DATAMONGO-1325 - Polishing.

Add since tag to new method. Set year of inception in copyright header. Add ticket reference to test. Minor code reformatting. Add integration test.

Change query keyword for query-by-example from $sample to $example to prevent accidental collisions.

Remove Mongo 3.4-next build profile due to removed Mongo 3.4 driver snapshots.

Original pull request: #452.

.travis.yml

@@ -9,7 +9,6 @@ before_script:
 env:
   matrix:
     - PROFILE=ci
-    - PROFILE=mongo34-next
     - PROFILE=mongo35-next
 
 # Current MongoDB version is 2.4.2 as of 2016-04, see https://github.com/travis-ci/travis-ci/issues/3694

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/Aggregation.java

@@ -17,7 +17,6 @@ package org.springframework.data.mongodb.core.aggregation;
 
 import static org.springframework.data.mongodb.core.aggregation.Fields.*;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
@@ -25,15 +24,10 @@ import org.bson.Document;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Sort.Direction;
 import org.springframework.data.mongodb.core.aggregation.CountOperation.CountOperationBuilder;
-import org.springframework.data.mongodb.core.aggregation.ExposedFields.DirectFieldReference;
-import org.springframework.data.mongodb.core.aggregation.ExposedFields.ExposedField;
-import org.springframework.data.mongodb.core.aggregation.ExposedFields.FieldReference;
 import org.springframework.data.mongodb.core.aggregation.FacetOperation.FacetOperationBuilder;
-import org.springframework.data.mongodb.core.aggregation.FieldsExposingAggregationOperation.InheritsFieldsAggregationOperation;
 import org.springframework.data.mongodb.core.aggregation.GraphLookupOperation.StartWithBuilder;
 import org.springframework.data.mongodb.core.aggregation.ReplaceRootOperation.ReplaceRootDocumentOperationBuilder;
 import org.springframework.data.mongodb.core.aggregation.ReplaceRootOperation.ReplaceRootOperationBuilder;
-import org.springframework.data.mongodb.core.aggregation.Fields.*;
 import org.springframework.data.mongodb.core.query.Criteria;
 import org.springframework.data.mongodb.core.query.CriteriaDefinition;
 import org.springframework.data.mongodb.core.query.NearQuery;
@@ -384,15 +378,16 @@ public class Aggregation {
 	}
 
 	/**
-	 * Creates a new {@link SampleOperation} to selects the specified number of documents from its input randomly.
+	 * Creates a new {@link SampleOperation} to select the specified number of documents from its input randomly.
 	 *
 	 * @param sampleSize must not be less than zero.
 	 * @return
+	 * @since 2.0
 	 */
 	public static SampleOperation sample(long sampleSize) {
 		return new SampleOperation(sampleSize);
 	}
-	
+
 	/**
 	 * Creates a new {@link MatchOperation} using the given {@link Criteria}.
 	 *

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/aggregation/SampleOperation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2017 the original author or authors.
+ * Copyright 2017 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.
@@ -26,7 +26,8 @@ import org.springframework.util.Assert;
  *
  * @author Gustavo de Geus
  * @since 2.0
- * @see <a href="https://docs.mongodb.com/master/reference/operator/aggregation/sample/">MongoDB Aggregation Framework: $sample</a>
+ * @see <a href="https://docs.mongodb.com/master/reference/operator/aggregation/sample/">MongoDB Aggregation Framework:
+ *      $sample</a>
  */
 public class SampleOperation implements AggregationOperation {
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/QueryMapper.java

@@ -57,7 +57,7 @@ import com.mongodb.DBRef;
 
 /**
  * A helper class to encapsulate any modifications of a Query object before it gets submitted to the database.
- * 
+ *
  * @author Jon Brisbin
  * @author Oliver Gierke
  * @author Patryk Wasik
@@ -82,7 +82,7 @@ public class QueryMapper {
 
