From 5965fb368268c1d8a6d629e222062e00d79a25f3 Mon Sep 17 00:00:00 2001
From: Jared Nance <jaredcnance@gmail.com>
Date: Mon, 3 Sep 2018 21:21:23 -0700
Subject: [PATCH] fix(Identifiable): handle null id values

---
 src/JsonApiDotNetCore/Models/Identifiable.cs |  3 +++
 test/UnitTests/Models/IdentifiableTests.cs   | 12 +++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/JsonApiDotNetCore/Models/Identifiable.cs b/src/JsonApiDotNetCore/Models/Identifiable.cs
index 08dd43bf22..038544a89c 100644
--- a/src/JsonApiDotNetCore/Models/Identifiable.cs
+++ b/src/JsonApiDotNetCore/Models/Identifiable.cs
@@ -37,6 +37,9 @@ public string StringId
         /// </summary>
         protected virtual string GetStringId(object value)
         {
+            if(value == null)
+                return string.Empty;
+
             var type = typeof(T);
             var stringValue = value.ToString();
 
diff --git a/test/UnitTests/Models/IdentifiableTests.cs b/test/UnitTests/Models/IdentifiableTests.cs
index 778b1b485f..da4e30360a 100644
--- a/test/UnitTests/Models/IdentifiableTests.cs
+++ b/test/UnitTests/Models/IdentifiableTests.cs
@@ -21,6 +21,16 @@ public void Setting_StringId_To_Null_Sets_Id_As_Default()
             Assert.Equal(0, resource.Id);
         }
 
-        private class IntId : Identifiable { }
+        [Fact]
+        public void GetStringId_Returns_EmptyString_If_Object_Is_Null()
+        {
+            var resource = new IntId();
+            var stringId = resource.ExposedGetStringId(null);
+            Assert.Equal(string.Empty, stringId);
+        }
+
+        private class IntId : Identifiable { 
+            public string ExposedGetStringId(object value) => GetStringId(value);
+        }
     }
 }