AllOf with one $ref generates code with a base class.

specs/Qowaiv.CodeGeneration.Specs/Generated/AllOfExamples/SomeBaseClass.generated.cs

@@ -0,0 +1,20 @@
+// ------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+// ------------------------------------------------------------------------------
+
+#nullable enable
+
+namespace AllOfExamples;
+
+[System.Text.Json.Serialization.JsonDerivedType(typeof(AllOfExamples.SomeChildClass))]
+public partial record SomeBaseClass
+{
+    [System.Text.Json.Serialization.JsonPropertyName("id")]
+    [Qowaiv.Validation.DataAnnotations.Optional]
+    public long Id { get; init; }
+}

specs/Qowaiv.CodeGeneration.Specs/Generated/AllOfExamples/SomeChildClass.generated.cs

@@ -0,0 +1,19 @@
+// ------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+// ------------------------------------------------------------------------------
+
+#nullable enable
+
+namespace AllOfExamples;
+
+public sealed partial record SomeChildClass : AllOfExamples.SomeBaseClass
+{
+    [System.Text.Json.Serialization.JsonPropertyName("email")]
+    [Qowaiv.Validation.DataAnnotations.Optional]
+    public Qowaiv.EmailAddress Email { get; init; }
+}

specs/Qowaiv.CodeGeneration.Specs/OpenApi/Definitions/all-of.json

@@ -0,0 +1,38 @@
+{
+  "openapi": "3.0.2",
+  "info": {
+    "title": "All Of example",
+    "version": "1.0.0"
+  },
+  "paths": {},
+  "components": {
+    "schemas": {
+      "SomeBaseClass": {
+        "type": "object",
+        "properties": {
+          "id": {
+            "type": "integer",
+            "format": "int64",
+            "example": 1
+          }
+        }
+      },
+      "SomeChildClass": {
+        "allOf": [
+          {
+            "$ref": "#/components/schemas/SomeBaseClass"
+          },
+          {
+            "type": "object",
+            "properties": {
+              "email": {
+                "type": "string",
+                "format": "email"
+              }
+            }
+          }
+        ]
+      }
+    }
+  }
+}

specs/Qowaiv.CodeGeneration.Specs/OpenApi/Resolve_specs.cs

@@ -9,6 +9,7 @@ namespace Open_API.Resolve_specs;
 public class Generates
 {
     private static readonly FileInfo PetShop_json = new("./OpenApi/Definitions/pet-shop.json");
+    private static readonly FileInfo AllOf_json = new("./OpenApi/Definitions/all-of.json");
 
     [Test]
     public void Compiling_code()
@@ -21,7 +22,24 @@ public void Compiling_code()
         {
             RootDirectory = new("../../../../../specs/Qowaiv.CodeGeneration.Specs/Generated/PetShopBoys"),
             RootNamespace = "PetShopBoys",
-            Headers = new Code[] { new AutoGeneratedHeader(), NullableHeader.Enable },
+            Headers = [new AutoGeneratedHeader(), NullableHeader.Enable],
+        };
+
+        code.Save(codeFileSettings);
+    }
+
+    [Test]
+    public void base_class_for_all_off()
+    {
+        var result = OpenApiCode.Resolve(AllOf_json, new OpenApiTypeResolver("AllOfExamples"));
+
+        var code = result.Should().BeValid().WithoutMessages().Value;
+
+        var codeFileSettings = new CodeFileWriterSettings
+        {
+            RootDirectory = new("../../../../../specs/Qowaiv.CodeGeneration.Specs/Generated/AllOfExamples"),
+            RootNamespace = "AllOfExamples",
+            Headers = [new AutoGeneratedHeader(), NullableHeader.Enable],
         };
 
         code.Save(codeFileSettings);

src/Qowaiv.CodeGeneration.OpenApi/OpenApiTypeResolver.Decorate.cs

@@ -28,7 +28,6 @@ public virtual IEnumerable<AttributeInfo> DecorateModel(Class @class, ResolveOpe
         return AttributeInfo.System_Text_Json_Serialization_JsonDerivedTypeAttribute(derivedType);
     }
 
-
     [Pure]
     protected virtual IEnumerable<AttributeInfo> DecorateProperty(Property property, ResolveOpenApiSchema schema)
     {

src/Qowaiv.CodeGeneration.OpenApi/OpenApiTypeResolver.ResolveType.cs

@@ -43,8 +43,8 @@ _ when schema.Enum.Any() => ResolveEnum(schema),
         OpenApiType.@string => ResolveString(schema),
         OpenApiType.array => ResolveArray(schema),
         OpenApiType.@object => ResolveObject(schema),
-        _ when schema.OneOf.Any() => ResolveOneOf(schema),
         _ when schema.AllOf.Any() => ResolveAllOf(schema),
+        _ when schema.OneOf.Any() => ResolveOneOf(schema),
         _ => ResolveOther(schema),
     };
 
