From 1507eb863e5fce9379cdfcb9bb048697749ed4cd Mon Sep 17 00:00:00 2001
From: Henning Surmeier <h.surmeier@mittwald.de>
Date: Thu, 25 Sep 2025 11:29:15 +0200
Subject: [PATCH] add formats to openapi3 numeric types

This was already implemented for openapi31 in https://github.com/swaggest/openapi-go/pull/140
---
 openapi3/example_test.go |  3 ++-
 openapi3/reflect.go      | 16 ++++++++++++++++
 openapi3/reflect_test.go |  2 +-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/openapi3/example_test.go b/openapi3/example_test.go
index eac3617..e4ca7f9 100644
--- a/openapi3/example_test.go
+++ b/openapi3/example_test.go
@@ -244,7 +244,7 @@ paths:
               schema:
                 type: string
           content:
-            application/json:    
+            application/json:
               schema:
                 $ref: "#/components/schemas/Pets"
         default:
@@ -585,6 +585,7 @@ func ExampleReflector_AddOperation_queryObject() {
 	//               type: string
 	//           type: object
 	//         quux:
+	//           format: double
 	//           type: number
 	//       type: object
 	//     Openapi3TestJsonFilter:
diff --git a/openapi3/reflect.go b/openapi3/reflect.go
index c422c74..03603a7 100644
--- a/openapi3/reflect.go
+++ b/openapi3/reflect.go
@@ -26,6 +26,22 @@ func NewReflector() *Reflector {
 	r := &Reflector{}
 	r.SpecEns()
 
+	r.DefaultOptions = append(r.DefaultOptions, jsonschema.InterceptSchema(func(params jsonschema.InterceptSchemaParams) (stop bool, err error) {
+		// See https://spec.openapis.org/oas/v3.0.0.html#data-types.
+		switch params.Value.Kind() { //nolint // Not all kinds have formats defined.
+		case reflect.Int64:
+			params.Schema.WithFormat("int64")
+		case reflect.Int32:
+			params.Schema.WithFormat("int32")
+		case reflect.Float32:
+			params.Schema.WithFormat("float")
+		case reflect.Float64:
+			params.Schema.WithFormat("double")
+		}
+
+		return false, nil
+	}))
+
 	return r
 }
 
diff --git a/openapi3/reflect_test.go b/openapi3/reflect_test.go
index bfc7dd2..55daaad 100644
--- a/openapi3/reflect_test.go
+++ b/openapi3/reflect_test.go
@@ -1086,7 +1086,7 @@ func TestReflector_AddOperation_defName(t *testing.T) {
 	  "paths":{
 		"/foo":{
 		  "post":{
-			"parameters":[{"name":"bar","in":"header","schema":{"type":"number"}}],
+			"parameters":[{"name":"bar","in":"header","schema":{"type":"number","format":"double"}}],
 			"requestBody":{
 			  "content":{
 				"application/json":{"schema":{"$ref":"#/components/schemas/Openapi3TestReqJSON"}},