How to sort PageRequest on String as numeric value

Question

I currently have a system in place which can filter and sort records in the database and return them as a Paged object. One of the lines is like this:

final          


        

Answer 1

Assume that you have entity with a String filed and you want to sort it like Long with jpa Pageable.

So you need to do following things:(Remember this only works with Oracle Database)

1. Add a new filed in your entity with Long type
2. for the new filed use @Formula in getter method and evoke to_number()

@Entity
public class testEntity{
         private String oldField;  //Getter and Setter

         private Long newField; //Setter

         @Formula(value = "to_number(oldField)")
         public Long getNewField() {
                return newField;
         } 
 }

3. in your service find sorted filed and change it to the newfiled

 if (Objects.nonNull(pagingRequest.getSort()) && pagingRequest.getSort().getFieldName().equals("oldField")) {
            pagingRequest.getSort().setFieldName("newField");
 }