From 09f6e032ec3824c17dacf60d7eee0df232b5fb60 Mon Sep 17 00:00:00 2001
From: vasayxtx <vasayxtx@gmail.com>
Date: Thu, 17 Feb 2022 00:52:07 +0300
Subject: [PATCH] Fix openapi3 validation: path param must be required

---
 openapi3/loader_test.go                 | 1 +
 openapi3/parameter.go                   | 4 ++++
 openapi3filter/req_resp_decoder_test.go | 1 +
 openapi3filter/validation_test.go       | 7 ++++---
 4 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/openapi3/loader_test.go b/openapi3/loader_test.go
index eb293148d..384e54d87 100644
--- a/openapi3/loader_test.go
+++ b/openapi3/loader_test.go
@@ -412,6 +412,7 @@ paths:
       parameters:
         - name: id,
           in: path
+          required: true
           schema:
             type: string
       responses:
diff --git a/openapi3/parameter.go b/openapi3/parameter.go
index 2081e4e1d..a0b8ed11f 100644
--- a/openapi3/parameter.go
+++ b/openapi3/parameter.go
@@ -252,6 +252,10 @@ func (value *Parameter) Validate(ctx context.Context) error {
 		return fmt.Errorf("parameter can't have 'in' value %q", value.In)
 	}
 
+	if in == ParameterInPath && !value.Required {
+		return fmt.Errorf("path parameter %q must be required", value.Name)
+	}
+
 	// Validate a parameter's serialization method.
 	sm, err := value.SerializationMethod()
 	if err != nil {
diff --git a/openapi3filter/req_resp_decoder_test.go b/openapi3filter/req_resp_decoder_test.go
index 34e63712d..f40a7a53e 100644
--- a/openapi3filter/req_resp_decoder_test.go
+++ b/openapi3filter/req_resp_decoder_test.go
@@ -908,6 +908,7 @@ func TestDecodeParameter(t *testing.T) {
 					path := "/test"
 					if tc.path != "" {
 						path += "/{" + tc.param.Name + "}"
+						tc.param.Required = true
 					}
 
 					info := &openapi3.Info{
diff --git a/openapi3filter/validation_test.go b/openapi3filter/validation_test.go
index d4d0a12f1..2f7cf80e6 100644
--- a/openapi3filter/validation_test.go
+++ b/openapi3filter/validation_test.go
@@ -62,9 +62,10 @@ func TestFilter(t *testing.T) {
 					Parameters: openapi3.Parameters{
 						{
 							Value: &openapi3.Parameter{
-								In:     "path",
-								Name:   "pathArg",
-								Schema: openapi3.NewStringSchema().WithMaxLength(2).NewRef(),
+								In:       "path",
+								Name:     "pathArg",
+								Schema:   openapi3.NewStringSchema().WithMaxLength(2).NewRef(),
+								Required: true,
 							},
 						},
 						{