fix: apply default tags via TextUnmarshaler

huma_internal_test.go

@@ -1,7 +1,10 @@
 package huma
 
 import (
+	"encoding"
+	"reflect"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -14,3 +17,75 @@ func TestCollectionPath(t *testing.T) {
 	assert.Panics(t, func() { collectionPath([]int{2}) })
 	assert.Panics(t, func() { collectionPath(nil) })
 }
+
+type issue680Duration struct {
+	time.Duration
+}
+
+func (d *issue680Duration) UnmarshalText(data []byte) error {
+	v, err := time.ParseDuration(string(data))
+	if err != nil {
+		return err
+	}
+	d.Duration = v
+	return nil
+}
+
+var _ encoding.TextUnmarshaler = (*issue680Duration)(nil)
+
+func TestConvertTypeTextUnmarshalerDefault(t *testing.T) {
+	got := convertType("Duration", reflect.TypeOf(issue680Duration{}), "10s")
+	d, ok := got.(issue680Duration)
+	if !ok {
+		t.Fatalf("got %T %#v", got, got)
+	}
+	if d.Duration != 10*time.Second {
+		t.Fatalf("duration=%v", d.Duration)
+	}
+}
+
+func TestFindDefaultsTextUnmarshaler(t *testing.T) {
+	type Input struct {
+		Duration issue680Duration `json:"duration" default:"10s"`
+	}
+	r := NewMapRegistry("#/components/schemas/", DefaultSchemaNamer)
+	defaults := findDefaults(r, reflect.TypeOf(Input{}))
+	var in Input
+	v := reflect.ValueOf(&in).Elem()
+	setDefaults(v, defaults)
+	if in.Duration.Duration != 10*time.Second {
+		t.Fatalf("default not applied: %v", in.Duration)
+	}
+}
+
+func TestSchemaFromFieldTextUnmarshalerDefault(t *testing.T) {
+	type Input struct {
+		Duration issue680Duration `json:"duration" default:"10s"`
+	}
+	r := NewMapRegistry("#/components/schemas/", DefaultSchemaNamer)
+	s := SchemaFromType(r, reflect.TypeOf(Input{}))
+	def := s.Properties["duration"].Default
+	if def != "10s" {
+		t.Fatalf("schema default=%#v want %q", def, "10s")
+	}
+}
+
+func TestConvertTypeTextUnmarshalerPointerDefault(t *testing.T) {
+	got := convertType("Duration", reflect.TypeOf((*issue680Duration)(nil)), "10s")
+	d, ok := got.(*issue680Duration)
+	if !ok || d == nil {
+		t.Fatalf("got %T %#v", got, got)
+	}
+	if d.Duration != 10*time.Second {
+		t.Fatalf("duration=%v", d.Duration)
+	}
+}
+
+func TestConvertTypeTextUnmarshalerDefaultInvalid(t *testing.T) {
+	defer func() {
+		if recover() == nil {
+			t.Fatal("expected panic on invalid duration default")
+		}
+	}()
+	_ = convertType("Duration", reflect.TypeOf(issue680Duration{}), "not-a-duration")
+}

schema.go

@@ -504,6 +504,19 @@ func convertType(fieldName string, t reflect.Type, v any) any {
 		return tmp.Interface()
 	}
 
+	target := deref(t)
+	targetPtr := reflect.PointerTo(target)
+	if s, ok := v.(string); ok && (target.Implements(textUnmarshalerType) || targetPtr.Implements(textUnmarshalerType)) {
+		converted := reflect.New(target)
+		if err := converted.Interface().(encoding.TextUnmarshaler).UnmarshalText([]byte(s)); err != nil {
+			panic(fmt.Errorf("unable to convert %v to %v for field '%s': %v: %w", tv, t, fieldName, err, ErrSchemaInvalid))
+		}
+		if t.Kind() == reflect.Pointer {
+			return converted.Interface()
+		}
+		return converted.Elem().Interface()
+	}
+
 	if !tv.ConvertibleTo(deref(t)) {
 		panic(fmt.Errorf("unable to convert %v to %v for field '%s': %w", tv, t, fieldName, ErrSchemaInvalid))
 	}
@@ -557,7 +570,14 @@ func jsonTagValue(r Registry, fieldName string, s *Schema, value string) any {
 func jsonTag(r Registry, f reflect.StructField, s *Schema, name string) any {
 	t := f.Type
 	if value := f.Tag.Get(name); value != "" {
-		return convertType(f.Name, t, jsonTagValue(r, f.Name, s, value))
+		parsed := jsonTagValue(r, f.Name, s, value)
+		base := deref(t)
+		// Keep schema defaults in wire form for TextUnmarshaler string types so
+		// OpenAPI stays a string (e.g. "10s") while findDefaults still converts.
+		if base.Implements(textUnmarshalerType) || reflect.PointerTo(base).Implements(textUnmarshalerType) {
+			return parsed
+		}
+		return convertType(f.Name, t, parsed)
 	}
 	return nil
 }

schema_test.go

@@ -571,6 +571,23 @@ func TestSchema(t *testing.T) {
 				"required": ["value"]
 			}`,
 		},
+		{
+			name: "field-default-text-unmarshaler",
+			input: struct {
+				Value MyDate `json:"value" default:"2020-01-02"`
+			}{},
+			expected: `{
+				"type": "object",
+				"properties": {
+					"value": {
+						"type": "string",
+						"default": "2020-01-02"
+					}
+				},
+				"additionalProperties": false,
+				"required": ["value"]
+			}`,
+		},
 		{
 			name: "field-optional-without-name",
 			input: struct {