com.datastax.oss.driver.api.mapper.annotations

Annotation Type DaoFactory

@Target(value=METHOD)
 @Retention(value=RUNTIME)
public @interface DaoFactory

Annotates a DAO-producing method in a Mapper interface.

Example:

 @Mapper
 public interface InventoryMapper {
   @DaoFactory
   ProductDao productDao();
 }
 

The return type of the method must be a Dao-annotated interface.

If the method takes no arguments, the DAO operates on the session's default keyspace (assuming that one was set), and the entity's default table:

 // Example 1: the session has a default keyspace
 CqlSession session = CqlSession.builder().withKeyspace("test").build();
 InventoryMapper inventoryMapper = new InventoryMapperBuilder(session).build();
 ProductDao dao = inventoryMapper.productDao();
 Product product = dao.selectById(1);
 // => success (selects from test.product)

 // Example 2: the session has no default keyspace
 CqlSession session = CqlSession.builder().build();
 InventoryMapper inventoryMapper = new InventoryMapperBuilder(session).build();
 ProductDao dao = inventoryMapper.productDao();
 Product product = dao.selectById(1);
 // => CQL error (No keyspace has been specified. USE a keyspace, or explicitly specify keyspace.tablename)
 

You can also have the method take the keyspace and table as arguments (annotated respectively with DaoKeyspace and DaoTable):

 @Mapper
 public interface InventoryMapper {
   @DaoFactory
   ProductDao productDao(@DaoKeyspace String keyspace);

   @DaoFactory
   ProductDao productDao(@DaoKeyspace String keyspace, @DaoTable String table);
 }
 

This allows you to reuse the same DAO interface to operate on different tables:

 ProductDao dao1 = inventoryMapper.productDao("keyspace1");
 Product product = dao1.selectById(1); // selects from keyspace1.product

 ProductDao dao2 = inventoryMapper.productDao("keyspace2");
 Product product = dao2.selectById(1); // selects from keyspace2.product

 ProductDao dao3 = inventoryMapper.productDao("keyspace3", "table3");
 Product product = dao3.selectById(1); // selects from keyspace3.table3
 

In all cases, DAO instances are initialized lazily and cached for future calls:

 ProductDao dao1 = inventoryMapper.productDao("keyspace1", "product");
 ProductDao dao2 = inventoryMapper.productDao("keyspace1", "product");
 assert dao1 == dao2; // same arguments, same instance
 

Note that the cache is a simple map with no eviction mechanism.