CSHARP-1246: fixed issue where expressions including variables were not partially evaluated in a FieldDefinition.

Author: craiggwilson

src/MongoDB.Driver.Tests/UpdateDefinitionBuilderTests.cs

@@ -236,6 +236,11 @@ public void Indexed_Typed()
             Assert(subject.Set(x => x.FavoriteColors[2], "yellow"), "{$set: {'colors.2': 'yellow'}}");
             Assert(subject.Set(x => x.Pets[2].Name, "Fluffencutters"), "{$set: {'pets.2.name': 'Fluffencutters'}}");
             Assert(subject.Set(x => x.Pets.ElementAt(2).Name, "Fluffencutters"), "{$set: {'pets.2.name': 'Fluffencutters'}}");
+
+            var index = 2;
+            Assert(subject.Set(x => x.FavoriteColors[index], "yellow"), "{$set: {'colors.2': 'yellow'}}");
+            Assert(subject.Set(x => x.Pets[index].Name, "Fluffencutters"), "{$set: {'pets.2.name': 'Fluffencutters'}}");
+            Assert(subject.Set(x => x.Pets.ElementAt(index).Name, "Fluffencutters"), "{$set: {'pets.2.name': 'Fluffencutters'}}");
         }
 
         [Test]

src/MongoDB.Driver/FieldDefinition.cs

@@ -200,11 +200,12 @@ public LambdaExpression Expression
         /// <inheritdoc />
         public override RenderedFieldDefinition Render(IBsonSerializer<TDocument> documentSerializer, IBsonSerializerRegistry serializerRegistry)
         {
+            var lambda = (LambdaExpression)PartialEvaluator.Evaluate(_expression);
             var binder = new SerializationInfoBinder(serializerRegistry);
             var parameterSerializationInfo = new BsonSerializationInfo(null, documentSerializer, documentSerializer.ValueType);
-            var parameterExpression = new SerializationExpression(_expression.Parameters[0], parameterSerializationInfo);
-            binder.RegisterParameterReplacement(_expression.Parameters[0], parameterExpression);
-            var bound = binder.Bind(_expression.Body) as ISerializationExpression;
+            var parameterExpression = new SerializationExpression(lambda.Parameters[0], parameterSerializationInfo);
+            binder.RegisterParameterReplacement(lambda.Parameters[0], parameterExpression);
+            var bound = binder.Bind(lambda.Body) as ISerializationExpression;
             if (bound == null)
             {
                 var message = string.Format("Unable to determine the serialization information for {0}.", _expression);
@@ -244,11 +245,12 @@ public Expression<Func<TDocument, TField>> Expression
         /// <inheritdoc />
         public override RenderedFieldDefinition<TField> Render(IBsonSerializer<TDocument> documentSerializer, IBsonSerializerRegistry serializerRegistry)
         {
+            var lambda = (LambdaExpression)PartialEvaluator.Evaluate(_expression);
             var binder = new SerializationInfoBinder(serializerRegistry);
             var parameterSerializationInfo = new BsonSerializationInfo(null, documentSerializer, documentSerializer.ValueType);
-            var parameterExpression = new SerializationExpression(_expression.Parameters[0], parameterSerializationInfo);
-            binder.RegisterParameterReplacement(_expression.Parameters[0], parameterExpression);
-            var bound = binder.Bind(_expression.Body) as ISerializationExpression;
+            var parameterExpression = new SerializationExpression(lambda.Parameters[0], parameterSerializationInfo);
+            binder.RegisterParameterReplacement(lambda.Parameters[0], parameterExpression);
+            var bound = binder.Bind(lambda.Body) as ISerializationExpression;
             if (bound == null)
             {
                 var message = string.Format("Unable to determine the serialization information for {0}.", _expression);