Add 'required bool' parameter to BindStyledParameterWithLocation

bindform.go

@@ -20,6 +20,7 @@ type RequestBodyEncoding struct {
 	ContentType string
 	Style       string
 	Explode     *bool
+	Required    *bool
 }
 
 func BindMultipart(ptr interface{}, reader multipart.Reader) error {
@@ -64,7 +65,11 @@ func BindForm(ptr interface{}, form map[string][]string, files map[string][]*mul
 				if encoding.Explode != nil {
 					explode = *encoding.Explode
 				}
-				if err := BindStyledParameterWithLocation(encoding.Style, explode, tag, ParamLocationUndefined, value, field.Addr().Interface()); err != nil {
+				var required bool
+				if encoding.Required != nil {
+					required = *encoding.Required
+				}
+				if err := BindStyledParameterWithLocation(encoding.Style, explode, required, tag, ParamLocationUndefined, value, field.Addr().Interface()); err != nil {
 					return err
 				}
 			}

bindparam.go

@@ -31,19 +31,21 @@ import (
 // https://swagger.io/docs/specification/serialization/
 // It is a backward compatible function to clients generated with codegen
 // up to version v1.5.5. v1.5.6+ calls the function below.
-func BindStyledParameter(style string, explode bool, paramName string,
+func BindStyledParameter(style string, explode bool, required bool, paramName string,
 	value string, dest interface{}) error {
-	return BindStyledParameterWithLocation(style, explode, paramName, ParamLocationUndefined, value, dest)
+	return BindStyledParameterWithLocation(style, explode, required, paramName, ParamLocationUndefined, value, dest)
 }
 
 // BindStyledParameterWithLocation binds a parameter as described in the Path Parameters
 // section here to a Go object:
 // https://swagger.io/docs/specification/serialization/
-func BindStyledParameterWithLocation(style string, explode bool, paramName string,
+func BindStyledParameterWithLocation(style string, explode bool, required bool, paramName string,
 	paramLocation ParamLocation, value string, dest interface{}) error {
 
-	if value == "" {
-		return fmt.Errorf("parameter '%s' is empty, can't bind its value", paramName)
+	if required {
+		if value == "" {
+			return fmt.Errorf("parameter '%s' is empty, can't bind its value", paramName)
+		}
 	}
 
 	// Based on the location of the parameter, we need to unescape it properly.

bindparam_test.go

@@ -493,7 +493,7 @@ func TestBindStyledParameterWithLocation(t *testing.T) {
 	expectedBig := big.NewInt(12345678910)
 
 	var dstBigNumber big.Int
-	err := BindStyledParameterWithLocation("simple", false, "id", ParamLocationUndefined,
+	err := BindStyledParameterWithLocation("simple", false, false, "id", ParamLocationUndefined,
 		"12345678910", &dstBigNumber)
 	assert.NoError(t, err)
 	assert.Equal(t, *expectedBig, dstBigNumber)