 	/**
 	 * Creates a new {@link QueryMapper} with the given {@link MongoConverter}.
-	 * 
+	 *
 	 * @param converter must not be {@literal null}.
 	 */
 	public QueryMapper(MongoConverter converter) {
@@ -102,7 +102,7 @@ public class QueryMapper {
 	/**
 	 * Replaces the property keys used in the given {@link Document} with the appropriate keys by using the
 	 * {@link PersistentEntity} metadata.
-	 * 
+	 *
 	 * @param query must not be {@literal null}.
 	 * @param entity can be {@literal null}.
 	 * @return
@@ -155,7 +155,7 @@ public class QueryMapper {
 	/**
 	 * Maps fields used for sorting to the {@link MongoPersistentEntity}s properties. <br />
 	 * Also converts properties to their {@code $meta} representation if present.
-	 * 
+	 *
 	 * @param sortObject
 	 * @param entity
 	 * @return
@@ -179,7 +179,7 @@ public class QueryMapper {
 	/**
 	 * Maps fields to retrieve to the {@link MongoPersistentEntity}s properties. <br />
 	 * Also onverts and potentially adds missing property {@code $meta} representation.
-	 * 
+	 *
 	 * @param fieldsObject
 	 * @param entity
 	 * @return
@@ -217,7 +217,7 @@ public class QueryMapper {
 
 	/**
 	 * Extracts the mapped object value for given field out of rawValue taking nested {@link Keyword}s into account
-	 * 
+	 *
 	 * @param field
 	 * @param rawValue
 	 * @return
@@ -250,7 +250,7 @@ public class QueryMapper {
 
 	/**
 	 * Returns the given {@link Document} representing a keyword by mapping the keyword's value.
-	 * 
+	 *
 	 * @param keyword the {@link Document} representing a keyword (e.g. {@code $ne : … } )
 	 * @param entity
 	 * @return
@@ -280,7 +280,7 @@ public class QueryMapper {
 
 	/**
 	 * Returns the mapped keyword considered defining a criteria for the given property.
-	 * 
+	 *
 	 * @param property
 	 * @param keyword
 	 * @return
@@ -299,7 +299,7 @@ public class QueryMapper {
 	/**
 	 * Returns the mapped value for the given source object assuming it's a value for the given
 	 * {@link MongoPersistentProperty}.
-	 * 
+	 *
 	 * @param value the source object to be mapped
 	 * @param property the property the value is a value for
 	 * @param newKey the key the value will be bound to eventually
@@ -368,7 +368,7 @@ public class QueryMapper {
 	 * requires conversion to a {@link org.springframework.data.mongodb.core.mapping.DBRef} object. We check whether the
 	 * type of the given value is compatible with the type of the given document field in order to deal with potential
 	 * query field exclusions, since MongoDB uses the {@code int} {@literal 0} as an indicator for an excluded field.
-	 * 
+	 *
 	 * @param documentField must not be {@literal null}.
 	 * @param value
 	 * @return
@@ -399,7 +399,7 @@ public class QueryMapper {
 
 	/**
 	 * Retriggers mapping if the given source is a {@link Document} or simply invokes the
-	 * 
+	 *
 	 * @param source
 	 * @param entity
 	 * @return
@@ -432,7 +432,7 @@ public class QueryMapper {
 	/**
 	 * Converts the given source Object to a mongo type with the type information of the original source type omitted.
 	 * Subclasses may overwrite this method to retain the type information of the source type on the resulting mongo type.
-	 * 
+	 *
 	 * @param source
 	 * @param entity
 	 * @return the converted mongo type or null if source is null
@@ -447,7 +447,7 @@ public class QueryMapper {
 
 	/**
 	 * Converts the given source assuming it's actually an association to another object.
-	 * 
+	 *
 	 * @param source
 	 * @param property
 	 * @return
@@ -486,7 +486,7 @@ public class QueryMapper {
 
 	/**
 	 * Checks whether the given value is a {@link Document}.
-	 * 
+	 *
 	 * @param value can be {@literal null}.
 	 * @return
 	 */
@@ -506,7 +506,7 @@ public class QueryMapper {
 
 	/**
 	 * Creates a new {@link Entry} for the given {@link Field} with the given value.
-	 * 
+	 *
 	 * @param field must not be {@literal null}.
 	 * @param value can be {@literal null}.
 	 * @return
@@ -517,7 +517,7 @@ public class QueryMapper {
 
