Merge pull request #103 from manuc66/bugfix/Multiple_type_discriminat…

…ors_in_JSON_silently_passes._#100 Multiple type discriminators in JSON silently passes. #100
manuc66 · Jun 16, 2020 · 239eadf · 239eadf
2 parents b8cfd60 + 42b7844
commit 239eadf
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Showing 2 changed files with 20 additions and 3 deletions.
diff --git a/JsonSubTypes.Tests/DemoKnownSubTypeWithProperty.cs b/JsonSubTypes.Tests/DemoKnownSubTypeWithProperty.cs
@@ -61,5 +61,14 @@ public void FallBackToPArentWhenNotFound()
             var persons = JsonConvert.DeserializeObject<ICollection<Person>>(json);
             Assert.AreEqual(typeof(Person), persons.First().GetType());
         }
+
+        [Test]
+        public void ThrowIfManyMatches()
+        {
+            string json = "{\r\n  \"Name\": \"Foo\",\r\n  \"Skill\": \"A\",\r\n  \"JobTitle\": \"B\"\r\n}";
+
+            var jsonSerializationException = Assert.Throws<JsonSerializationException>(() => JsonConvert.DeserializeObject<Person>(json));
+            Assert.AreEqual("Ambiguous type resolution, expected only one type but got: JsonSubTypes.Tests.DemoKnownSubTypeWithProperty+Employee, JsonSubTypes.Tests.DemoKnownSubTypeWithProperty+Artist", jsonSerializationException.Message);
+        }
     }
-}
+}
diff --git a/JsonSubTypes/JsonSubtypes.cs b/JsonSubTypes/JsonSubtypes.cs
@@ -281,7 +281,7 @@ private Type GetTypeByPropertyPresence(JObject jObject, Type parentType)
         {
             var knownSubTypeAttributes = GetTypesByPropertyPresence(parentType);
 
-            return knownSubTypeAttributes
+            var types = knownSubTypeAttributes
                 .Select(knownType =>
                 {
                     if (TryGetValueInJson(jObject, knownType.Key, out JToken _))
@@ -295,7 +295,15 @@ private Type GetTypeByPropertyPresence(JObject jObject, Type parentType)
 
                     return null;
                 })
-                .FirstOrDefault(type => type != null);
+                .Where(type => type != null)
+                .ToArray();
+
+            if (types.Length == 1)
+            {
+                return types[0];
+            }
+
+            throw new JsonSerializationException("Ambiguous type resolution, expected only one type but got: " + String.Join(", ", types.Select(t => t.FullName).ToArray()));
         }
 
         internal virtual Dictionary<string, Type> GetTypesByPropertyPresence(Type parentType)