Interface StatementFactory.ProjectionFunction

Enclosing class:

StatementFactory

public static interface StatementFactory.ProjectionFunction

Strategy interface to compute column projection to be selected for a query based on a given EntityProjection. A projection function can be composed into a higher-order function using otherwise(ProjectionFunction) to form a chain of functions that are tried in sequence until one produces a non-empty Columns object.

Since:

5.0

Author:

Mark Paluch, John Blum, Sam Lightfoot

Method Summary

Modifier and Type	Method	Description
Columns	computeProjection(EntityProjection<?,?> projection, MappingContext<? extends CassandraPersistentEntity<?>, ? extends CassandraPersistentProperty> context)	Compute Columns to be selected for a given EntityProjection.
static StatementFactory.ProjectionFunction	empty()	Empty projection function that returns Columns.empty().
static StatementFactory.ProjectionFunction	mappedProperties()	Projection function that selects mapped properties only.
default StatementFactory.ProjectionFunction	otherwise(StatementFactory.ProjectionFunction fallback)	Compose this projection function with a fallback function that is invoked when this function returns an empty Columns object.
static StatementFactory.ProjectionFunction	primaryKey()	Projection function that selects the primary key.
static StatementFactory.ProjectionFunction	projecting()	Projection function that computes columns to be selected for DTO and closed interface projections.

Method Details

computeProjection

Columns computeProjection(EntityProjection<?,?> projection,
 MappingContext<? extends CassandraPersistentEntity<?>, ? extends CassandraPersistentProperty> context)

Compute Columns to be selected for a given EntityProjection. If the function cannot compute columns it should return an empty Columns object.

Parameters:

projection - the projection to compute columns for.

context - the mapping context.

Returns:

the computed Columns or an empty Columns object.

otherwise

default StatementFactory.ProjectionFunction otherwise(StatementFactory.ProjectionFunction fallback)

Compose this projection function with a fallback function that is invoked when this function returns an empty Columns object.

Parameters:

fallback - the fallback function.

Returns:

the composed ProjectionFunction.

empty

static StatementFactory.ProjectionFunction empty()

Empty projection function that returns Columns.empty().

Returns:

a projection function that returns Columns.empty().

primaryKey

static StatementFactory.ProjectionFunction primaryKey()

Projection function that selects the primary key.

Returns:

a projection function that selects the primary key.

mappedProperties

static StatementFactory.ProjectionFunction mappedProperties()

Projection function that selects mapped properties only.

Returns:

a projection function that selects mapped properties only.

projecting

static StatementFactory.ProjectionFunction projecting()

Projection function that computes columns to be selected for DTO and closed interface projections.

Returns:

a projection function that derives columns from DTO and interface projections.