Module org.eclipse.persistence.core
Package org.eclipse.persistence.internal.jpa.jpql

Class JPQLQueryHelper

java.lang.Object
org.eclipse.persistence.internal.jpa.jpql.JPQLQueryHelper
public class JPQLQueryHelper extends Object
This helper can perform various operations over a JPQL query.
Since:
2.5
Version:
2.5

  • Constructor Details

    • JPQLQueryHelper

      public JPQLQueryHelper()
      Creates a new JPQLQueryHelper which uses the latest JPQL grammar.

    • JPQLQueryHelper

      public JPQLQueryHelper(JPQLGrammar jpqlGrammar)
      Creates a new JPQLQueryHelper.
      Parameters:
      jpqlGrammar - The JPQLGrammar that will determine how to parse JPQL queries
      Throws:
      NullPointerException - The JPQLGrammar cannot be null

  • Method Details

    • getClassDescriptors

      public List<ClassDescriptor> getClassDescriptors(CharSequence jpqlQuery, AbstractSession session)
      Retrieves the list of descriptors corresponding to the entities used throughout the given JPQL query.
      Parameters:
      jpqlQuery - The JPQL query used to gather the descriptors defined in the declaration clause
      session - The AbstractSession is used to retrieve the descriptors
      Returns:
      The list of descriptors used in the JPQL query or an empty list if the JPQL query is invalid or incomplete

    • getConstructorQueryMappings

      public List<ConstructorQueryMappings> getConstructorQueryMappings(AbstractSession session)
      Retrieves the class names and the attribute names mapped to their types that are used in the constructor expressions defined in the SELECT clause.
      For instance, from the following JPQL query: 
       SELECT new test.example.Employee(e.name, e.id),
        new test.example.Address(a.zipcode)
 FROM Employee e, Address a

      The return object is 
       |- test.example.Employee
 |-   |- name : String
 |-   |- id : int
 |- test.example.Address
      |- zipcode : int
      Parameters:
      session - The AbstractSession is used to retrieve the mappings used in the constructor items
      Returns:
      The holder of the result

    • getConstructorQueryMappings

      public ConstructorQueryMappings getConstructorQueryMappings(AbstractSession session, DatabaseQuery query)
      Retrieves the class names and the attribute names mapped to their types that are used in the constructor expressions defined in the SELECT clause.

      For instance, from the following JPQL query: 

       SELECT new test.example.Address(a.streetName, a.zipcode)
 FROM Address a

      The return object is 
       test.example.Address
    |- BasicMapping(streetName) : String
    |- BasicMapping(zipcode) : int
      Parameters:
      session - The AbstractSession is used to retrieve the mappings used in the constructor items
      Returns:
      The holder of the result

    • getGrammar

      public JPQLGrammar getGrammar()
      Returns the JPQL grammar that will be used to define how to parse a JPQL query.
      Returns:
      The grammar that will determine how to parse a JPQL query