feat(embedding): allof embedding structs impl

Author: zdunecki

internal/test/all_of/openapi.yaml

@@ -51,3 +51,15 @@ components:
               type: integer
               format: int64
           required: [ ID ]
+    PersonWithRole:
+      type: object
+      description: |
+        This tests a schema that has both its own properties and an allOf reference.
+        The generated code should embed the allOf ref and inline the own properties.
+      properties:
+        Role:
+          type: string
+      allOf:
+        - $ref: "#/components/schemas/Person"
+      required:
+        - Role

internal/test/all_of/v1/openapi.gen.go

@@ -13,9 +13,20 @@ import (
 func MergeSchemas(schema *openapi3.Schema, path []string) (Schema, error) {
 	allOf := schema.AllOf
 
+	// If the parent schema has its own properties alongside allOf,
+	// include them as a synthetic schema in the allOf list so they
+	// are not lost during merging.
+	if len(schema.Properties) > 0 {
+		parentOnly := *schema
+		parentOnly.AllOf = nil
+		allOf = append(allOf, openapi3.NewSchemaRef("", &parentOnly))
+	}
+
 	// If someone asked for the old way, for backward compatibility, return the
 	// old style result.
-	if globalState.options.Compatibility.OldMergeSchemas || schema.Extensions[extGoEmbedding] == true {
+	// Also use v1 merging when the parent has its own properties, because v1
+	// generates struct embedding for $ref types which preserves the type hierarchy.
+	if globalState.options.Compatibility.OldMergeSchemas || schema.Extensions[extGoEmbedding] == true || len(schema.Properties) > 0 {
 		return mergeSchemasV1(allOf, path)
 	}
 	return mergeSchemas(allOf, path)

internal/test/all_of/v2/openapi.gen.go

@@ -351,19 +351,6 @@ func GenerateGoSchema(sref *openapi3.SchemaRef, path []string) (Schema, error) {
 		return mergedSchema, nil
 	}
 
-	// AllOf is interesting, and useful. It's the union of a number of other
-	// schemas. A common usage is to create a union of an object with an ID,
-	// so that in a RESTful paradigm, the Create operation can return
-	// (object, id), so that other operations can refer to (id)
-	if schema.AllOf != nil {
-		mergedSchema, err := MergeSchemas(schema, path)
-		if err != nil {
-			return Schema{}, fmt.Errorf("error merging schemas: %w", err)
-		}
-		mergedSchema.OAPISchema = schema
-		return mergedSchema, nil
-	}
-
 	// Schema type and format, eg. string / binary
 	t := schema.Type
 	// Handle objects and empty schemas first as a special case