 	/**
 	 * Creates a new {@link Entry} with the given key and value.
-	 * 
+	 *
 	 * @param key must not be {@literal null} or empty.
 	 * @param value can be {@literal null}
 	 * @return
@@ -543,7 +543,7 @@ public class QueryMapper {
 
 	/**
 	 * Converts the given raw id value into either {@link ObjectId} or {@link String}.
-	 * 
+	 *
 	 * @param id
 	 * @return
 	 */
@@ -566,7 +566,7 @@ public class QueryMapper {
 
 	/**
 	 * Returns whether the given {@link Object} is a keyword, i.e. if it's a {@link Document} with a keyword key.
-	 * 
+	 *
 	 * @param candidate
 	 * @return
 	 */
@@ -588,7 +588,7 @@ public class QueryMapper {
 	/**
 	 * Returns whether the given {@link String} is a MongoDB keyword. The default implementation will check against the
 	 * set of registered keywords returned by {@link #getKeywords()}.
-	 * 
+	 *
 	 * @param candidate
 	 * @return
 	 */
@@ -598,7 +598,7 @@ public class QueryMapper {
 
 	/**
 	 * Value object to capture a query keyword representation.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 */
 	static class Keyword {
@@ -624,7 +624,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns whether the current keyword is the {@code $exists} keyword.
-		 * 
+		 *
 		 * @return
 		 */
 		public boolean isExists() {
@@ -637,7 +637,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns whether the current keyword is the {@code $geometry} keyword.
-		 * 
+		 *
 		 * @return
 		 * @since 1.8
 		 */
@@ -646,13 +646,13 @@ public class QueryMapper {
 		}
 
 		/**
-		 * Returns wheter the current keyword indicates a sample object.
-		 * 
+		 * Returns whether the current keyword indicates a {@link Example} object.
+		 *
 		 * @return
 		 * @since 1.8
 		 */
 		public boolean isSample() {
-			return "$sample".equalsIgnoreCase(key);
+			return "$example".equalsIgnoreCase(key);
 		}
 
 		public boolean hasIterableValue() {
@@ -671,7 +671,7 @@ public class QueryMapper {
 
 	/**
 	 * Value object to represent a field and its meta-information.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 */
 	protected static class Field {
@@ -682,7 +682,7 @@ public class QueryMapper {
 
 		/**
 		 * Creates a new {@link DocumentField} without meta-information but the given name.
-		 * 
+		 *
 		 * @param name must not be {@literal null} or empty.
 		 */
 		public Field(String name) {
@@ -693,7 +693,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns a new {@link DocumentField} with the given name.
-		 * 
+		 *
 		 * @param name must not be {@literal null} or empty.
 		 * @return
 		 */
@@ -703,7 +703,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns whether the current field is the id field.
-		 * 
+		 *
 		 * @return
 		 */
 		public boolean isIdField() {
@@ -714,7 +714,7 @@ public class QueryMapper {
 		 * Returns the underlying {@link MongoPersistentProperty} backing the field. For path traversals this will be the
 		 * property that represents the value to handle. This means it'll be the leaf property for plain paths or the
 		 * association property in case we refer to an association somewhere in the path.
-		 * 
+		 *
 		 * @return
 		 */
 		public MongoPersistentProperty getProperty() {
@@ -723,7 +723,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns the {@link MongoPersistentEntity} that field is conatined in.
-		 * 
+		 *
 		 * @return
 		 */
 		public MongoPersistentEntity<?> getPropertyEntity() {
@@ -732,7 +732,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns whether the field represents an association.
-		 * 
+		 *
 		 * @return
 		 */
 		public boolean isAssociation() {
@@ -741,7 +741,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns the key to be used in the mapped document eventually.
-		 * 
+		 *
 		 * @return
 		 */
 		public String getMappedKey() {
@@ -750,7 +750,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns whether the field references an association in case it refers to a nested field.
-		 * 
+		 *
 		 * @return
 		 */
 		public boolean containsAssociation() {
@@ -768,7 +768,7 @@ public class QueryMapper {
 
