Align JsonInheritanceConverterAttribute in Liquid template, RicoSuter…

…/NSwag#4375
RicoSuter · Nov 19, 2024 · 22d33c9 · 22d33c9
1 parent 9c627bf
commit 22d33c9
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Showing 3 changed files with 44 additions and 22 deletions.
diff --git a/src/NJsonSchema.CodeGeneration.CSharp/Templates/JsonInheritanceConverter.liquid b/src/NJsonSchema.CodeGeneration.CSharp/Templates/JsonInheritanceConverter.liquid
@@ -45,17 +45,24 @@ public class JsonInheritanceConverter<TBase> : System.Text.Json.Serialization.Js
 
     public override void Write(System.Text.Json.Utf8JsonWriter writer, TBase value, System.Text.Json.JsonSerializerOptions options)
     {
-        writer.WriteStartObject();
-        writer.WriteString(_discriminatorName, GetDiscriminatorValue(value.GetType()));
+        if (value != null)
+        {
+            writer.WriteStartObject();
+            writer.WriteString(_discriminatorName, GetDiscriminatorValue(value.GetType()));
+
+            var bytes = System.Text.Json.JsonSerializer.SerializeToUtf8Bytes((object)value, options);
+            var document = System.Text.Json.JsonDocument.Parse(bytes);
+            foreach (var property in document.RootElement.EnumerateObject())
+            {
+                property.WriteTo(writer);
+            }
 
-        var bytes = System.Text.Json.JsonSerializer.SerializeToUtf8Bytes((object)value, options);
-        var document = System.Text.Json.JsonDocument.Parse(bytes);
-        foreach (var property in document.RootElement.EnumerateObject())
+            writer.WriteEndObject();
+        }
+        else
         {
-            property.WriteTo(writer);
+            writer.WriteNullValue();
         }
-
-        writer.WriteEndObject();
     }
 
     public string GetDiscriminatorValue(System.Type type)
@@ -71,22 +78,25 @@ public class JsonInheritanceConverter<TBase> : System.Text.Json.Serialization.Js
 
     protected System.Type GetDiscriminatorType(System.Text.Json.JsonElement jObject, System.Type objectType, string discriminatorValue)
     {
-        var jsonInheritanceAttributeSubtype = GetObjectSubtype(objectType, discriminatorValue);
-        if (jsonInheritanceAttributeSubtype != null)
+        if (discriminatorValue != null)
         {
-            return jsonInheritanceAttributeSubtype;
-        }
+            var jsonInheritanceAttributeSubtype = GetObjectSubtype(objectType, discriminatorValue);
+            if (jsonInheritanceAttributeSubtype != null)
+            {
+                return jsonInheritanceAttributeSubtype;
+            }
 
-        if (objectType.Name == discriminatorValue)
-        {
-            return objectType;
-        }
+            if (objectType.Name == discriminatorValue)
+            {
+                return objectType;
+            }
 
-        var typeName = objectType.Namespace + "." + discriminatorValue;
-        var subtype = System.Reflection.IntrospectionExtensions.GetTypeInfo(objectType).Assembly.GetType(typeName);
-        if (subtype != null)
-        {
-            return subtype;
+            var typeName = objectType.Namespace + "." + discriminatorValue;
+            var subtype = System.Reflection.IntrospectionExtensions.GetTypeInfo(objectType).Assembly.GetType(typeName);
+            if (subtype != null)
+            {
+                return subtype;
+            }
         }
 
         throw new System.InvalidOperationException("Could not find subtype of '" + objectType.Name + "' with discriminator '" + discriminatorValue + "'.");

diff --git a/src/NJsonSchema.Tests/Generation/SystemTextJson/SystemTextJsonInheritanceTests.cs b/src/NJsonSchema.Tests/Generation/SystemTextJson/SystemTextJsonInheritanceTests.cs
@@ -1,4 +1,6 @@
 using NJsonSchema.Converters;
+using System;
+using System.Text.Json;
 using System.Text.Json.Serialization;
 using System.Threading.Tasks;
 using Xunit;
@@ -63,6 +65,16 @@ public async Task When_using_JsonInheritanceAttribute_and_SystemTextJson_then_sc
                     """.ReplaceLineEndings(), data);
         }
 
+        [Fact]
+        public async Task When_discriminator_is_wrong_then_no_stackoverflow()
+        {
+            //// Act & Assert
+            Assert.Throws<InvalidOperationException>(() => // Throws "Could not find subtype of..."
+            {
+                JsonSerializer.Deserialize<Fruit>("{\"k\": \"invalid\"}");
+            });            
+        }
+
 #if !NETFRAMEWORK
 
         public class Apple2 : Fruit2

diff --git a/src/NJsonSchema/Converters/JsonInheritanceConverter.cs b/src/NJsonSchema/Converters/JsonInheritanceConverter.cs
@@ -85,7 +85,7 @@ public JsonInheritanceConverter(string discriminatorName)
         /// <inheritdoc />
         public override void Write(Utf8JsonWriter writer, TBase? value, JsonSerializerOptions options)
         {
-            if (value is not null)
+            if (value != null)
             {
                 writer.WriteStartObject();
                 writer.WriteString(_discriminatorName, GetDiscriminatorValue(value.GetType()));