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

Annotation Type GetEntity

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

Annotates a Dao method that converts a core driver data structure into one or more instances of an Entity class.

Example:

 @Dao
 public interface ProductDao {
   @GetEntity
   Product asProduct(Row row);
 }
 

The generated code will retrieve each entity property from the source, such as:

 Product product = new Product();
 product.setId(row.get("id", UUID.class));
 product.setDescription(row.get("description", String.class));
 ...
 

It does not perform a query. Instead, those methods are intended for cases where you already have a query result, and just need the conversion logic.

Parameters

The method must have a single parameter. The following types are allowed:

• GettableByName or one of its subtypes (the most likely candidates are Row and UdtValue).
• ResultSet.
• AsyncResultSet.

The data must match the target entity: the generated code will try to extract every mapped property, and fail if one is missing.

Return type

The method can return:

• a single entity instance. If the argument is a result set type, the generated code will extract the first row and convert it, or return null if the result set is empty.

   @GetEntity
   Product asProduct(Row row);
  
   @GetEntity
   Product firstRowAsProduct(ResultSet resultSet);
         

• a PagingIterable of an entity class. In that case, the type of the parameter must be ResultSet. Each row in the result set will be converted into an entity instance.

   @GetEntity
   PagingIterable<Product> asProducts(ResultSet resultSet);
         

• a MappedAsyncPagingIterable of an entity class. In that case, the type of the parameter must be AsyncResultSet. Each row in the result set will be converted into an entity instance.

   @GetEntity
   MappedAsyncPagingIterable<Product> asProducts(AsyncResultSet resultSet);
         

If the return type doesn't match the parameter type (for example PagingIterable for AsyncResultSet), the mapper processor will issue a compile-time error.