DATAJPA-665 - Add QueryDslJpaRepository.exists(…) method wich accepts a Querydsl predicate.

Introduced QueryDslJpaRepository.exists(Predicate) method to QueryDslJpaRepository.

Related ticket: DATACMNS-636.
Original pull request: #131.

Author: Thomas Darimont

src/main/java/org/springframework/data/jpa/repository/support/QueryDslJpaRepository.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2012 the original author or authors.
+ * Copyright 2008-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,6 +46,7 @@
  * {@link QueryDslPredicateExecutor}.
  * 
  * @author Oliver Gierke
+ * @author Thomas Darimont
  */
 public class QueryDslJpaRepository<T, ID extends Serializable> extends SimpleJpaRepository<T, ID> implements
 		QueryDslPredicateExecutor<T> {
@@ -142,6 +143,13 @@ public long count(Predicate predicate) {
 		return createQuery(predicate).count();
 	}
 
+	/* (non-Javadoc)
+	 * @see org.springframework.data.querydsl.QueryDslPredicateExecutor#exists(com.mysema.query.types.Predicate)
+	 */
+	public boolean exists(Predicate predicate) {
+		return createQuery(predicate).exists();
+	}
+
 	/**
 	 * Creates a new {@link JPQLQuery} for the given {@link Predicate}.
 	 * 

src/test/java/org/springframework/data/jpa/repository/support/QueryDslJpaRepositoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2014 the original author or authors.
+ * Copyright 2008-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -325,4 +325,15 @@ public void shouldSupportSortByOperatorWithDateExpressions() {
 		assertThat(users, hasSize(3));
 		assertThat(users, hasItems(dave, carter, oliver));
 	}
+
+	/**
+	 * @see DATAJPA-665
+	 */
+	@Test
+	public void shouldSupportExistsWithPredicate() throws Exception {
+
+		assertThat(repository.exists(user.firstname.eq("Dave")), is(true));
+		assertThat(repository.exists(user.firstname.eq("Unknown")), is(false));
+		assertThat(repository.exists((Predicate) null), is(true));
+	}
 }