org.apache.jdo.query
Interface QueryResultHelper

All Known Implementing Classes:
QueryResultHelperImpl

public interface QueryResultHelper

This interface is a helper for the query execution strategy of the StoreManager. When a query is executed, the filter is parsed. The parsed query, candidate collection or extent, and actual parameters of the execute are stored in the QueryResultHelper. This interface also provides methods useful for ordering the candidate objects and for filtering objects.

Version:
1.0
Author:
Craig Russell

Method Summary
 boolean applyFilter(java.lang.Object obj)
          This method determines whether the specified object is assignment compatible to the candidate Class specified by the user and satisfies the query filter.
 java.lang.Object getCandidates()
          Return the candidate Collection or Extent specified by the user.
 ValueTable getParameterValues()
          This method returns the parameter values passed by the user in the execute(...) method.
 QueryTree getQueryTree()
          Return the query tree which is either specified by the user or compiled from a JDOQL query.
 java.util.List orderCandidates(java.util.Collection candidates)
          This method filters the specified collection, removing all elements that are not assignment compatible to the candidate Class specified by the user, and then orders the results according to the ordering expression specified by the user.
 

Method Detail

getCandidates

public java.lang.Object getCandidates()
Return the candidate Collection or Extent specified by the user.

Returns:
the candidate Collection or Extent.

orderCandidates

public java.util.List orderCandidates(java.util.Collection candidates)
This method filters the specified collection, removing all elements that are not assignment compatible to the candidate Class specified by the user, and then orders the results according to the ordering expression specified by the user. A new List is returned.

Parameters:
candidates - the collection of instances to be filtered and ordered
Returns:
the filtered parameter collection ordered by the ordering expression.

applyFilter

public boolean applyFilter(java.lang.Object obj)
This method determines whether the specified object is assignment compatible to the candidate Class specified by the user and satisfies the query filter.

Parameters:
obj - the candidate object.
Returns:
true if the specified object is of the candidate class and satisfies the query filter; false otherwise

getQueryTree

public QueryTree getQueryTree()
Return the query tree which is either specified by the user or compiled from a JDOQL query.

Returns:
the query tree

getParameterValues

public ValueTable getParameterValues()
This method returns the parameter values passed by the user in the execute(...) method.

Returns:
a ValueTable representing the parameter values