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.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
boolean	lenient Whether to tolerate missing columns in the source data structure.

Element Detail

lenient

public abstract boolean lenient

Whether to tolerate missing columns in the source data structure.

If false (the default), then the source must contain a matching column for every property in the entity definition, including computed ones. If such a column is not found, an IllegalArgumentException will be thrown.

If true, the mapper will operate on a best-effort basis and attempt to read all entity properties that have a matching column in the source, leaving unmatched properties untouched. Beware that this may result in a partially-populated entity instance.

Default:

false