Persist on SQLite

There are many ORM or ORM-light libraries. But i want a really simple method to work with SQLite. To work with SQLite means you need to define the database and methods, grouped by DAO to work with bean types supported.

Kripton persistence libray allows to manage persistence on SQLite database implementing Dao pattern. As state in definition of DAO pattern, there are:

• a Data Access Object interface: This interface defines the standard operations to be performed on a model object(s).
• a Model Object: is a simple POJO containing get/set methods to store data retrieved using DAO class.
• a Data Access Object implementation: this contains all boilerplate code that Kripton annotation processor will generate for us.

Kripton initialization

Once done Kripton Library setup, before use Kripton to persit on SQLite database, an Android app have to initialize Kripton library. To do this, just add the initialization code in the onCreate method of used Application class.

// set context for Kripton Library
KriptonLibrary.init(this);

Just remember to check if application class is correctly inserted into manifest file.

Usage

The bean to persist with SQLite database is defined in this manner:

@BindTable
public class User  {
  public long id;
  public String email;
  public String name;
  public String surname;
  public String username;
}

It is also possible use @BindType instead of @BindTable.

The SQLite data source definition is done with a simple interface:

@BindDataSource(fileName = "security.db" , daoSet={DaoUser.class})
public interface SecurityDataSource {

}

In the datasource definition there is a DAO definition named DaoUser. This DAO have to define methods to do CRUD operations: read, write, insert and update a bean in the SQLite database.

@BindDao(User.class)
public interface DaoUser {
  @BindSqlInsert
  public long insert(User bean);
	
  @BindSqlUpdate
  public long update(User bean);
	
  @BindSqlDelete(where="id=${id}")
  public long delete(long id);
	
  @BindSqlSelect(where="id=${id}")
  public User selectById(long id);
	
  @BindSqlSelect(where =" name=${name}")
  public List<User> selectById(String name);
}

Primary key

Kripton requires that every database table has a primary key. For performance reason, table's id have to be of type long.

It's possible to define a primary key for a table in differente ways:

• define in the associated bean a long or Long field named id.
• define in the associated bean a long or Long field annotated with @BindColumn(columnType=ColumnType.PRIMARY_KEY)

Usage

Given DaoUser DAO and SecurityDataSource interfaces, Kripton Annotation Processor will generate for us DaoUsercodeImpl and BindSecurityDataSource to work with SQLite database. In this way, after run annotation processor to generate classes associated to data source and dao, to work with database we will use this code:

...
// automatically open and close database connection
try (BindSecurityDataSource dataSource=BindSecurityDataSource.open()) {
  final User user=new User();

  dataSource.getDaoUser().insert(user);		
}

Or, if you need to work with transaction:

final User user=new User();
...
BindSecurityDataSource dataSource=BindSecurityDataSource.instance();		
dataSource.execute(new Transaction() {			
  @Override
  public TransactionResult onExecute(BindSecurityDaoFactory daoFactory) {
    daoFactory.getDaoUser().insert(user);
    return TransactionResult.COMMIT;
  }			 
});

Or, if use Java 8 source code level

final User user=new User();
...
BindSecurityDataSource dataSource=BindSecurityDataSource.instance();		
dataSource.execute(daoFactory -> {
    daoFactory.getDaoUser().insert(user);
    return TransactionResult.COMMIT;
  }			 
});

You can also use batch mode, that is similar to transaction mode, with the difference that batch mode does not use transaction to do operation, simply the operations grouped share same connection.

final User user=new User();
...
BindSecurityDataSource dataSource=BindSecurityDataSource.instance();		
dataSource.executeBatch(daoFactory -> {
    daoFactory.getDaoUser().insert(user);
    return null;
  }			 
});