Added Replace method to Update<TDocument>.

Author: rstam

Driver/Builders/UpdateBuilder.cs

@@ -1457,6 +1457,17 @@ public static UpdateBuilder<TDocument> PushAll<TValue>(Expression<Func<TDocument
             return new UpdateBuilder<TDocument>().PushAll(memberExpression, values);
         }
 
+        /// <summary>
+        /// Replaces the entire document with a new document (the _id must remain the same).
+        /// </summary>
+        /// <param name="document">The replacement document.</param>
+        /// <returns>An UpdateWrapper.</returns>
+        public static IMongoUpdate Replace(TDocument document)
+        {
+            if (document == null) { throw new ArgumentNullException("document"); }
+            return UpdateWrapper.Create<TDocument>(document);
+        }
+
         /// <summary>
         /// Sets the value of the named element to a new value (see $set).
         /// </summary>

DriverUnitTests/Builders/UpdateBuilderTests.cs

@@ -31,6 +31,8 @@ public class UpdateBuilderTests
     {
         private class Test
         {
+            public int Id = 0;
+
             [BsonElement("x")]
             public int X = 0;
 
@@ -416,6 +418,24 @@ public void TestPushAllWrapped()
             Assert.AreEqual(expected, update.ToJson());
         }
 
+        [Test]
+        public void TestReplace()
+        {
+            var t = new Test { Id = 1, X = 2, Y = null, B = null };
+            var update = Update.Replace(t);
+            var expected = "{ \"_id\" : 1, \"x\" : 2, \"y\" : null, \"b\" : null }";
+            Assert.AreEqual(expected, update.ToJson());
+        }
+
+        [Test]
+        public void TestReplace_Typed()
+        {
+            var t = new Test { Id = 1, X = 2, Y = null, B = null };
+            var update = Update<Test>.Replace(t);
+            var expected = "{ \"_id\" : 1, \"x\" : 2, \"y\" : null, \"b\" : null }";
+            Assert.AreEqual(expected, update.ToJson());
+        }
+
         [Test]
         public void TestSet()
         {