How to avoid hardcoding a JPA entity property name in the Sort.by(...) sorted paginated request handler?

Question

I am using the an entity that has multiple properties/table columns:

@Entity
public class History {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @NotNull
    @Column
    ZonedDateTime dateCreated;

    @NotNull
    @Column
    private ZonedDateTime dateValidFrom;

    ...

and I have a Spring MVC controller with a handler that returns such History entries sorted by a particular property (e.g. dateValidFrom). The code below is from the HistoryService:

public List<History> findAll(int page, int pageSize) {
    PageRequest pageSettings = PageRequest.of(page, pageSize, Sort.by(Sort.Direction.ASC, "dateValidFrom"));
    return historyRepo.findAll(pageSettings).stream().collect(Collectors.toList());
}

How can I avoid using the hardcoded dateValidFrom property name and have a type-safe construct (detecting renaming mistakes at compile-time)?

I am assuming that I want a certain fixed (or some default sorting property). And even if I add it as a parameter, it will popup in the Controller where I will still have to hardcode it or even worse, let the user write the property name. I would like to say something like `History. ...` or somehow an enum that is bound then in the `History` entity to the properties as names. — Gabriel Petrovay, Aug 01 '21 at 22:52
Perhaps either something in the Criteria API (here be dragons) or Lombok's `@FieldNameConstants`. — chrylis -cautiouslyoptimistic-, Aug 01 '21 at 23:01

SaleemKhair · Answer 1 · 2021-08-01T23:47:38.143

0

JPA 2 defines a typesafe Criteria API which allows Criteria queries to be constructed in a strongly-typed manner, utilizing so called static metamodel classes. see: JPA Static Model Generator

These models are static classes that allows you to: _History.dateValidFrom which returns a string of the field name, thus avoiding hardcoded strings.

Check this answer for how to generate those static models:

edited Aug 01 '21 at 23:47

answered Aug 01 '21 at 23:41

SaleemKhair

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How to avoid hardcoding a JPA entity property name in the Sort.by(...) sorted paginated request handler?

1 Answers1