DATAMONGO-1454 - Add support for exists projection in repository query methods.

We now support exists projections for query methods in query methods for derived and string queries.

public PersonReposotiry extends Repository<Person, String> {

  boolean existsByFirstname(String firstname);

  @query(value = "{ 'lastname' : ?0 }", exists = true)
  boolean someExistQuery(String lastname);
}

Author: mp911de

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/Query.java

@@ -62,6 +62,14 @@
 	 */
 	boolean count() default false;
 
+	/**
+	 * Returns whether the query defined should be executed as exists projection.
+	 *
+	 * @since 1.10
+	 * @return
+	 */
+	boolean exists() default false;
+
 	/**
 	 * Returns whether the query should delete matching documents.
 	 * 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/AbstractMongoQuery.java

@@ -20,7 +20,9 @@
 import org.springframework.data.mongodb.core.MongoOperations;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.repository.query.MongoQueryExecution.CollectionExecution;
+import org.springframework.data.mongodb.repository.query.MongoQueryExecution.CountExecution;
 import org.springframework.data.mongodb.repository.query.MongoQueryExecution.DeleteExecution;
+import org.springframework.data.mongodb.repository.query.MongoQueryExecution.ExistsExecution;
 import org.springframework.data.mongodb.repository.query.MongoQueryExecution.GeoNearExecution;
 import org.springframework.data.mongodb.repository.query.MongoQueryExecution.PagedExecution;
 import org.springframework.data.mongodb.repository.query.MongoQueryExecution.PagingGeoNearExecution;
@@ -40,6 +42,7 @@
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public abstract class AbstractMongoQuery implements RepositoryQuery {
 
@@ -123,8 +126,12 @@ private MongoQueryExecution getExecutionToWrap(Query query, MongoParameterAccess
 			return new CollectionExecution(operations, accessor.getPageable());
 		} else if (method.isPageQuery()) {
 			return new PagedExecution(operations, accessor.getPageable());
+		} else if (isCountQuery()) {
+			return new CountExecution(operations);
+		} else if (isExistsQuery()) {
+			return new ExistsExecution(operations);
 		} else {
-			return new SingleEntityExecution(operations, isCountQuery());
+			return new SingleEntityExecution(operations);
 		}
 	}
 
@@ -164,6 +171,14 @@ protected Query createCountQuery(ConvertingParameterAccessor accessor) {
 	 */
 	protected abstract boolean isCountQuery();
 
+	/**
+	 * Returns whether the query should get an exists projection applied.
+	 *
+	 * @return
+	 * @since 1.10
+	 */
+	protected abstract boolean isExistsQuery();
+
 	/**
 	 * Return weather the query should delete matching documents.
 	 * 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/MongoQueryExecution.java

@@ -163,15 +163,57 @@ public long get() {
 	static final class SingleEntityExecution implements MongoQueryExecution {
 
 		private final MongoOperations operations;
-		private final boolean countProjection;
 
 		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.repository.query.AbstractMongoQuery.Execution#execute(org.springframework.data.mongodb.core.query.Query, java.lang.Class, java.lang.String)
 		 */
 		@Override
 		public Object execute(Query query, Class<?> type, String collection) {
-			return countProjection ? operations.count(query, type, collection) : operations.findOne(query, type, collection);
+			return operations.findOne(query, type, collection);
+		}
+	}
+
+	/**
+	 * {@link MongoQueryExecution} to perform a count projection.
+	 *
+	 * @author Oliver Gierke
+	 * @author Mark Paluch
+	 * @since 1.10
+	 */
+	@RequiredArgsConstructor
+	static final class CountExecution implements MongoQueryExecution {
+
+		private final MongoOperations operations;
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.repository.query.AbstractMongoQuery.Execution#execute(org.springframework.data.mongodb.core.query.Query, java.lang.Class, java.lang.String)
+		 */
+		@Override
+		public Object execute(Query query, Class<?> type, String collection) {
+			return operations.count(query, type, collection);
+		}
+	}
+
+	/**
+	 * {@link MongoQueryExecution} to perform an exists projection.
+	 *
+	 * @author Mark Paluch
+	 * @since 1.10
+	 */
+	@RequiredArgsConstructor
+	static final class ExistsExecution implements MongoQueryExecution {
+
+		private final MongoOperations operations;
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.data.mongodb.repository.query.AbstractMongoQuery.Execution#execute(org.springframework.data.mongodb.core.query.Query, java.lang.Class, java.lang.String)
+		 */
+		@Override
+		public Object execute(Query query, Class<?> type, String collection) {
+			return operations.exists(query, type, collection);
 		}
 	}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/PartTreeMongoQuery.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -38,6 +38,7 @@
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public class PartTreeMongoQuery extends AbstractMongoQuery {
 
@@ -139,6 +140,15 @@ protected boolean isCountQuery() {
 		return tree.isCountProjection();
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.repository.query.AbstractMongoQuery#isExistsQuery()
+	 */
+	@Override
+	protected boolean isExistsQuery() {
+		return tree.isExistsProjection();
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.repository.query.AbstractMongoQuery#isDeleteQuery()

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/query/StringBasedMongoQuery.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2015 the original author or authors.
+ * Copyright 2011-2016 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.
@@ -42,16 +42,18 @@
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public class StringBasedMongoQuery extends AbstractMongoQuery {
 
