Package org.hibernate.criterion

Source Code of org.hibernate.criterion.AbstractEmptinessExpression

/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008, 2013, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors.  All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA  02110-1301  USA
*/
package org.hibernate.criterion;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.MappingException;
import org.hibernate.QueryException;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.TypedValue;
import org.hibernate.persister.collection.QueryableCollection;
import org.hibernate.persister.entity.Loadable;
import org.hibernate.persister.entity.PropertyMapping;
import org.hibernate.sql.ConditionFragment;
import org.hibernate.type.CollectionType;
import org.hibernate.type.Type;

/**
* Base expression implementation for (not) emptiness checking of collection properties
*
* @author Steve Ebersole
*/
public abstract class AbstractEmptinessExpression implements Criterion {

  private static final TypedValue[] NO_VALUES = new TypedValue[0];

  protected final String propertyName;

  protected AbstractEmptinessExpression(String propertyName) {
    this.propertyName = propertyName;
  }

  /**
   * Should empty rows be excluded?
   *
   * @return {@code true} Indicates the expression should be 'exists'; {@code false} indicates 'not exists'
   */
  protected abstract boolean excludeEmpty();

  @Override
  public final String toSqlString(Criteria criteria, CriteriaQuery criteriaQuery) throws HibernateException {
    final String entityName = criteriaQuery.getEntityName( criteria, propertyName );
    final String actualPropertyName = criteriaQuery.getPropertyName( propertyName );
    final String sqlAlias = criteriaQuery.getSQLAlias( criteria, propertyName );

    final SessionFactoryImplementor factory = criteriaQuery.getFactory();
    final QueryableCollection collectionPersister = getQueryableCollection( entityName, actualPropertyName, factory );

    final String[] collectionKeys = collectionPersister.getKeyColumnNames();
    final String[] ownerKeys = ( (Loadable) factory.getEntityPersister( entityName ) ).getIdentifierColumnNames();

    final String innerSelect = "(select 1 from " + collectionPersister.getTableName() + " where "
        + new ConditionFragment().setTableAlias( sqlAlias ).setCondition( ownerKeys, collectionKeys ).toFragmentString()
        + ")";

    return excludeEmpty()
        ? "exists " + innerSelect
        : "not exists " + innerSelect;
  }


  protected QueryableCollection getQueryableCollection(
      String entityName,
      String propertyName,
      SessionFactoryImplementor factory) throws HibernateException {
    final PropertyMapping ownerMapping = (PropertyMapping) factory.getEntityPersister( entityName );
    final Type type = ownerMapping.toType( propertyName );
    if ( !type.isCollectionType() ) {
      throw new MappingException(
          "Property path [" + entityName + "." + propertyName + "] does not reference a collection"
      );
    }

    final String role = ( (CollectionType) type ).getRole();
    try {
      return (QueryableCollection) factory.getCollectionPersister( role );
    }
    catch ( ClassCastException cce ) {
      throw new QueryException( "collection role is not queryable: " + role );
    }
    catch ( Exception e ) {
      throw new QueryException( "collection role not found: " + role );
    }
  }

  @Override
  public final TypedValue[] getTypedValues(Criteria criteria, CriteriaQuery criteriaQuery)
      throws HibernateException {
    return NO_VALUES;
  }

  @Override
  public final String toString() {
    return propertyName + ( excludeEmpty() ? " is not empty" : " is empty" );
  }
}
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