CSHARP-4562: Use PartialEvaluator when translating an Expression to a field.

Author: rstam

src/MongoDB.Driver/Linq/Linq3Implementation/LinqProviderAdapterV3.cs

@@ -79,6 +79,7 @@ internal override RenderedFieldDefinition TranslateExpressionToField<TDocument>(
             IBsonSerializer<TDocument> documentSerializer,
             IBsonSerializerRegistry serializerRegistry)
         {
+            expression = (LambdaExpression)PartialEvaluator.EvaluatePartially(expression);
             var parameter = expression.Parameters.Single();
             var context = TranslationContext.Create(expression, documentSerializer);
             var symbol = context.CreateSymbol(parameter, documentSerializer, isCurrent: true);

tests/MongoDB.Driver.Tests/Linq/Linq3ImplementationTests/Jira/CSharp4562Tests.cs

@@ -0,0 +1,76 @@
+/* Copyright 2010-present MongoDB Inc.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System.Collections.Generic;
+using MongoDB.Driver.Linq;
+using MongoDB.TestHelpers.XunitExtensions;
+using Xunit;
+
+namespace MongoDB.Driver.Tests.Linq.Linq3ImplementationTests.Jira
+{
+    public class CSharp4562Tests : Linq3IntegrationTest
+    {
+        [Theory]
+        [ParameterAttributeData]
+        public void SortBy_using_constant_should_work(
+            [Values(LinqProvider.V2, LinqProvider.V3)] LinqProvider linqProvider)
+        {
+            var collection = CreateCollection(linqProvider);
+
+            var aggregate = GetTranslationsSortedByEnglish(collection);
+
+            var stages = Translate(collection, aggregate);
+            AssertStages(stages, "{ $sort : { 'Text.en' : 1 } }");
+        }
+
+        [Theory]
+        [ParameterAttributeData]
+        public void SortBy_using_parameter_should_work(
+            [Values(LinqProvider.V2, LinqProvider.V3)] LinqProvider linqProvider)
+        {
+            var collection = CreateCollection(linqProvider);
+            var language = "sp";
+
+            var aggregate = GetSortedTranslations(collection, language);
+
+            var stages = Translate(collection, aggregate);
+            AssertStages(stages, "{ $sort : { 'Text.sp' : 1 } }");
+        }
+
+        private IMongoCollection<Translation> CreateCollection(LinqProvider linqProvider)
+        {
+            var collection = GetCollection<Translation>("test", linqProvider);
+            return collection;
+        }
+
+        private class Translation
+        {
+            public int Id { get; set; }
+            public Dictionary<string, string> Text { get; set; }
+        }
+
+        private static IAggregateFluent<Translation> GetSortedTranslations(IMongoCollection<Translation> collection, string language)
+        {
+            return collection.Aggregate()
+                .SortBy(c => c.Text[language]);
+        }
+
+        private static IAggregateFluent<Translation> GetTranslationsSortedByEnglish(IMongoCollection<Translation> collection)
+        {
+            return collection.Aggregate()
+                .SortBy(c => c.Text["en"]);
+        }
+    }
+}