Fix #1317: FieldValues shouldn't throw when no values are present

Author: gmarz

src/Nest/Domain/Paths/FieldSelection.cs

@@ -70,8 +70,9 @@ public K[] FieldValues<K>(Expression<Func<T, K>> objectPath)
 		/// <typeparam name="K">The type to return the value as, remember that if your field is a string K should be string[]</typeparam>
 		private K FieldArray<K>(string path)
 		{
+			var fieldValues = ((IFieldSelection<T>)this).FieldValuesDictionary;
 			object o;
-			if (((IFieldSelection<T>)this).FieldValuesDictionary.TryGetValue(path, out o))
+			if (fieldValues != null && fieldValues.TryGetValue(path, out o))
 			{
 				var t = typeof(K);
 				if (o is JArray && t.GetInterfaces().Contains(typeof(IEnumerable)))

src/Tests/Nest.Tests.Integration/Nest.Tests.Integration.csproj

@@ -174,6 +174,7 @@
     <Compile Include="Reproduce\Reproduce1236Tests.cs" />
     <Compile Include="Reproduce\Reproduce1278Tests.cs" />
     <Compile Include="Reproduce\Reproduce1304Tests.cs" />
+    <Compile Include="Reproduce\Reproduce1317Tests.cs" />
     <Compile Include="Reproduce\Reproduce769Tests.cs" />
     <Compile Include="Reproduce\Reproduce945Tests.cs" />
     <Compile Include="Reproduce\Reproduce953Tests.cs" />

src/Tests/Nest.Tests.Integration/Reproduce/Reproduce1317Tests.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using FluentAssertions;
+using NUnit.Framework;
+using Nest.Tests.MockData.Domain;
+
+namespace Nest.Tests.Integration.Reproduce
+{
+	[TestFixture]
+	public class Reproduce1317Tests : IntegrationTests
+	{
+		[Test]
+		public void FieldValuesShouldNotThrowOnNonExistentFields()
+		{
+			// With no field values returned
+			var result = this.Client.Get<ElasticsearchProject>(g => g
+				.Id(4)
+				.Fields("fieldthatdoesntexist")
+			);
+
+			result.Fields.FieldValues<string[]>("fieldthatdoesntexist").Should().BeNull();
+
+			// With field values returned
+			result = this.Client.Get<ElasticsearchProject>(g => g
+				.Id(4)
+				.Fields("fieldthatdoesntexist", "name")
+			);
+
+			result.Fields.FieldValues<string[]>("name").Count().Should().BeGreaterThan(0);
+			result.Fields.FieldValues<string[]>("fieldthatdoesntexist").Should().BeNull();
+		}
+	}
+}