findTop3ByCategoryAndInStockTrueOrderByPriceAscString

findTop3ByCate... is an example of a Spring Data JPA derived query method. Methods in Spring Data repositories can encode the query logic in the method name. The Top3 part indicates that the method should return at most three results, while the By introduces the filtering criteria. The remainder specifies the property path used for filtering, such as category, categoryId, or categoryName. Such methods are declared in a repository interface that typically extends JpaRepository or a related interface, and Spring generates the implementation at runtime.

How it works: Spring analyzes the method name and translates it into a JPQL or SQL query. For example, a method like List<Product> findTop3ByCategoryIdOrderByRatingDesc(Long categoryId) returns up to three Product records with the given categoryId, ordered by rating in descending order. Another common form is List<Article> findTop3ByCategoryAndStatusOrderByPublishDateDesc(Category category, Status status), which filters by multiple criteria and orders by a specified field.

Return types and ordering: The typical return type is List<T>, since the result is limited to three items. To ensure deterministic results, an explicit OrderBy clause is recommended. There are also synonyms such as findFirst3By... or findTop3By... that convey the same intent, depending on naming preferences.

Limitations and usage notes: The method name must map to existing entity properties; overly long or complex criteria may require custom queries via @Query or a dedicated implementation. Without an explicit order, the database may return results in an unpredictable order.

Practical use: This pattern is useful for showing featured, trending, or preview items within a category, such as top three products in a category or recent top three posts.