Does Spring Data JPA have any way to count entities using method name resolving?

Conquering complex count scenarios

Simple counts are easy, but Spring Data JPA doesn't abandon you when the counting gets complex.

Custom queries and parameters for counting

Got a count query that doesn't fit into the countBy method naming box? The @Query annotation is here as your superhero:

public interface OrderRepository extends JpaRepository<Order, Long> {
    @Query("SELECT COUNT(o) FROM Order o WHERE o.status = :status")
    long countByCustomStatus(@Param("status") String status); // "Spring, tell me, how many orders are still pending, huh?"
}
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This gives you a lot more control over the count query and allows for improved flexibility.

Example matchers for dynamic entity counting

Dealing with dynamic criteria based on entity properties? Spring Data JPA has a strategy for that use case - the Example matchers:

long count = userRepository.count(Example.of(userProbe)); // "Hey Spring, have you seen this user? How many like him do we have?"
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This comes in handy when the count criteria isn't static, but varies based on certain parameters.

Specifications for ultimate counting control

When method name resolving isn't robust enough for your complex counting needs, wave your flag for JPA Specifications:

public interface UserRepository extends JpaSpecificationExecutor<User>, JpaRepository<User, Long> {
    // "Spring, meet JPA Specifications, JPA Specifications, meet Spring."
}
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Using Specifications, you can build up a predicate with rich logic for our count query.

The many faces of entity counting

There are several ways to skin a cat, and several ways to count entities in Spring Data JPA. Let's dive deeper.

Paging through counts

Pagination is a common need, and combining it with count methods allow for seamless browsing through large datasets:

Page<User> users = userRepository.findByName("Smith", PageRequest.of(0, 10));
long totalSmithUsers = userRepository.countByName("Smith");
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Fetch a page of results and simultaneously get a total count of 'Smiths'. "Who said multitasking is impossible?"

Method names as count query generators

Since release 1.4 M1, Spring Data JPA has method names do a double act: they're not just methods, they're count query factories!

long countByLastNameStartingWith(String prefix); 
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Craft method names with conditions and let Spring Data handle the tedious job of query creation.

Count strategies for tenant-specific data

For multi-tenancy based applications, count data specific to a particular tenant with method name resolving:

long countByTenantName(String tenantName); 
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This tenant-specific data counting using method names, is one super convenient feature, as easy as sipping a cup of coffee (☕).