From 9edf46b697ed1f7ee1f5ef66dfa75a0a138f3f89 Mon Sep 17 00:00:00 2001
From: Eric Liu <ericxliu@gmail.com>
Date: Wed, 14 Oct 2026 20:29:39 -0700
Subject: [PATCH] Validate the selected union member with serdevalid

Signed-off-by: Eric Liu <ericxliu@gmail.com>
---
 src/one_any_of.rs         | 12 ++++++++++-
 tests/union_validation.rs | 42 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 tests/union_validation.rs

diff --git a/src/one_any_of.rs b/src/one_any_of.rs
index f3dcaa606..58b034c92 100644
--- a/src/one_any_of.rs
+++ b/src/one_any_of.rs
@@ -20,7 +20,6 @@ macro_rules! common_one_any_of {
     ) => {
         #[doc = concat!("`", stringify!($t), "` type.\n\nThis allows modelling of ", stringify!($schema), " JSON schemas.")]
         #[cfg_attr(feature = "conversion", derive(LabelledGenericEnum))]
-        #[cfg_attr(feature = "serdevalid", derive(Validate))]
         #[derive(Debug, PartialEq, Clone)]
         pub enum $t<$($i),*> where
             $($i: PartialEq,)*
@@ -31,6 +30,17 @@ macro_rules! common_one_any_of {
             ),*
         }
 
+        #[cfg(feature = "serdevalid")]
+        impl<$($i),*> Validate for $t<$($i),*> where
+            $($i: PartialEq + Validate,)*
+        {
+            fn validate(&self) -> Result<(), serde_valid::validation::Errors> {
+                match self {
+                    $(Self::$i(inner) => inner.validate()),*
+                }
+            }
+        }
+
         impl<$($i),*> Serialize for $t<$($i),*> where
             $($i: PartialEq + Serialize,)*
         {
diff --git a/tests/union_validation.rs b/tests/union_validation.rs
new file mode 100644
index 000000000..f3d26104b
--- /dev/null
+++ b/tests/union_validation.rs
@@ -0,0 +1,42 @@
+#![cfg(feature = "serdevalid")]
+
+use serde_valid::Validate;
+use swagger::{AnyOf2, OneOf2};
+
+#[derive(Debug, PartialEq, Validate)]
+struct Positive {
+    #[validate(minimum = 1)]
+    value: i32,
+}
+
+#[test]
+fn oneof_validates_the_selected_member() {
+    for value in [0, 1] {
+        for union in [
+            OneOf2::<Positive, Positive>::A(Positive { value }),
+            OneOf2::B(Positive { value }),
+        ] {
+            assert_eq!(union.validate().is_ok(), value == 1);
+        }
+    }
+}
+
+#[test]
+fn anyof_validates_the_selected_member() {
+    for value in [0, 1] {
+        for union in [
+            AnyOf2::<Positive, Positive>::A(Positive { value }),
+            AnyOf2::B(Positive { value }),
+        ] {
+            assert_eq!(union.validate().is_ok(), value == 1);
+        }
+    }
+}
+
+#[test]
+fn unions_with_primitive_members_still_serialize_and_deserialize() {
+    let oneof: OneOf2<u32, String> = serde_json::from_str("\"future\"").unwrap();
+    assert_eq!(serde_json::to_string(&oneof).unwrap(), "\"future\"");
+    let anyof: AnyOf2<u32, String> = serde_json::from_str("42").unwrap();
+    assert_eq!(serde_json::to_string(&anyof).unwrap(), "42");
+}