 	/**
 	 * Extension of {@link DocumentField} to be backed with mapping metadata.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 * @author Thomas Darimont
 	 */
@@ -785,7 +785,7 @@ public class QueryMapper {
 		/**
 		 * Creates a new {@link MetadataBackedField} with the given name, {@link MongoPersistentEntity} and
 		 * {@link MappingContext}.
-		 * 
+		 *
 		 * @param name must not be {@literal null} or empty.
 		 * @param entity must not be {@literal null}.
 		 * @param context must not be {@literal null}.
@@ -798,7 +798,7 @@ public class QueryMapper {
 		/**
 		 * Creates a new {@link MetadataBackedField} with the given name, {@link MongoPersistentEntity} and
 		 * {@link MappingContext} with the given {@link MongoPersistentProperty}.
-		 * 
+		 *
 		 * @param name must not be {@literal null} or empty.
 		 * @param entity must not be {@literal null}.
 		 * @param context must not be {@literal null}.
@@ -841,7 +841,7 @@ public class QueryMapper {
 					.orElseGet(() -> DEFAULT_ID_NAMES.contains(name));
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.core.convert.QueryMapper.Field#getProperty()
 		 */
@@ -850,7 +850,7 @@ public class QueryMapper {
 			return association == null ? property : association.getInverse();
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.core.convert.QueryMapper.Field#getEntity()
 		 */
@@ -860,7 +860,7 @@ public class QueryMapper {
 			return property == null ? null : mappingContext.getPersistentEntity(property).orElse(null);
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.core.convert.QueryMapper.Field#isAssociation()
 		 */
@@ -869,7 +869,7 @@ public class QueryMapper {
 			return association != null;
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.core.convert.QueryMapper.Field#getAssociation()
 		 */
@@ -880,7 +880,7 @@ public class QueryMapper {
 
 		/**
 		 * Finds the association property in the {@link PersistentPropertyPath}.
-		 * 
+		 *
 		 * @return
 		 */
 		private final Association<MongoPersistentProperty> findAssociation() {
@@ -914,7 +914,7 @@ public class QueryMapper {
 
 		/**
 		 * Returns the {@link PersistentPropertyPath} for the given <code>pathExpression</code>.
-		 * 
+		 *
 		 * @param pathExpression
 		 * @return
 		 */
@@ -951,7 +951,7 @@ public class QueryMapper {
 		/**
 		 * Return the {@link Converter} to be used to created the mapped key. Default implementation will use
 		 * {@link PropertyToFieldNameConverter}.
-		 * 
+		 *
 		 * @return
 		 */
 		protected Converter<MongoPersistentProperty, String> getPropertyConverter() {
@@ -961,7 +961,7 @@ public class QueryMapper {
 		/**
 		 * Return the {@link Converter} to use for creating the mapped key of an association. Default implementation is
 		 * {@link AssociationConverter}.
-		 * 
+		 *
 		 * @return
 		 * @since 1.7
 		 */
@@ -991,7 +991,7 @@ public class QueryMapper {
 			}
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.data.mongodb.core.convert.QueryMapper.Field#getTypeHint()
 		 */
@@ -1028,7 +1028,7 @@ public class QueryMapper {
 
 			/**
 			 * Maps the property name while retaining potential positional operator {@literal $}.
-			 * 
+			 *
 			 * @param property
 			 * @return
 			 */
@@ -1070,7 +1070,7 @@ public class QueryMapper {
 
 	/**
 	 * Converter to skip all properties after an association property was rendered.
-	 * 
+	 *
 	 * @author Oliver Gierke
 	 */
 	protected static class AssociationConverter implements Converter<MongoPersistentProperty, String> {
@@ -1080,7 +1080,7 @@ public class QueryMapper {
 
 		/**
 		 * Creates a new {@link AssociationConverter} for the given {@link Association}.
-		 * 
+		 *
 		 * @param association must not be {@literal null}.
 		 */
 		public AssociationConverter(Association<MongoPersistentProperty> association) {
@@ -1089,7 +1089,7 @@ public class QueryMapper {
 			this.property = association.getInverse();
 		}
 
