openapi3filter: fix bug where absent optional properties fail validation in form-urlencoded requests

openapi3filter/issue1110_test.go

@@ -0,0 +1,101 @@
+package openapi3filter
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/getkin/kin-openapi/openapi3"
+	"github.com/getkin/kin-openapi/routers/gorillamux"
+)
+
+func TestIssue1110(t *testing.T) {
+	// Test case: POST with application/x-www-form-urlencoded
+	// Schema has two optional properties (not required)
+	// Sending only one param should be valid since no fields are required
+	spec := `
+openapi: 3.0.3
+info:
+  version: 1.0.0
+  title: Test API
+paths:
+  /test:
+    post:
+      summary: Test endpoint with optional form parameters
+      requestBody:
+        content:
+          application/x-www-form-urlencoded:
+            schema:
+              type: object
+              properties:
+                param1:
+                  type: string
+                param2:
+                  type: string
+      responses:
+        '200':
+          description: OK
+`[1:]
+
+	loader := openapi3.NewLoader()
+	ctx := loader.Context
+
+	doc, err := loader.LoadFromData([]byte(spec))
+	require.NoError(t, err)
+
+	err = doc.Validate(ctx)
+	require.NoError(t, err)
+
+	router, err := gorillamux.NewRouter(doc)
+	require.NoError(t, err)
+
+	for _, testcase := range []struct {
+		name       string
+		data       string
+		shouldFail bool
+	}{
+		{
+			name:       "empty body should be valid (no required fields)",
+			data:       "",
+			shouldFail: false,
+		},
+		{
+			name:       "only param1 present, param2 absent - should be valid",
+			data:       "param1=value1",
+			shouldFail: false,
+		},
+		{
+			name:       "only param2 present, param1 absent - should be valid",
+			data:       "param2=value2",
+			shouldFail: false,
+		},
+		{
+			name:       "both params present - should be valid",
+			data:       "param1=value1&param2=value2",
+			shouldFail: false,
+		},
+	} {
+		t.Run(testcase.name, func(t *testing.T) {
+			req, err := http.NewRequest("POST", "/test", strings.NewReader(testcase.data))
+			require.NoError(t, err)
+			req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+
+			route, pathParams, err := router.FindRoute(req)
+			require.NoError(t, err)
+
+			validationInput := &RequestValidationInput{
+				Request:    req,
+				PathParams: pathParams,
+				Route:      route,
+			}
+			err = ValidateRequest(ctx, validationInput)
+			if testcase.shouldFail {
+				require.Error(t, err, "This test should fail: "+testcase.name)
+			} else {
+				require.NoError(t, err, "This test should pass: "+testcase.name)
+			}
+		})
+	}
+}

openapi3filter/req_resp_decoder.go

@@ -1364,8 +1364,8 @@ func decodeSchemaConstructs(dec *urlValuesDecoder, schemas []*openapi3.SchemaRef
 		}
 
 		for name, prop := range schemaRef.Value.Properties {
-			value, _, err := decodeProperty(dec, name, prop, encFn)
-			if err != nil {
+			value, present, err := decodeProperty(dec, name, prop, encFn)
+			if err != nil || !present {
 				continue
 			}
 			if existingValue, exists := obj[name]; exists && !isEqual(existingValue, value) {