danielgtaylor · Mcklmo · Sep 14, 2025
diff --git a/adapters/humamux/humagmux_test.go b/adapters/humamux/humagmux_test.go
@@ -133,3 +133,63 @@ func BenchmarkHumaGorillaMux(b *testing.B) {
 		}
 	}
 }
+
+func TestOperationWithoutIDAndInlineRequestTypeDefinitionNotPanics(t *testing.T) {
+	r := mux.NewRouter()
+	api := New(r, huma.DefaultConfig("Test", "1.0.0"))
+
+	var (
+		op1 = huma.Operation{Method: http.MethodGet, Path: "/1"} // no OperationID
+		op2 = huma.Operation{Method: http.MethodGet, Path: "/2"} // no OperationID
+	)
+
+	huma.Register(api, op1, func(ctx context.Context, i *struct { // inline request input type definition
+		Body struct {
+			Test1 string // field name varying
+		}
+	},
+	) (*struct{}, error,
+	) {
+		return nil, nil
+	})
+
+	huma.Register(api, op2, func(ctx context.Context, i *struct { // inline request input type definition
+		Body struct {
+			Test2 string // field name varying
+		}
+	},
+	) (*struct{}, error,
+	) {
+		return nil, nil
+	})
+}
+
+func TestOperationWithoutIDAndInlineResponseTypeDefinitionNotPanics(t *testing.T) {
+	r := mux.NewRouter()
+	api := New(r, huma.DefaultConfig("", ""))
+
+	var (
+		op1 = huma.Operation{Method: http.MethodGet, Path: "/1"} // no OperationID
+		op2 = huma.Operation{Method: http.MethodGet, Path: "/2"} // no OperationID
+	)
+
+	huma.Register(api, op1, func(ctx context.Context, i *struct{},
+	) (*struct { // inline response output type definition
+		Body struct {
+			Test1 string // field name varying
+		}
+	}, error,
+	) {
+		return nil, nil
+	})
+
+	huma.Register(api, op2, func(ctx context.Context, i *struct{},
+	) (*struct { // inline response output type definition
+		Body struct {
+			Test2 string // field name varying
+		}
+	}, error,
+	) {
+		return nil, nil
+	})
+}
diff --git a/huma.go b/huma.go
@@ -31,10 +31,12 @@ import (
 
 var errDeadlineUnsupported = fmt.Errorf("%w", http.ErrNotSupported)
 
-var bodyCallbackType = reflect.TypeOf(func(Context) {})
-var cookieType = reflect.TypeOf((*http.Cookie)(nil)).Elem()
-var fmtStringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
-var stringType = reflect.TypeOf("")
+var (
+	bodyCallbackType = reflect.TypeOf(func(Context) {})
+	cookieType       = reflect.TypeOf((*http.Cookie)(nil)).Elem()
+	fmtStringerType  = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
+	stringType       = reflect.TypeOf("")
+)
 
 // SetReadDeadline is a utility to set the read deadline on a response writer,
 // if possible. If not, it will not incur any allocations (unlike the stdlib
@@ -714,7 +716,7 @@ func Register[I, O any](api API, op Operation, handler func(context.Context, *I)
 				}
 			}
 
-			var receiver = f
+			receiver := f
 			if f.Addr().Type().Implements(reflect.TypeFor[ParamWrapper]()) {
 				receiver = f.Addr().Interface().(ParamWrapper).Receiver()
 			}
@@ -1221,7 +1223,7 @@ func setRequestBodyFromBody(op *Operation, registry Registry, fBody reflect.Stru
 		op.RequestBody.Content[contentType] = &MediaType{}
 	}
 	if op.RequestBody.Content[contentType].Schema == nil {
-		hint := getHint(inputType, fBody.Name, op.OperationID+"Request")
+		hint := getHint(inputType, fBody.Name, getDefaultHint(op.OperationID, registry, inputType, "Request"))
 		if nameHint := fBody.Tag.Get("nameHint"); nameHint != "" {
 			hint = nameHint
 		}
@@ -1230,6 +1232,24 @@ func setRequestBodyFromBody(op *Operation, registry Registry, fBody reflect.Stru
 	}
 }
 
+// getDefaultHint checks if the hint already exists in the registry and returns a new hint if it does.
+//
+// It suffixes the hint with an increasing number if it already exists, starting from 1.
+//
+// However, the operationID takes precedence if it is not empty.
+func getDefaultHint(operationID string, registry Registry, inputType reflect.Type, defaultPrefix string) string {
+	if operationID != "" {
+		return operationID + defaultPrefix
+	}
+
+	defaultHint := defaultPrefix
+	for i := 1; registry.NameExistsInSchema(inputType, defaultHint); i++ {
+		defaultHint = defaultPrefix + strconv.Itoa(i)
+	}
+
+	return defaultHint
+}
+
 type rawBodyType int
 
 const (
@@ -1359,7 +1379,7 @@ func processOutputType(outputType reflect.Type, op *Operation, registry Registry
 			op.Responses[statusStr].Headers = map[string]*Param{}
 		}
 		if !outBodyFunc {
-			hint := getHint(outputType, f.Name, op.OperationID+"Response")
+			hint := getHint(outputType, f.Name, getDefaultHint(op.OperationID, registry, outputType, "Response"))
 			if nameHint := f.Tag.Get("nameHint"); nameHint != "" {
 				hint = nameHint
 			}

diff --git a/registry.go b/registry.go
@@ -15,6 +15,7 @@ import (
 // schemas to exist while being flexible enough to support other use cases
 // like only inline objects (no refs) or always using refs for structs.
 type Registry interface {
+	NameExistsInSchema(t reflect.Type, hint string) bool
 	Schema(t reflect.Type, allowRef bool, hint string) *Schema
 	SchemaFromRef(ref string) *Schema
 	TypeFromRef(ref string) reflect.Type
@@ -160,6 +161,11 @@ func (r *mapRegistry) RegisterTypeAlias(t reflect.Type, alias reflect.Type) {
 	r.aliases[t] = alias
 }
 
+func (r *mapRegistry) NameExistsInSchema(t reflect.Type, hint string) bool {
+	_, ok := r.schemas[r.namer(t, hint)]
+	return ok
+}
+
 // NewMapRegistry creates a new registry that stores schemas in a map and
 // returns references to them using the given prefix.
 func NewMapRegistry(prefix string, namer func(t reflect.Type, hint string) string) Registry {