How to configure query by example to include null values?

Question

I have the following matcher:

Example.of(
    user,
    ExampleMatcher.matching()
                  .withMatcher("name", contains().ignoreCase())
                  .withMatcher("phoneNumber", contains())
)

It works fine except null values. For example, it doesn't return the users whose phone number is NULL.

I have tried to following to include the NULL values but it didn't work:

Example.of(
    user,
    ExampleMatcher.matching()
                  .withMatcher("name", contains().ignoreCase())
                      .withIncludeNullValues()
                  .withMatcher("phoneNumber", contains())
                      .withIncludeNullValues()
)

The generated SQL is the following:

select
    user0_.id as id1_9_,
    user0_.document_expiry_date as document2_9_,
    user0_.document_type as document3_9_,
    user0_.document_url as document4_9_,
    user0_.email as email5_9_,
    user0_.name as name6_9_,
    user0_.phone_number as phone_nu7_9_
from
    user user0_
where
    (lower(user0_.name) like ?)
    and (user0_.id is null)
    and (user0_.document_type is null)
    and (user0_.document_url is null)
    and (user0_.email is null)
    and (user0_.phone_number like ?)
    and (user0_.document_expiry_date is null)

How can I configure it to include rows with NULL columns as well?

Answer 1

Confronted the same problem, but I think there is no way to accomplish this goal. Here is the source code of method withMatcher:

public ExampleMatcher withMatcher(String propertyPath, ExampleMatcher.GenericPropertyMatcher genericPropertyMatcher) {
    Assert.hasText(propertyPath, "PropertyPath must not be empty!");
    Assert.notNull(genericPropertyMatcher, "GenericPropertyMatcher must not be empty!");
    ExampleMatcher.PropertySpecifiers propertySpecifiers = new ExampleMatcher.PropertySpecifiers(this.propertySpecifiers);
    ExampleMatcher.PropertySpecifier propertySpecifier = new ExampleMatcher.PropertySpecifier(propertyPath);
    if (genericPropertyMatcher.ignoreCase != null) {
        propertySpecifier = propertySpecifier.withIgnoreCase(genericPropertyMatcher.ignoreCase);
    }

    if (genericPropertyMatcher.stringMatcher != null) {
        propertySpecifier = propertySpecifier.withStringMatcher(genericPropertyMatcher.stringMatcher);
    }

    if (genericPropertyMatcher.valueTransformer != null) {
        propertySpecifier = propertySpecifier.withValueTransformer(genericPropertyMatcher.valueTransformer);
    }

    propertySpecifiers.add(propertySpecifier);
    return new ExampleMatcher(this.nullHandler, this.defaultStringMatcher, propertySpecifiers, this.ignoredPaths, this.defaultIgnoreCase, this.mode);
}

this method returns a ExampleMatcher with the 'global' nullHandler which applied to all the fields. That means, you can't specify a different nullHander for some special fields.

Answer 2

You can implements JpaSpecificationExecutor<T> in your repository and use findAll(Specification specification), and set like param:

//My solution, create a specification with predicate and add example.
 public Specification<MaestroPlasticoTebca> specificationAttributeNull(boolean isNull, Example<MaestroPlasticoTebca> example, String attributeName) {
        return (root, query, builder) -> {
            final List<Predicate> predicates = new ArrayList<>();

            if (isNull) {
                predicates.add(builder.isNull(root.get(attributeName)));
            } else {
                predicates.add(builder.isNotNull(root.get(attributeName)));
            }

            predicates.add(QueryByExamplePredicateBuilder.getPredicate(root, builder, example));
            return builder.and(predicates.toArray(new Predicate[0]));
        };

    }

And use it:

Example example = Example.of(
    user,
    ExampleMatcher.matching()
                  .withMatcher("name", contains().ignoreCase())
);

repository.findAll(specificationAttributeNull(true, example, "phoneNumber"));