Add support for optional query parameters in repository methods [DATAMONGO-2486]

[spring-projects-issues]

shollander opened DATAMONGO-2486 and commented

I would be nice to be have optional parameters for a repository method/query. For example:

List<User> findByLastnameAndFirstname(String lastname, Optional<String> firstname)
 

If firstname contained a value then it would be included in the query. It it was empty then it would not be included in the query.

For example:

repository.findByLastnameAndFirstname("Smith", Optional.of("John"));
 

Would generate the following query:

{'lastname' : 'Smith', 'firstname' : 'John'}

While

repository.findByLastnameAndFirstname("Smith", Optional.of());
 

Would generate the following query:

{'lastname' : 'Smith'}

This is a simple example, but the value of this feature is realized when you have a query that contains many optional parameters. Creating all possible permutations can get very complicated. I believe having Optional would greatly simplify many use cases.

Note that while Optional can currently be used in a repository method parameter, it does not behave as expected. The current behavior is to query for a null value when passed Optional.empty(). I believe this is counter-intuitive since Spring Data MongoDB does not normally insert null fields in the database. If a field has a null value, that field does not exist in the mongo document

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Issue Links:

• DATACMNS-768 Support Optional on repository query parameters
  ("duplicates")
• DATACMNS-490 Add support for optional query method parameters
  ("duplicates")

[spring-projects-issues]

Mark Paluch commented

We already support Optional as argument in the sense of being a wrapper for null. This type of conversion is handled at Spring Data Commons level for a consistent functionality across all Spring Data modules so we cannot change this kind of behavior without breaking existing code