fix: respect Binder interface for primitive types in BindStringToObject

bindstring.go

@@ -33,6 +33,11 @@ import (
 func BindStringToObject(src string, dst interface{}) error {
 	var err error
 
+	// Check if the destination implements Binder interface before any reflection
+	if binder, ok := dst.(Binder); ok {
+		return binder.Bind(src)
+	}
+
 	v := reflect.ValueOf(dst)
 	t := reflect.TypeOf(dst)
 
@@ -107,11 +112,6 @@ func BindStringToObject(src string, dst interface{}) error {
 		}
 		fallthrough
 	case reflect.Struct:
-		// if this is not of type Time or of type Date look to see if this is of type Binder.
-		if dstType, ok := dst.(Binder); ok {
-			return dstType.Bind(src)
-		}
-
 		if t.ConvertibleTo(reflect.TypeOf(time.Time{})) {
 			// Don't fail on empty string.
 			if src == "" {

bindstring_test.go

@@ -24,6 +24,16 @@ import (
 	"github.com/oapi-codegen/runtime/types"
 )
 
+// CustomStringBinder is a string type that implements Binder but not TextUnmarshaler
+// This tests that Binder interface is checked for primitive types
+type CustomStringBinder string
+
+func (c *CustomStringBinder) Bind(src string) error {
+	// Custom binding logic: add a prefix to demonstrate the Bind method was called
+	*c = CustomStringBinder("CUSTOM:" + src)
+	return nil
+}
+
 func TestBindStringToObject(t *testing.T) {
 	var i int
 	assert.NoError(t, BindStringToObject("5", &i))
@@ -209,4 +219,10 @@ func TestBindStringToObject(t *testing.T) {
 	assert.NoError(t, BindStringToObject(uuidString, &dstUUID))
 	assert.Equal(t, dstUUID.String(), uuidString)
 
+	// Checks that primitive types implementing Binder are respected
+	// This tests the fix for ensuring Binder is checked before type reflection
+	var customString CustomStringBinder
+	assert.NoError(t, BindStringToObject("hello", &customString))
+	assert.Equal(t, CustomStringBinder("CUSTOM:hello"), customString)
+
 }