How to implement user defined function using eclipselink ?

[suraj-mane-zellis]

As suggested in issue - #238 . I have exclude hibernate and use eclipse library for jpa implementation . We had implement custom function which supported in hibernate and how we can implement same in eclipse link

Implementation with Hibernate :

      import org.hibernate.boot.MetadataBuilder;
      import org.hibernate.dialect.function.SQLFunctionTemplate;
      import org.hibernate.type.StandardBasicTypes;

  public class TestMetadataBuilderContributor {

  public static void commonSqlFunctions(MetadataBuilder metadataBuilder) {
    metadataBuilder.applySqlFunction("cast_as_time", new SQLFunctionTemplate(StandardBasicTypes.TIME,
            "cast(?1 as time)"));
    metadataBuilder.applySqlFunction("cast_as_date", new SQLFunctionTemplate(StandardBasicTypes.DATE,
            "cast(?1 as date)"));
    
             }
         }

olingo-jpa-processor-v4 - Custom implementation in JPAOperationConverter.class

 case DATE:
  
  return cb.function("cast_as_date", Date.class, (Expression<Timestamp>) jpaFunction.getParameter(0).get());

I have gone through eclipse link official document , I have found something .

https://wiki.eclipse.org/Introduction_to_EclipseLink_Expressions_(ELUG)#Creating_and_Using_a_User-Defined_Function

Can you please provide how we can implement database specific custom function in jpa processor side using eclipse link?

[wog48]

Actually, I'm not sure if I can help. I never tried to add a database function to the JPA Metadata. Nevertheless, with version 2.0.2 the problems with Hibernate shall be solved and you can try to use it again.

In case you like to find ut, how you can make use of database function with in OData request, you may find Functions helpful.