org.tynamo.jpa.internal
Class JPAGridDataSource<E>

java.lang.Object
  org.tynamo.jpa.internal.JPAGridDataSource<E>

Type Parameters:

E -

All Implemented Interfaces:

org.apache.tapestry5.grid.GridDataSource

public class JPAGridDataSource<E>
extends Object
implements org.apache.tapestry5.grid.GridDataSource

A simple implementation of GridDataSource based on a Hibernate Session and a known entity class. This implementation does support multiple sort constraints; however it assumes a direct mapping from sort constraint property to Hibernate property.

This class is not thread-safe; it maintains internal state.

Typically, an instance of this object is created fresh as needed (that is, it is not stored between requests).

Field Summary

protected javax.persistence.EntityManager

entityManager

Constructor Summary

JPAGridDataSource(javax.persistence.EntityManager em, Class<E> entityType)

Method Summary

protected javax.persistence.criteria.Expression<Boolean>	additionalConstraints(javax.persistence.criteria.CriteriaBuilder cb, javax.persistence.criteria.Root<E> root) Invoked after the main criteria has been set up (firstResult, maxResults and any sort contraints).
int	getAvailableRows() Returns the total number of rows for the configured entity type.
Class	getRowType() Returns the entity type, as provided via the constructor.
Object	getRowValue(int index) Returns a row value at the given index (which must be within the range defined by the call to prepare(int, int, java.util.List) ).
void	prepare(int startIndex, int endIndex, List<org.apache.tapestry5.grid.SortConstraint> sortConstraints) Prepares the results, performing a query (applying the sort results, and the provided start and end index).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

entityManager

protected final javax.persistence.EntityManager entityManager

Constructor Detail

JPAGridDataSource

public JPAGridDataSource(javax.persistence.EntityManager em,
                         Class<E> entityType)

Method Detail

getAvailableRows

public int getAvailableRows()

Returns the total number of rows for the configured entity type.

Specified by:

getAvailableRows in interface org.apache.tapestry5.grid.GridDataSource

prepare

public void prepare(int startIndex,
                    int endIndex,
                    List<org.apache.tapestry5.grid.SortConstraint> sortConstraints)

Prepares the results, performing a query (applying the sort results, and the provided start and end index). The results can later be obtained from getRowValue(int) .

Specified by:

prepare in interface org.apache.tapestry5.grid.GridDataSource

Parameters:

startIndex - index, from zero, of the first item to be retrieved

endIndex - index, from zero, of the last item to be retrieved

sortConstraints - zero or more constraints used to set the order of the returned values

additionalConstraints

protected javax.persistence.criteria.Expression<Boolean> additionalConstraints(javax.persistence.criteria.CriteriaBuilder cb,
                                                                               javax.persistence.criteria.Root<E> root)

Invoked after the main criteria has been set up (firstResult, maxResults and any sort contraints). This gives subclasses a chance to apply additional constraints before the list of results is obtained from the criteria. This implementation does nothing and may be overridden.

getRowValue

public Object getRowValue(int index)

Returns a row value at the given index (which must be within the range defined by the call to prepare(int, int, java.util.List) ).

Specified by:

getRowValue in interface org.apache.tapestry5.grid.GridDataSource

Parameters:

index - of object

Returns:

object at that index

getRowType

public Class getRowType()

Returns the entity type, as provided via the constructor.

Specified by:

getRowType in interface org.apache.tapestry5.grid.GridDataSource