Collection/varargs utility methods for composing Specifications [DATAJPA-1651]

[spring-projects-issues]

Daniel Shuy Yaw Yong opened DATAJPA-1651 and commented

Currently, when handling multiple conditional Specifications, the code looks something like:

Specification<User> specification = Specification.where(null);
if (nameFilter != null && !nameFilter.isEmpty()) {
  specification = specification.and(specifications.hasName(nameFilter));
}
if (typeFilter != null) {
  specification = specification.and(specifications.hasType(typeFilter));
}
if (archivedFilter != null) {
  specification = specification.and(specifications.isArchived(archived));
}
if (searchPattern != null && !searchPattern.isEmpty()) {
  specification = specification.and(
    specifications.nameLike(searchPattern).or(
      specifications.addressLike(searchPattern)));
}

return repository.findAll(specification);

This approach has the following disadvantages:

• It is quite verbose
• Some IDEs will emit potential NullPointerException warnings on the Specification#and(Specification) calls (because Specification#where(Specification) is @Nullable)
• It forces us to mutate the specification variable
• Can get very messy when nesting multiple AND/OR operations

 

This is a feature request to add static utility methods to create conjunctions/disjuntions of Collections/varargs of Specifications, similar to Querydsl's ExpressionUtils#allOf(Collection) / ExpressionUtils#allOf(Predicate...) / ExpressionUtils#anyOf(Collection) / ExpressionUtils#anyOf(Predicate...)

 

This will allow for better structured code when handling multiple conditional Specifications, eg. using the same example above:

var specification = Specification.allOf(
    nameFilter != null && !nameFilter.isEmpty() ? specifications.hasName(nameFilter) : null,
    typeFilter != null ? specifications.hasType(typeFilter) : null,
    archivedFilter != null ? specifications.isArchived(archivedFilter) : null),
    searchPattern != null && !searchPattern.isEmpty() ? Specification.anyOf(
        specifications.nameLike(searchPattern),
        specifications.addressLike(searchPattern));

return repository.findAll(specification);

 

 

---

Issue Links:

• DATAJPA-1622 Nullable annotations used for non-null returning Specification methods

Referenced from: pull request #404

[spring-projects-issues]

Oliver Drotbohm commented

This is going to be part of a major revamp of our Specification story for the release train post Neumann. Rest assured we will get to that but it will very likely to be post Neumann release, currently scheduled for May