DATAMONGO-943 - Add support for $position to Update $push $each.

We now support $position on update.push.

Original pull request: #248.

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

@@ -163,7 +163,8 @@ public class Update {
 
 	/**
 	 * Update using {@code $push} modifier. <br/>
-	 * Allows creation of {@code $push} command for single or multiple (using {@code $each}) values.
+	 * Allows creation of {@code $push} command for single or multiple (using {@code $each}) values as well as using
+	 * {@code $position}.
 	 * 
 	 * @see http://docs.mongodb.org/manual/reference/operator/update/push/
 	 * @see http://docs.mongodb.org/manual/reference/operator/update/each/
@@ -577,6 +578,31 @@ public class Update {
 		}
 	}
 
+	/**
+	 * {@link Modifier} implementation used to propagate {@code $position}.
+	 * 
+	 * @author Christoph Strobl
+	 * @since 1.7
+	 */
+	private static class PositionModifier implements Modifier {
+
+		private final int position;
+
+		public PositionModifier(int position) {
+			this.position = position;
+		}
+
+		@Override
+		public String getKey() {
+			return "$position";
+		}
+
+		@Override
+		public Object getValue() {
+			return position;
+		}
+	}
+
 	/**
 	 * Builder for creating {@code $push} modifiers
 	 * 
@@ -605,6 +631,42 @@ public class Update {
 			return Update.this.push(key, this.modifiers);
 		}
 
+		/**
+		 * Forces values to be added at the given {@literal position}.
+		 * 
+		 * @param position needs to be greater than or equal to zero.
+		 * @return
+		 * @since 1.7
+		 */
+		public PushOperatorBuilder atPosition(int position) {
+
+			if (position < 0) {
+				throw new IllegalArgumentException("Position must be greater than or equal to zero.");
+			}
+
+			this.modifiers.addModifier(new PositionModifier(position));
+
+			return this;
+		}
+
+		/**
+		 * Forces values to be added at given {@literal position}.
+		 * 
+		 * @param position can be {@literal null} which will be appended at the last position.
+		 * @return
+		 * @since 1.7
+		 */
+		public PushOperatorBuilder atPosition(Position position) {
+
+			if (position == null || Position.LAST.equals(position)) {
+				return this;
+			}
+
+			this.modifiers.addModifier(new PositionModifier(0));
+
+			return this;
+		}
+
 		/**
 		 * Propagates {@link #value(Object)} to {@code $push}
 		 * 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/convert/UpdateMapperUnitTests.java

@@ -44,6 +44,7 @@ import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
 import org.springframework.data.mongodb.core.query.Criteria;
 import org.springframework.data.mongodb.core.query.Query;
 import org.springframework.data.mongodb.core.query.Update;
+import org.springframework.data.mongodb.core.query.Update.Position;
 
 import com.mongodb.BasicDBList;
 import com.mongodb.BasicDBObject;
@@ -293,6 +294,76 @@ public class UpdateMapperUnitTests {
 		assertThat(getAsDBObject(push, "type").containsField("$each"), is(true));
 	}
 
+	/**
+	 * @see DATAMONGO-943
+	 */
+	@Test
+	public void updatePushEachAtPositionWorksCorrectlyWhenGivenPositiveIndexParameter() {
+
+		Update update = new Update().push("key").atPosition(2).each(Arrays.asList("Arya", "Arry", "Weasel"));
+
+		DBObject mappedObject = mapper.getMappedObject(update.getUpdateObject(), context.getPersistentEntity(Object.class));
+
+		DBObject push = getAsDBObject(mappedObject, "$push");
+		DBObject key = getAsDBObject(push, "key");
+
+		assertThat(key.containsField("$position"), is(true));
+		assertThat((Integer) key.get("$position"), is(2));
+		assertThat(getAsDBObject(push, "key").containsField("$each"), is(true));
+	}
+
+	/**
+	 * @see DATAMONGO-943
+	 */
+	@Test
+	public void updatePushEachAtPositionWorksCorrectlyWhenGivenPositionFirst() {
+
+		Update update = new Update().push("key").atPosition(Position.FIRST).each(Arrays.asList("Arya", "Arry", "Weasel"));
+
+		DBObject mappedObject = mapper.getMappedObject(update.getUpdateObject(), context.getPersistentEntity(Object.class));
+
+		DBObject push = getAsDBObject(mappedObject, "$push");
+		DBObject key = getAsDBObject(push, "key");
+
+		assertThat(key.containsField("$position"), is(true));
+		assertThat((Integer) key.get("$position"), is(0));
+		assertThat(getAsDBObject(push, "key").containsField("$each"), is(true));
+	}
+
+	/**
+	 * @see DATAMONGO-943
+	 */
+	@Test
+	public void updatePushEachAtPositionWorksCorrectlyWhenGivenPositionLast() {
+
+		Update update = new Update().push("key").atPosition(Position.LAST).each(Arrays.asList("Arya", "Arry", "Weasel"));
+
+		DBObject mappedObject = mapper.getMappedObject(update.getUpdateObject(), context.getPersistentEntity(Object.class));
+
+		DBObject push = getAsDBObject(mappedObject, "$push");
+		DBObject key = getAsDBObject(push, "key");
+
+		assertThat(key.containsField("$position"), is(false));
+		assertThat(getAsDBObject(push, "key").containsField("$each"), is(true));
+	}
+
+	/**
+	 * @see DATAMONGO-943
+	 */
+	@Test
+	public void updatePushEachAtPositionWorksCorrectlyWhenGivenPositionNull() {
+
+		Update update = new Update().push("key").atPosition(null).each(Arrays.asList("Arya", "Arry", "Weasel"));
+
+		DBObject mappedObject = mapper.getMappedObject(update.getUpdateObject(), context.getPersistentEntity(Object.class));
+
+		DBObject push = getAsDBObject(mappedObject, "$push");
+		DBObject key = getAsDBObject(push, "key");
+
+		assertThat(key.containsField("$position"), is(false));
+		assertThat(getAsDBObject(push, "key").containsField("$each"), is(true));
+	}
+
 	/**
 	 * @see DATAMONGO-410
 	 */

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/query/UpdateTests.java

@@ -476,4 +476,12 @@ public class UpdateTests {
 		assertThat(update.getUpdateObject(),
 				equalTo(new BasicDBObjectBuilder().add("$bit", new BasicDBObject("key", new BasicDBObject("xor", 10L))).get()));
 	}
+
+	/**
+	 * @see DATAMONGO-943
+	 */
+	@Test(expected = IllegalArgumentException.class)
+	public void pushShouldThrowExceptionWhenGivenNegativePosition() {
+		new Update().push("foo").atPosition(-1).each("booh");
+	}
 }