@@ -236,33 +236,46 @@ static bool IsNone(EnumerationField field)
     /// Resolves the <see cref="Type"/> when there is at least one <see cref="ResolveOpenApiSchema.AllOf"/>'s.
     /// </summary>
     [Pure]
-    [Obsolete("Will become private. Use ResolveCustomization(schema) instead.")]
-    protected virtual Type? ResolveAllOf(ResolveOpenApiSchema schema)
+    private Type? ResolveAllOf(ResolveOpenApiSchema schema)
     {
-        if (schema.AllOf.Count() == 1)
+        var bases = schema.AllOf.Where(b => b.Reference is { }).ToArray();
+        var inherit = schema.AllOf.Where(b => b.Reference is null).ToArray();
+
+        if (bases.Length == 1)
         {
-            return ResolveDerivedFrom(schema, schema.AllOf.First());
-        }
-        else throw new NotSupportedException($"Schema with type multiple all-off is not supported.");
-    }
+            if (inherit.Length == 0)
+            {
+                return Resolve(bases[0]);
+            }
+            else if (inherit.Length == 1
+                && Resolve(bases[0]) is { } @base
+                && Resolve(inherit[0].WithBase(@base)) is { } type)
+            {
+                AddDerivedType(@base, type, schema);
 
-    [Pure]
-    private Type? ResolveDerivedFrom(ResolveOpenApiSchema schema, ResolveOpenApiSchema parent)
-    {
-        var type = Resolve(parent);
+                return type;
+            }
+        }
+        throw new NotSupportedException($"Schema '{schema.Path}' with type multiple all-off is not supported.");
 
-        if (type is Class @class
-                && @class.GetDerivedTypes() is List<Type> derivedTypes
-                && @class.GetAttributeInfos() is List<AttributeInfo> infos)
+        void AddDerivedType(Type @base, Type type, ResolveOpenApiSchema schema)
         {
-            derivedTypes.AddRange(schema.OneOf.Select(Resolve).OfType<Type>());
-            infos.AddRange(derivedTypes.Select(d => DecorateDerivedType(d, schema)).OfType<AttributeInfo>());
+            if (@base is Class @class
+                && @class.GetDerivedTypes() is List<Type> derivedTypes
+                && @class.GetAttributeInfos() is List<AttributeInfo> infos
+                && !derivedTypes.Exists(t => t.FullName == type.FullName))
+            {
+                derivedTypes.Add(type);
+                if (DecorateDerivedType(type, schema) is { } attr)
+                {
+                    infos.Add(attr);
+                }
+            }
         }
-        return type;
     }
 
     /// <summary>Resolves the <see cref="Type"/> for <see cref="OpenApiType.None"/>.</summary>
     [Pure]
     protected virtual Type? ResolveOther(ResolveOpenApiSchema schema)
-        => throw new NotSupportedException($"Schema with type '{schema.Type}' is not supported.");
+        => throw new NotSupportedException($"Schema '{schema.Path}' with type '{schema.Type}' is not supported.");
 }

src/Qowaiv.CodeGeneration.OpenApi/ResolveOpenApiSchema.cs

@@ -18,37 +18,13 @@ public readonly partial struct ResolveOpenApiSchema(
     public string? ReferenceId => Reference?.Id;
 
     /// <inheritdoc cref="OpenApiSchema.AllOf"/>
-    public IEnumerable<ResolveOpenApiSchema> AllOf
-    {
-        get
-        {
-            var self = this;
-            return Schema?.AllOf?.Select(self.With)
-            ?? [];
-        }
-    }
+    public IEnumerable<ResolveOpenApiSchema> AllOf => Schema?.AllOf?.Select(SelectionOf) ?? [];
 
     /// <inheritdoc cref="OpenApiSchema.AnyOf"/>
-    public IEnumerable<ResolveOpenApiSchema> AnyOf
-    {
-        get
-        {
-            var self = this;
-            return Schema?.AnyOf?.Select(self.With)
-            ?? [];
-        }
-    }
+    public IEnumerable<ResolveOpenApiSchema> AnyOf => Schema?.AnyOf?.Select(SelectionOf) ?? [];
 
     /// <inheritdoc cref="OpenApiSchema.OneOf"/>
-    public IEnumerable<ResolveOpenApiSchema> OneOf
-    {
-        get
-        {
-            var self = this;
-            return Schema?.OneOf?.Select(self.With)
-            ?? [];
-        }
-    }
+    public IEnumerable<ResolveOpenApiSchema> OneOf => Schema?.OneOf?.Select(SelectionOf) ?? [];
 
     /// <inheritdoc cref="OpenApiSchema.Description"/>
     public string? Description => Schema?.Description;
@@ -142,4 +118,11 @@ public override string ToString()
             return sb.ToString();
         }
     }
+
+    [Pure]
+    private ResolveOpenApiSchema SelectionOf(OpenApiSchema s)
+    => s.Reference is { } r
+        ? new ResolveOpenApiSchema(new(r.ReferenceV3 ?? r.ReferenceV2), s, null)
+        : With(s);
+
 }

src/Qowaiv.CodeGeneration/Types/TypeBase.cs

@@ -211,7 +211,10 @@ public override PropertyInfo[] GetProperties(BindingFlags bindingAttr)
 
     /// <inheritdoc />
     [Pure]
-    protected override TypeAttributes GetAttributeFlagsImpl() => TypeAttributes;
+    protected override TypeAttributes GetAttributeFlagsImpl()
+        => DerivedTypes.Any()
+            ? TypeAttributes ^ TypeAttributes.Sealed
+            : TypeAttributes;
 
     /// <inheritdoc />
     [Pure]