PathDeserializer: use `deserialize_str` for `deserialize_any` (#2881)

* PathDeserializer: use `deserialize_str` for `deserialize_any`

* fix `deserialize_any` for `seq` and `map`

* add tests for `deserialize_any`

* parse numeric values as well

---------

Co-authored-by: Rob Ede <robjtede@icloud.com>
Co-authored-by: Yuki Okushi <huyuumi.dev@gmail.com>

actix-router/CHANGES.md

@@ -3,6 +3,9 @@
 ## Unreleased
 
 - Minimum supported Rust version (MSRV) is now 1.88.
+- Support `deserialize_any` in `PathDeserializer` (enables derived `#[serde(untagged)]` enums in path segments). [#2881]
+
+[#2881]: https://github.com/actix/actix-web/pull/2881
 
 ## 0.5.3
 

actix-router/src/de.rs

@@ -27,6 +27,9 @@ macro_rules! unsupported_type {
 
 macro_rules! parse_single_value {
     ($trait_fn:ident) => {
+        parse_single_value!($trait_fn, $trait_fn);
+    };
+    ($trait_fn:ident, $visit_fn:ident) => {
         fn $trait_fn<V>(self, visitor: V) -> Result<V::Value, Self::Error>
         where
             V: Visitor<'de>,
@@ -43,7 +46,7 @@ macro_rules! parse_single_value {
                 Value {
                     value: &self.path[0],
                 }
-                .$trait_fn(visitor)
+                .$visit_fn(visitor)
             }
         }
     };
@@ -205,11 +208,11 @@ impl<'de, T: ResourcePath + 'de> Deserializer<'de> for PathDeserializer<'de, T>
         })
     }
 
-    unsupported_type!(deserialize_any, "'any'");
     unsupported_type!(deserialize_option, "Option<T>");
     unsupported_type!(deserialize_identifier, "identifier");
     unsupported_type!(deserialize_ignored_any, "ignored_any");
 
+    parse_single_value!(deserialize_any);
     parse_single_value!(deserialize_bool);
     parse_single_value!(deserialize_i8);
     parse_single_value!(deserialize_i16);
@@ -427,7 +430,39 @@ impl<'de> Deserializer<'de> for Value<'de> {
         Err(de::value::Error::custom("unsupported type: tuple struct"))
     }
 
-    unsupported_type!(deserialize_any, "any");
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value, Self::Error>
+    where
+        V: Visitor<'de>,
+    {
+        let decoded = FULL_QUOTER
+            .with(|q| q.requote_str_lossy(self.value))
+            .map(Cow::Owned)
+            .unwrap_or(Cow::Borrowed(self.value));
+
+        let s = decoded.as_ref();
+        // We have to do it manually here on behalf of serde.
+        if let Ok(v) = s.parse::<u64>() {
+            if let Ok(v) = u32::try_from(v) {
+                return visitor.visit_u32(v);
+            }
+
+            return visitor.visit_u64(v);
+        }
+
+        if let Ok(v) = s.parse::<i64>() {
+            if let Ok(v) = i32::try_from(v) {
+                return visitor.visit_i32(v);
+            }
+
+            return visitor.visit_i64(v);
+        }
+
+        match decoded {
+            Cow::Borrowed(value) => visitor.visit_borrowed_str(value),
+            Cow::Owned(value) => visitor.visit_string(value),
+        }
+    }
+
     unsupported_type!(deserialize_seq, "seq");
     unsupported_type!(deserialize_map, "map");
     unsupported_type!(deserialize_identifier, "identifier");
@@ -704,6 +739,119 @@ mod tests {
         assert_eq!(vals.value, "/");
     }
 
