package io.ebean.config;
/**
* Used to convert between a value object and a known scalar type. The value
* object is the logical type used in your application and the scalar type is
* the value used to persist than to the DB.
* <p>
* The Value object should be immutable and scalar (aka not compound) and
* converts to and from a known scalar type which Ebean will use to persist the
* value.
* </p>
* <p>
* This is an easier alternative to implementing the
* io.ebean.server.type.ScalarType interface.
* </p>
* <p>
* Note that Ebean will automatically try to detect Immutable Scalar Value
* Objects and automatically support them via reflection. This however would not
* be appropriate when the logical type is different from the type you wish to
* use for persistence - for example, if the logical type was long and you
* wanted to use java.sql.Timestamp for persistence. In this case you would want
* to implement this interface rather than let Ebean automatically support that
* type via reflection.
* </p>
*
* @param <B> The value object type.
* @param <S> The scalar object type that is used to persist the value object.
*/
public interface ScalarTypeConverter<B, S> {
/**
* Return the value to represent null. Typically this is actually null but for
* scala.Option and similar type converters this actually returns an instance
* representing "None".
*/
B getNullValue();
/**
* Convert the scalar type value into the value object.
* <p>
* This typically occurs when Ebean reads the value from a resultSet or other
* data source.
* </p>
*
* @param scalarType the value from the data source
*/
B wrapValue(S scalarType);
/**
* Convert the value object into a scalar value that Ebean knows how to
* persist.
* <p>
* This typically occurs when Ebean is persisting the value object to the data
* store.
* </p>
*
* @param beanType the value object
*/
S unwrapValue(B beanType);
}