-		/* 
+		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
 		 */

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Criteria.java

@@ -45,7 +45,7 @@ import com.mongodb.BasicDBList;
 /**
  * Central class for creating queries. It follows a fluent API style so that you can easily chain together multiple
  * criteria. Static import of the 'Criteria.where' method will improve readability.
- * 
+ *
  * @author Thomas Risberg
  * @author Oliver Gierke
  * @author Thomas Darimont
@@ -82,7 +82,7 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Static factory method to create a Criteria using the provided key
-	 * 
+	 *
 	 * @param key
 	 * @return
 	 */
@@ -92,7 +92,7 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Static factory method to create a {@link Criteria} matching an example object.
-	 * 
+	 *
 	 * @param example must not be {@literal null}.
 	 * @return
 	 * @see Criteria#alike(Example)
@@ -104,7 +104,7 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Static factory method to create a {@link Criteria} matching an example object.
-	 * 
+	 *
 	 * @param example must not be {@literal null}.
 	 * @return
 	 * @see Criteria#alike(Example)
@@ -116,7 +116,7 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Static factory method to create a Criteria using the provided key
-	 * 
+	 *
 	 * @return
 	 */
 	public Criteria and(String key) {
@@ -125,7 +125,7 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Creates a criterion using equality
-	 * 
+	 *
 	 * @param o
 	 * @return
 	 */
@@ -381,7 +381,7 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Syntactical sugar for {@link #is(Object)} making obvious that we create a regex predicate.
-	 * 
+	 *
 	 * @param pattern
 	 * @return
 	 */
@@ -420,8 +420,10 @@ public class Criteria implements CriteriaDefinition {
 	 *
 	 * @param circle must not be {@literal null}
 	 * @return
-	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/geoWithin/">MongoDB Query operator: $geoWithin</a>
-	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/centerSphere/">MongoDB Query operator: $centerSphere</a>
+	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/geoWithin/">MongoDB Query operator:
+	 *      $geoWithin</a>
+	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/centerSphere/">MongoDB Query operator:
+	 *      $centerSphere</a>
 	 */
 	public Criteria withinSphere(Circle circle) {
 
@@ -436,7 +438,8 @@ public class Criteria implements CriteriaDefinition {
 	 *
 	 * @param shape
 	 * @return
-	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/geoWithin/">MongoDB Query operator: $geoWithin</a>
+	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/geoWithin/">MongoDB Query operator:
+	 *      $geoWithin</a>
 	 */
 	public Criteria within(Shape shape) {
 
@@ -467,7 +470,8 @@ public class Criteria implements CriteriaDefinition {
 	 *
 	 * @param point must not be {@literal null}
 	 * @return
-	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/nearSphere/">MongoDB Query operator: $nearSphere</a>
+	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/nearSphere/">MongoDB Query operator:
+	 *      $nearSphere</a>
 	 */
 	public Criteria nearSphere(Point point) {
 
@@ -480,7 +484,7 @@ public class Criteria implements CriteriaDefinition {
 	/**
 	 * Creates criterion using {@code $geoIntersects} operator which matches intersections of the given {@code geoJson}
 	 * structure and the documents one. Requires MongoDB 2.4 or better.
-	 * 
+	 *
 	 * @param geoJson must not be {@literal null}.
 	 * @return
 	 * @since 1.8
@@ -498,7 +502,8 @@ public class Criteria implements CriteriaDefinition {
 	 *
 	 * @param maxDistance
 	 * @return
-	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/maxDistance/">MongoDB Query operator: $maxDistance</a>
+	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/maxDistance/">MongoDB Query operator:
+	 *      $maxDistance</a>
 	 */
 	public Criteria maxDistance(double maxDistance) {
 
@@ -514,7 +519,7 @@ public class Criteria implements CriteriaDefinition {
 	/**
 	 * Creates a geospatial criterion using a {@literal $minDistance} operation, for use with {@literal $near} or
 	 * {@literal $nearSphere}.
-	 * 
+	 *
 	 * @param minDistance
 	 * @return
 	 * @since 1.7
@@ -535,7 +540,8 @@ public class Criteria implements CriteriaDefinition {
 	 *
 	 * @param c
 	 * @return
-	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/elemMatch/">MongoDB Query operator: $elemMatch</a>
+	 * @see <a href="https://docs.mongodb.com/manual/reference/operator/query/elemMatch/">MongoDB Query operator:
+	 *      $elemMatch</a>
 	 */
 	public Criteria elemMatch(Criteria c) {
 		criteria.put("$elemMatch", c.getCriteriaObject());
@@ -544,14 +550,14 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Creates a criterion using the given object as a pattern.
-	 * 
+	 *
 	 * @param sample
 	 * @return
 	 * @since 1.8
 	 */
 	public Criteria alike(Example<?> sample) {
 
