Add support for STJ-native inheritance schema generation, #1595

RicoSuter · Sep 26, 2023 · 16bc1c0 · 16bc1c0
1 parent e12442b
commit 16bc1c0
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Showing 5 changed files with 96 additions and 11 deletions.
diff --git a/global.json b/global.json
diff --git a/src/NJsonSchema.Tests/Generation/SystemTextJson/SystemTextJsonInheritanceTests.cs b/src/NJsonSchema.Tests/Generation/SystemTextJson/SystemTextJsonInheritanceTests.cs
@@ -1,4 +1,5 @@
 using NJsonSchema.Converters;
+using System.Text.Json.Serialization;
 using System.Threading.Tasks;
 using Xunit;
 
@@ -35,6 +36,55 @@ public async Task When_using_JsonInheritanceAttribute_and_SystemTextJson_then_sc
             Assert.NotNull(data);
             Assert.Contains(@"""a"": """, data);
             Assert.Contains(@"""o"": """, data);
+            Assert.Contains(@"""discriminator"": {
+    ""propertyName"": ""k"",
+    ""mapping"": {
+      ""a"": ""#/definitions/Apple"",
+      ""o"": ""#/definitions/Orange""
+    }
+  },", data);
+        }
+
+#if !NET462
+
+        public class Apple2 : Fruit2
+        {
+            public string Foo { get; set; }
+        }
+
+        public class Orange2 : Fruit2
+        {
+            public string Bar { get; set; }
+        }
+
+        [JsonDerivedType(typeof(Apple2), "a")]
+        [JsonDerivedType(typeof(Orange2), "o")]
+        [JsonPolymorphic(TypeDiscriminatorPropertyName = "k")]
+        public class Fruit2
+        {
+            public string Baz { get; set; }
         }
+
+        [Fact]
+        public async Task When_using_native_attributes_in_SystemTextJson_then_schema_is_correct()
+        {
+            //// Act
+            var schema = JsonSchema.FromType<Fruit2>();
+            var data = schema.ToJson();
+
+            //// Assert
+            Assert.NotNull(data);
+            Assert.Contains(@"""a"": """, data);
+            Assert.Contains(@"""o"": """, data);
+            Assert.Contains(@"""discriminator"": {
+    ""propertyName"": ""k"",
+    ""mapping"": {
+      ""a"": ""#/definitions/Apple2"",
+      ""o"": ""#/definitions/Orange2""
+    }
+  },", data);
+        }
+
+#endif
     }
 }
diff --git a/src/NJsonSchema.Tests/NJsonSchema.Tests.csproj b/src/NJsonSchema.Tests/NJsonSchema.Tests.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net462</TargetFrameworks>
+    <TargetFrameworks>net7.0;net462</TargetFrameworks>
     <IsPackable>false</IsPackable>
     <TreatWarningsAsErrors>false</TreatWarningsAsErrors>
   </PropertyGroup>

diff --git a/src/NJsonSchema/Generation/JsonSchemaGenerator.cs b/src/NJsonSchema/Generation/JsonSchemaGenerator.cs
@@ -917,6 +917,18 @@ private void GenerateKnownTypes(Type type, JsonSchemaResolver schemaResolver)
                     AddKnownType(knownType, schemaResolver);
                 }
             }
+
+            foreach (var jsonConverterAttribute in attributes
+                .GetAssignableToTypeName("System.Text.Json.Serialization.JsonDerivedTypeAttribute", TypeNameStyle.FullName))
+            {
+                var knownType = ObjectExtensions.TryGetPropertyValue<Type>(
+                    jsonConverterAttribute, "DerivedType", null);
+
+                if (knownType != null)
+                {
+                    AddKnownType(knownType, schemaResolver);
+                }
+            }
         }
 
         private void AddKnownType(Type type, JsonSchemaResolver schemaResolver)
@@ -1067,6 +1079,7 @@ private object TryGetInheritanceDiscriminatorConverter(Type type)
         {
             var typeAttributes = type.GetTypeInfo().GetCustomAttributes(false).OfType<Attribute>();
 
+            // support for NJsonSchema provided inheritance converters
             dynamic jsonConverterAttribute = typeAttributes.FirstAssignableToTypeNameOrDefault(nameof(JsonConverterAttribute), TypeNameStyle.Name);
             if (jsonConverterAttribute != null)
             {
@@ -1084,9 +1097,40 @@ private object TryGetInheritanceDiscriminatorConverter(Type type)
                 }
             }
 
+            // support for native System.Text.Json inheritance
+            dynamic[] jsonDerivedTypeAttributes = typeAttributes
+                .Where(a => a.GetType().IsAssignableToTypeName("System.Text.Json.Serialization.JsonDerivedTypeAttribute", TypeNameStyle.FullName))
+                .ToArray();
+
+            if (jsonDerivedTypeAttributes.Any())
+            {
+                dynamic jsonPolymorphicAttribute = typeAttributes
+                    .FirstAssignableToTypeNameOrDefault("System.Text.Json.Serialization.JsonPolymorphicAttribute", TypeNameStyle.FullName);
+                return new SystemTextJsonInheritanceWrapper(jsonPolymorphicAttribute?.TypeDiscriminatorPropertyName ?? "$type", jsonDerivedTypeAttributes);
+            }
+
             return null;
         }
 
+        private class SystemTextJsonInheritanceWrapper
+        {
+            private readonly dynamic[] _jsonDerivedTypeAttributes;
+
+            public SystemTextJsonInheritanceWrapper(string discriminatorName, dynamic[] jsonDerivedTypeAttributes)
+            {
+                DiscriminatorName = discriminatorName;
+                _jsonDerivedTypeAttributes = jsonDerivedTypeAttributes;
+            }
+
+            public string DiscriminatorName { get; }
+
+            public string GetDiscriminatorValue(Type type)
+            {
+                return _jsonDerivedTypeAttributes.FirstOrDefault(a => a.DerivedType == type)?.TypeDiscriminator
+                    ?? throw new InvalidOperationException($"Discriminator value for {type.FullName} not found.");
+            }
+        }
+
         private string TryGetInheritanceDiscriminatorName(object jsonInheritanceConverter)
         {
             return ObjectExtensions.TryGetPropertyValue(

diff --git a/src/NJsonSchema/OpenApiDiscriminator.cs b/src/NJsonSchema/OpenApiDiscriminator.cs
@@ -10,7 +10,6 @@
 using Newtonsoft.Json;
 using System.Collections.Generic;
 using System.Reflection;
-using NJsonSchema.Infrastructure;
 using NJsonSchema.References;
 using Newtonsoft.Json.Linq;
 
@@ -37,14 +36,12 @@ public class OpenApiDiscriminator
         /// <param name="schema">The schema.</param>
         public void AddMapping(Type type, JsonSchema schema)
         {
-            dynamic converter = JsonInheritanceConverter;
-
             var getDiscriminatorValueMethod = JsonInheritanceConverter?.GetType()
                 .GetRuntimeMethod("GetDiscriminatorValue", new Type[] { typeof(Type) });
 
             if (getDiscriminatorValueMethod != null)
             {
-                var discriminatorValue = converter.GetDiscriminatorValue(type);
+                var discriminatorValue = (string)getDiscriminatorValueMethod.Invoke(JsonInheritanceConverter, new[] { type } );
                 Mapping[discriminatorValue] = new JsonSchema { Reference = schema.ActualSchema };
             }
             else