Explore if it makes sense to provide an EvaluationContextExtension supports optional/null query parameters.

[christophstrobl]

Using @Query to skip entire criteria entries when given a null value is cumbersome at the moment but could be done as follows.

interface Repo extends CrudRepository<Person,...> {
  @Query("""
         { $and : [ 
            ?#{T(com.example.Repo.QueryUtil).ifPresent([0], 'name')}, 
            ?#{T(com.example.Repo.QueryUtil).ifPresent([1], 'city')},
            ... 
         ]}
         """)
  List<Person> findByNameAndCity(@Nullable String name, @Nullable String city, ...);

  class QueryUtil {
    public static Document ifPresent(Object value, String property) {
      if(value == null) {
        return new Document("$expr", true); // always true
      }
      return new Document(property, value); // eq match
    }
  }
  // ...
}

Providing an EvaluationContextExtension with predefined methods might help ease a lot of pain.

[sbernardo]

Another approach could be this:

interface Repo extends CrudRepository<Person,...> {

  @Query("""
         { $and : [ 
            ?#{ [0] == null ? { $expr: true } : { "name" : [0] } }, 
            ?#{ [1] == null ? { $expr: true } : { "city" : { $in: [1] } } },
            ... 
         ]}
         """)
  List<Person> findByNameAndCity(@Nullable String name, @Nullable List<String> city, ...);

  // ...
}

With this solution, you can use other operators (like $in) directly using SpEL, without the need for external classes.