java - Spring JPA Query returns Null instead of List -


i have @entity video having one-to-many relation list<tag> tags 1 of fields. use following @repository using spring data popular tags:

@repository public interface tagrepository extends crudrepository<tag, integer>{     @query("select t tag t (select sum(v.views) video v t member of v.tags) > 0")     public list<tag> findmostviewedtags(int maxtags); }

the query processed , considered valid spring, tested generated sql vs database locally , returned 2 tags. in code however, receive value null when call method findmostviewedtags(100).

the query lookup strategy default "create_if_not_found".

  1. if there no results found, should method return empty list or null? desired behavior receive empty list.
  2. why method call return null instead of list<tag> size() 2?

  1. the normal behavior indeed returning empty list if no results found. if list<object> return value of method in defined interface, method should never return null.
  2. the problem parameter given method , not used anywhere in query. reason spring decides return null in case. solution: remove unused parameter or use parameter in query.

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