-		criteria.put("$sample", sample);
+		criteria.put("$example", sample);
 		this.criteriaChain.add(this);
 		return this;
 	}
@@ -561,7 +567,7 @@ public class Criteria implements CriteriaDefinition {
 	 * <p>
 	 * Note that mongodb doesn't support an $or operator to be wrapped in a $not operator.
 	 * <p>
-	 * 
+	 *
 	 * @throws IllegalArgumentException if {@link #orOperator(Criteria...)} follows a not() call directly.
 	 * @param criteria
 	 */
@@ -575,7 +581,7 @@ public class Criteria implements CriteriaDefinition {
 	 * <p>
 	 * Note that mongodb doesn't support an $nor operator to be wrapped in a $not operator.
 	 * <p>
-	 * 
+	 *
 	 * @throws IllegalArgumentException if {@link #norOperator(Criteria...)} follows a not() call directly.
 	 * @param criteria
 	 */
@@ -589,7 +595,7 @@ public class Criteria implements CriteriaDefinition {
 	 * <p>
 	 * Note that mongodb doesn't support an $and operator to be wrapped in a $not operator.
 	 * <p>
-	 * 
+	 *
 	 * @throws IllegalArgumentException if {@link #andOperator(Criteria...)} follows a not() call directly.
 	 * @param criteria
 	 */
@@ -771,7 +777,7 @@ public class Criteria implements CriteriaDefinition {
 
 	/**
 	 * Checks the given objects for equality. Handles {@link Pattern} and arrays correctly.
-	 * 
+	 *
 	 * @param left
 	 * @param right
 	 * @return

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/AggregationTests.java

@@ -1612,6 +1612,24 @@ public class AggregationTests {
 				skip(100L));
 	}
 
+	@Test // DATAMONGO-1325
+	public void shouldApplySampleCorrectly() {
+
+		assumeTrue(mongoVersion.isGreaterThanOrEqualTo(THREE_DOT_TWO));
+
+		createUserWithLikesDocuments();
+
+		TypedAggregation<UserWithLikes> agg = newAggregation(UserWithLikes.class, //
+				unwind("likes"), //
+				sample(3) //
+		);
+
+		assertThat(agg.toString(), is(notNullValue()));
+
+		AggregationResults<LikeStats> result = mongoTemplate.aggregate(agg, LikeStats.class);
+		assertThat(result.getMappedResults().size(), is(3));
+	}
+
 	@Test // DATAMONGO-1457
 	public void sliceShouldBeAppliedCorrectly() {
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/aggregation/SampleOperationUnitTests.java

@@ -31,24 +31,29 @@ public class SampleOperationUnitTests {
 	private static final String SIZE = "size";
 	private static final String OP = "$sample";
 
-	@Test(expected = IllegalArgumentException.class)
+	@Test(expected = IllegalArgumentException.class) // DATAMONGO-1325
 	public void rejectsNegativeSample() {
 		new SampleOperation(-1L);
 	}
 
-	@Test(expected = IllegalArgumentException.class)
+	@Test(expected = IllegalArgumentException.class) // DATAMONGO-1325
 	public void rejectsZeroSample() {
 		new SampleOperation(0L);
 	}
 
-	@Test
+	@Test // DATAMONGO-1325
 	public void rendersSampleOperation() {
+
 		long sampleSize = 5L;
+
 		SampleOperation sampleOperation = Aggregation.sample(sampleSize);
+
 		Document sampleOperationDocument = sampleOperation.toDocument(Aggregation.DEFAULT_CONTEXT);
+
 		assertNotNull(sampleOperationDocument.get(OP));
 		assertThat(sampleOperationDocument.get(OP), is(instanceOf(Document.class)));
-		Document sampleSizeDocument =  sampleOperationDocument.get(OP, Document.class);
+
+		Document sampleSizeDocument = sampleOperationDocument.get(OP, Document.class);
 		assertEquals(sampleSize, sampleSizeDocument.get(SIZE));
 	}
 }