+    #[test]
+    fn deserialize_path_decode_any() {
+        #[derive(Debug, PartialEq)]
+        pub enum AnyEnumCustom {
+            String(String),
+            Int(u32),
+            Other,
+        }
+
+        impl<'de> Deserialize<'de> for AnyEnumCustom {
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+            where
+                D: serde::Deserializer<'de>,
+            {
+                struct Vis;
+                impl<'de> Visitor<'de> for Vis {
+                    type Value = AnyEnumCustom;
+
+                    fn expecting<'a>(&self, f: &mut std::fmt::Formatter<'a>) -> std::fmt::Result {
+                        write!(f, "my thing")
+                    }
+
+                    fn visit_u32<E>(self, v: u32) -> Result<Self::Value, E>
+                    where
+                        E: serde::de::Error,
+                    {
+                        Ok(AnyEnumCustom::Int(v))
+                    }
+
+                    fn visit_u64<E>(self, v: u64) -> Result<Self::Value, E>
+                    where
+                        E: serde::de::Error,
+                    {
+                        match u32::try_from(v) {
+                            Ok(v) => Ok(AnyEnumCustom::Int(v)),
+                            Err(_) => Ok(AnyEnumCustom::String(format!("some str: {v}"))),
+                        }
+                    }
+
+                    fn visit_i64<E>(self, v: i64) -> Result<Self::Value, E>
+                    where
+                        E: serde::de::Error,
+                    {
+                        match u32::try_from(v) {
+                            Ok(v) => Ok(AnyEnumCustom::Int(v)),
+                            Err(_) => Ok(AnyEnumCustom::String(format!("some str: {v}"))),
+                        }
+                    }
+
+                    fn visit_str<E: serde::de::Error>(self, v: &str) -> Result<Self::Value, E> {
+                        v.parse().map(AnyEnumCustom::Int).or_else(|_| {
+                            Ok(match v {
+                                "other" => AnyEnumCustom::Other,
+                                _ => AnyEnumCustom::String(format!("some str: {v}")),
+                            })
+                        })
+                    }
+                }
+
+                deserializer.deserialize_any(Vis)
+            }
+        }
+
+        #[derive(Debug, Deserialize, PartialEq)]
+        #[serde(untagged)]
+        pub enum AnyEnumDerive {
+            String(String),
+            Int(u32),
+            Other,
+        }
+
+        // single
+        let rdef = ResourceDef::new("/{key}");
+
+        let mut path = Path::new("/%25");
+        rdef.capture_match_info(&mut path);
+        let de = PathDeserializer::new(&path);
+        let segment: AnyEnumCustom = serde::Deserialize::deserialize(de).unwrap();
+        assert_eq!(segment, AnyEnumCustom::String("some str: %".to_string()));
+
+        let mut path = Path::new("/%25");
+        rdef.capture_match_info(&mut path);
+        let de = PathDeserializer::new(&path);
+        let segment: AnyEnumDerive = serde::Deserialize::deserialize(de).unwrap();
+        assert_eq!(segment, AnyEnumDerive::String("%".to_string()));
+
+        // seq
+        let rdef = ResourceDef::new("/{key}/{value}");
+
+        let mut path = Path::new("/other/123");
+        rdef.capture_match_info(&mut path);
+        let de = PathDeserializer::new(&path);
+        let segment: (AnyEnumCustom, AnyEnumDerive) = serde::Deserialize::deserialize(de).unwrap();
+        assert_eq!(segment.0, AnyEnumCustom::Other);
+        assert_eq!(segment.1, AnyEnumDerive::Int(123));
+
+        // map
+        #[derive(Deserialize)]
+        struct Vals {
+            key: AnyEnumCustom,
+            value: AnyEnumDerive,
+        }
+
+        let rdef = ResourceDef::new("/{key}/{value}");
+
+        let mut path = Path::new("/123/%2F");
+        rdef.capture_match_info(&mut path);
+        let de = PathDeserializer::new(&path);
+        let vals: Vals = serde::Deserialize::deserialize(de).unwrap();
+        assert_eq!(vals.key, AnyEnumCustom::Int(123));
+        assert_eq!(vals.value, AnyEnumDerive::String("/".to_string()));
+    }
+
     #[test]
     fn deserialize_borrowed() {
         #[derive(Debug, Deserialize)]