they will be part of this class. For convenience, this class
 * also wraps database methods with methods that run them on a background thread and return a task.
 */
class OfflineSQLiteOpenHelper extends ParseSQLiteOpenHelper {

    /**
     * The table that stores all ParseObjects.
     */
    /* package */ static final String TABLE_OBJECTS = "ParseObjects";

    /**
     * Various keys in the table of ParseObjects.
     */
    /* package */ /* package */ static final String KEY_UUID = "uuid";
    /* package */ static final String KEY_CLASS_NAME = "className";
    /* package */ static final String KEY_OBJECT_ID = "objectId";
    /* package */ static final String KEY_JSON = "json";
    /* package */ static final String KEY_IS_DELETING_EVENTUALLY = "isDeletingEventually";

    /**
     * The table that stores all Dependencies.
     */
    /* package */ static final String TABLE_DEPENDENCIES = "Dependencies";

    /**
     * Various keys in the table of Dependencies.
     */
    //TODO (grantland): rename this since we use UUIDs as keys now. root_uuid?
    /* package */ static final String KEY_KEY = "key";
    // static final String KEY_UUID = "uuid";

    /**
     * The SQLite Database name.
     */
    private static final String DATABASE_NAME = "ParseOfflineStore";
    private static final int DATABASE_VERSION = 4;

    /**
     * Creates a new helper for the database.
     */
    public OfflineSQLiteOpenHelper() {
        super(DATABASE_NAME, DATABASE_VERSION);
    }

    /**
     * Initializes the schema for the database.
     */
    private void createSchema(SQLiteDatabase db) {
        String sql;

        sql = "CREATE TABLE " + TABLE_OBJECTS + " (" +
                KEY_UUID + " TEXT PRIMARY KEY, " +
                KEY_CLASS_NAME + " TEXT NOT NULL, " +
                KEY_OBJECT_ID + " TEXT, " +
                KEY_JSON + " TEXT, " +
                KEY_IS_DELETING_EVENTUALLY + " INTEGER DEFAULT 0, " +
                "UNIQUE(" + KEY_CLASS_NAME + ", " + KEY_OBJECT_ID + ")" +
                ");";
        db.execSQL(sql);

        sql = "CREATE TABLE " + TABLE_DEPENDENCIES + " (" +
                KEY_KEY + " TEXT NOT NULL, " +
                KEY_UUID + " TEXT NOT NULL, " +
                "PRIMARY KEY(" + KEY_KEY + ", " + KEY_UUID + ")" +
                ");";
        db.execSQL(sql);
    }

    /**
     * Called when the database is first created.
     */
    @Override
    public void onCreate(SQLiteDatabase db) {
        createSchema(db);
    }

    /**
     * Called when the version number in code doesn't match the one on disk.
     */
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // do nothing
    }

    /**
     * Drops all tables and then recreates the schema.
     */
    public void clearDatabase() {
        deleteDatabase(DATABASE_NAME);
    }
}