-	private static final String COUND_AND_DELETE = "Manually defined query for %s cannot be both a count and delete query at the same time!";
+	private static final String COUNT_EXISTS_AND_DELETE = "Manually defined query for %s cannot be a count and exists or delete query at the same time!";
 	private static final Logger LOG = LoggerFactory.getLogger(StringBasedMongoQuery.class);
 	private static final ParameterBindingParser BINDING_PARSER = ParameterBindingParser.INSTANCE;
 
 	private final String query;
 	private final String fieldSpec;
 	private final boolean isCountQuery;
+	private final boolean isExistsQuery;
 	private final boolean isDeleteQuery;
 	private final List<ParameterBinding> queryParameterBindings;
 	private final List<ParameterBinding> fieldSpecParameterBindings;
@@ -96,10 +98,11 @@ public StringBasedMongoQuery(String query, MongoQueryMethod method, MongoOperati
 				method.getFieldSpecification(), this.fieldSpecParameterBindings);
 
 		this.isCountQuery = method.hasAnnotatedQuery() ? method.getQueryAnnotation().count() : false;
+		this.isExistsQuery = method.hasAnnotatedQuery() ? method.getQueryAnnotation().exists() : false;
 		this.isDeleteQuery = method.hasAnnotatedQuery() ? method.getQueryAnnotation().delete() : false;
 
-		if (isCountQuery && isDeleteQuery) {
-			throw new IllegalArgumentException(String.format(COUND_AND_DELETE, method));
+		if (hasTwoQueryExecutions(this.isCountQuery, this.isExistsQuery, this.isDeleteQuery)) {
+			throw new IllegalArgumentException(String.format(COUNT_EXISTS_AND_DELETE, method));
 		}
 
 		this.parameterBinder = new ExpressionEvaluatingParameterBinder(expressionParser, evaluationContextProvider);
@@ -135,6 +138,15 @@ protected boolean isCountQuery() {
 		return isCountQuery;
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.mongodb.repository.query.AbstractMongoQuery#isExistsQuery()
+	 */
+	@Override
+	protected boolean isExistsQuery() {
+		return isExistsQuery;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.mongodb.repository.query.AbstractMongoQuery#isDeleteQuery()
@@ -144,6 +156,10 @@ protected boolean isDeleteQuery() {
 		return this.isDeleteQuery;
 	}
 
+	private boolean hasTwoQueryExecutions(boolean isCountQuery, boolean isExistsQuery, boolean isDeleteQuery) {
+		return isCountQuery ? (isExistsQuery || isDeleteQuery) : (isExistsQuery && isDeleteQuery);
+	}
+
 	/**
 	 * A parser that extracts the parameter bindings from a given query string.
 	 * 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/AbstractPersonRepositoryIntegrationTests.java

@@ -588,6 +588,23 @@ public void executesAnnotatedCountProjection() {
 		assertThat(repository.someCountQuery("Matthews"), is(2L));
 	}
 
+	/**
+	 * @see DATAMONGO-1454
+	 */
+	@Test
+	public void executesDerivedExistsProjectionToBoolean() {
+		assertThat(repository.existsByFirstname("Oliver August"), is(true));
+		assertThat(repository.existsByFirstname("Hans Peter"), is(false));
+	}
+
+	/**
+	 * @see DATAMONGO-1454
+	 */
+	@Test
+	public void executesAnnotatedExistProjection() {
+		assertThat(repository.someExistQuery("Matthews"), is(true));
+	}
+
 	/**
 	 * @see DATAMONGO-701
 	 */

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/PersonRepository.java

@@ -42,6 +42,7 @@
  * @author Oliver Gierke
  * @author Thomas Darimont
  * @author Christoph Strobl
+ * @author Mark Paluch
  */
 public interface PersonRepository extends MongoRepository<Person, String>, QueryDslPredicateExecutor<Person> {
 
@@ -250,6 +251,17 @@ public interface PersonRepository extends MongoRepository<Person, String>, Query
 	@Query(value = "{ 'lastname' : ?0 }", count = true)
 	long someCountQuery(String lastname);
 
+	/**
+	 * @see DATAMONGO-1454
+	 */
+	boolean existsByFirstname(String firstname);
+
+	/**
+	 * @see DATAMONGO-1454
+	 */
+	@Query(value = "{ 'lastname' : ?0 }", exists = true)
+	boolean someExistQuery(String lastname);
+
 	/**
 	 * @see DATAMONGO-770
 	 */

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/AbstractMongoQueryUnitTests.java

@@ -312,6 +312,7 @@ private MongoQueryFake createQueryForMethod(String methodName, Class<?>... param
 	private static class MongoQueryFake extends AbstractMongoQuery {
 
 		private boolean isCountQuery;
+		private boolean isExistsQuery;
 		private boolean isDeleteQuery;
 
 		public MongoQueryFake(MongoQueryMethod method, MongoOperations operations) {
@@ -328,6 +329,11 @@ protected boolean isCountQuery() {
 			return isCountQuery;
 		}
 
+		@Override
+		protected boolean isExistsQuery() {
+			return false;
+		}
+
 		@Override
 		protected boolean isDeleteQuery() {
 			return isDeleteQuery;