[hibernate-commits] Hibernate SVN: r15275 - core/branches/Branch_3_3/core/src/main/java/org/hibernate/criterion.

Author: steve.ebersole(a)jboss.com Date: 2008-10-08 00:55:29 -0400 (Wed, 08 Oct 2008) New Revision: 15275 Modified: core/branches/Branch_3_3/core/src/main/java/org/hibernate/criterion/Projection.java Log: javadoc Modified: core/branches/Branch_3_3/core/src/main/java/org/hibernate/criterion/Projection.java =================================================================== --- core/branches/Branch_3_3/core/src/main/java/org/hibernate/criterion/Projection.java 2008-10-08 04:55:07 UTC (rev 15274) +++ core/branches/Branch_3_3/core/src/main/java/org/hibernate/criterion/Projection.java 2008-10-08 04:55:29 UTC (rev 15275) @@ -32,73 +32,106 @@ import org.hibernate.type.Type; /** - * An object-oriented representation of a query result set projection - * in a <tt>Criteria</tt> query. Built-in projection types are provided - * by the <tt>Projections</tt> factory class. - * This interface might be implemented by application classes that - * define custom projections. + * An object-oriented representation of a query result set projection in a {@link Criteria} query. + * Built-in projection types are provided by the {@link Projections} factory class. This interface might be + * implemented by application classes that define custom projections. * + * @author Gavin King + * @author Steve Ebersole * @see Projections - * @see org.hibernate.Criteria - * @author Gavin King + * @see Criteria */ public interface Projection extends Serializable { /** - * Render the SQL fragment - * @param criteriaQuery - * @param columnAlias - * @return String - * @throws HibernateException + * Render the SQL fragment to be used in the <tt>SELECT</tt> clause. + * + * @param criteria The local criteria to which this project is attached (for resolution). + * @param position The number of columns rendered in the <tt>SELECT</tt> clause before this projection. Generally + * speaking this is useful to ensure uniqueness of the individual columns aliases. + * @param criteriaQuery The overall criteria query instance. + * @return The SQL fragment to plug into the <tt>SELECT</tt> + * @throws HibernateException Indicates a problem performing the rendering */ - public String toSqlString(Criteria criteria, int position, CriteriaQuery criteriaQuery) - throws HibernateException; - + public String toSqlString(Criteria criteria, int position, CriteriaQuery criteriaQuery) + throws HibernateException; + /** - * Render the SQL fragment to be used in the group by clause - * @param criteriaQuery - * @param columnAlias - * @return String - * @throws HibernateException + * Render the SQL fragment to be used in the <tt>GROUP BY</tt> clause + * + * @param criteria The local criteria to which this project is attached (for resolution). + * @param criteriaQuery The overall criteria query instance. + * @return The SQL fragment to plug into the <tt>GROUP BY</tt> + * @throws HibernateException Indicates a problem performing the rendering */ - public String toGroupSqlString(Criteria criteria, CriteriaQuery criteriaQuery) - throws HibernateException; - + public String toGroupSqlString(Criteria criteria, CriteriaQuery criteriaQuery) + throws HibernateException; + /** - * Return types returned by the rendered SQL fragment - * @param criteria - * @param criteriaQuery - * @return Type[] - * @throws HibernateException + * Types returned by the rendered SQL {@link #toSqlString fragment}. In other words what are the types + * that would represent the values this projection asked to be pulled into the result set? + * + * @param criteria The local criteria to which this project is attached (for resolution). + * @param criteriaQuery The overall criteria query instance. + * @return The return types. + * @throws HibernateException Indicates a problem resolving the types */ - public Type[] getTypes(Criteria criteria, CriteriaQuery criteriaQuery) - throws HibernateException; + public Type[] getTypes(Criteria criteria, CriteriaQuery criteriaQuery) + throws HibernateException; + /** - * Return types for a particular user-visible alias + * Get the return types for a particular user-visible alias. + * <p/> + * Differs from {@link #getTypes(org.hibernate.Criteria, CriteriaQuery)} in that here we are only interested in + * the types related to the given criteria-level alias. + * + * @param alias The criteria-level alias for which to find types. + * @param criteria The local criteria to which this project is attached (for resolution). + * @param criteriaQuery The overall criteria query instance. + * @return The return types; expected to return null if this projection does not understand this alias. + * @throws HibernateException Indicates a problem resolving the types */ - public Type[] getTypes(String alias, Criteria criteria, CriteriaQuery criteriaQuery) - throws HibernateException; - + public Type[] getTypes(String alias, Criteria criteria, CriteriaQuery criteriaQuery) + throws HibernateException; + + /** - * Get the SQL select clause column aliases + * Get the SQL column aliases used by this projection for the columns it writes for inclusion into the + * <tt>SELECT</tt> clause ({@link #toSqlString}. Hibernate always uses column aliases to extract data from the + * JDBC {@link java.sql.ResultSet}, so it is important that these be implemented correctly in order for + * Hibernate to be able to extract these val;ues correctly. + * + * @param position Just as in {@link #toSqlString}, represents the number of <b>columns</b> rendered + * prior to this projection. + * @return The columns aliases. */ - public String[] getColumnAliases(int loc); + public String[] getColumnAliases(int position); + /** - * Get the SQL select clause column aliases for a particular - * user-visible alias + * Get the SQL column aliases used by this projection for the columns it writes for inclusion into the + * <tt>SELECT</tt> clause ({@link #toSqlString} <i>for a particular criteria-level alias</i>. + * + * @param alias The criteria-level alias + * @param position Just as in {@link #toSqlString}, represents the number of <b>columns</b> rendered + * prior to this projection. + * @return The columns aliases pertaining to a particular criteria-level alias; expected to return null if + * this projection does not understand this alias. */ - public String[] getColumnAliases(String alias, int loc); - + public String[] getColumnAliases(String alias, int position); + /** - * Get the user-visible aliases for this projection - * (ie. the ones that will be passed to the - * <tt>ResultTransformer</tt>) + * Get the criteria-level aliases for this projection (ie. the ones that will be passed to the + * {@link org.hibernate.transform.ResultTransformer}) + * + * @return The aliases */ public String[] getAliases(); - + /** - * Does this projection specify grouping attributes? + * Is this projection fragment (<tt>SELECT</tt> clause) also part of the <tt>GROUP BY</tt> + * + * @return True if the projection is also part of the <tt>GROUP BY</tt>; false otherwise. */ public boolean isGrouped(); - + }