From f2a312992107006557e81bd46d25d57812932282 Mon Sep 17 00:00:00 2001
From: Ken Dale <ken@kendaleiv.com>
Date: Tue, 25 Sep 2018 08:57:44 -0400
Subject: [PATCH] Fix NullReferenceException when null value in string array
 filter

---
 src/Filter.Nest/FilterLogic.cs                |  6 ++++--
 ...QueryContainerDescriptorExtensionsTests.cs | 20 +++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/Filter.Nest/FilterLogic.cs b/src/Filter.Nest/FilterLogic.cs
index abcfa2a..7f11907 100644
--- a/src/Filter.Nest/FilterLogic.cs
+++ b/src/Filter.Nest/FilterLogic.cs
@@ -138,12 +138,14 @@ internal static List<Func<QueryContainerDescriptor<T>, QueryContainer>> Generate
                             throw new InvalidOperationException($"NEST filtering does not work on `Range<T>` where `T` is `{filterProperty.PropertyType.Name}`.");
                         }
                     }
-                    else
-                    if (typeof(IEnumerable).IsAssignableFrom(filterProperty.PropertyType)
+                    else if (typeof(IEnumerable).IsAssignableFrom(filterProperty.PropertyType)
                         && filterProperty.PropertyType != typeof(string))
                     {
                         foreach (var item in (IEnumerable)filterPropertyValue)
                         {
+                            if (item == null)
+                                continue;
+
                             if (aliasAttribute != null)
                             {
                                 queries.Add(x =>
diff --git a/tests/Filter.Nest.Tests/QueryContainerDescriptorExtensionsTests.cs b/tests/Filter.Nest.Tests/QueryContainerDescriptorExtensionsTests.cs
index 04248ce..2cc6090 100644
--- a/tests/Filter.Nest.Tests/QueryContainerDescriptorExtensionsTests.cs
+++ b/tests/Filter.Nest.Tests/QueryContainerDescriptorExtensionsTests.cs
@@ -99,6 +99,26 @@ public void Multiple_filter_properties_queried_as_collection_of_and_operators()
                 }
             }
 
+            [Fact]
+            public void Null_string_array_item_does_not_throw_NullReferenceException()
+            {
+                using (var elasticsearch = new ElasticsearchInside.Elasticsearch())
+                {
+                    var elasticClient = new ElasticClient(new ConnectionSettings(elasticsearch.Url));
+
+                    var camaro = new Car { Name = "Camaro", IsElectric = false };
+                    var volt = new Car { Name = "Volt", IsElectric = true };
+
+                    elasticClient.Index(camaro, x => x.Index("vehicles"));
+                    elasticClient.Index(volt, x => x.Index("vehicles"));
+
+                    elasticClient.Refresh("vehicles");
+
+                    elasticClient.Search<Car>(s => s.Index("vehicles").Query(
+                        q => q.MatchAll() && q.Filter(new { Name = new string[] { null } })));
+                }
+            }
+
             [Fact]
             public void Nullable_boolean_omitted_returns_expected_results()
             {