From 178e1801e98bcf4a32d1fff225242fe6b51ba0b8 Mon Sep 17 00:00:00 2001
From: David Pedersen <david.pdrsn@gmail.com>
Date: Sun, 15 May 2022 16:17:45 +0100
Subject: [PATCH] Add `axum_extra::extract::Form` (#1031)

* Add `axum_extra::extra::Form`

* update tokio-util ban
---
 axum-extra/CHANGELOG.md        |   2 +-
 axum-extra/Cargo.toml          |   2 +
 axum-extra/src/extract/form.rs | 136 +++++++++++++++++++++++++++++++++
 axum-extra/src/extract/mod.rs  |   7 ++
 axum/CHANGELOG.md              |   1 +
 axum/src/extract/form.rs       |   4 +-
 axum/src/extract/mod.rs        |  11 +--
 axum/src/extract/query.rs      |   2 +-
 axum/src/extract/rejection.rs  |   5 +-
 deny.toml                      |   4 +-
 10 files changed, 161 insertions(+), 13 deletions(-)
 create mode 100644 axum-extra/src/extract/form.rs

diff --git a/axum-extra/CHANGELOG.md b/axum-extra/CHANGELOG.md
index 0175d6f6..6784d878 100644
--- a/axum-extra/CHANGELOG.md
+++ b/axum-extra/CHANGELOG.md
@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning].
 
 # Unreleased
 
-- None.
+- **added:** Add `extract::Form` which supports multi-value items
 
 # 0.3.1 (10. May, 2022)
 
diff --git a/axum-extra/Cargo.toml b/axum-extra/Cargo.toml
index b5c8c1a6..5a8d03c9 100644
--- a/axum-extra/Cargo.toml
+++ b/axum-extra/Cargo.toml
@@ -17,6 +17,7 @@ typed-routing = ["axum-macros", "serde", "percent-encoding"]
 cookie = ["cookie-lib"]
 cookie-signed = ["cookie", "cookie-lib/signed"]
 cookie-private = ["cookie", "cookie-lib/private"]
+form = ["serde", "serde_html_form"]
 spa = ["tower-http/fs"]
 
 [dependencies]
@@ -36,6 +37,7 @@ serde = { version = "1.0", optional = true }
 serde_json = { version = "1.0.71", optional = true }
 percent-encoding = { version = "2.1", optional = true }
 cookie-lib = { package = "cookie", version = "0.16", features = ["percent-encode"], optional = true }
+serde_html_form = { version = "0.1", optional = true }
 
 [dev-dependencies]
 axum = { path = "../axum", version = "0.5", features = ["headers"] }
diff --git a/axum-extra/src/extract/form.rs b/axum-extra/src/extract/form.rs
new file mode 100644
index 00000000..bcd8c180
--- /dev/null
+++ b/axum-extra/src/extract/form.rs
@@ -0,0 +1,136 @@
+use axum::{
+    async_trait,
+    body::HttpBody,
+    extract::{
+        rejection::{FailedToDeserializeQueryString, FormRejection, InvalidFormContentType},
+        FromRequest, RequestParts,
+    },
+    BoxError,
+};
+use bytes::Bytes;
+use http::{header, Method};
+use serde::de::DeserializeOwned;
+use std::ops::Deref;
+
+/// Extractor that deserializes `application/x-www-form-urlencoded` requests
+/// into some type.
+///
+/// `T` is expected to implement [`serde::Deserialize`].
+///
+/// # Differences from `axum::extract::Form`
+///
+/// This extractor uses [`serde_html_form`] under-the-hood which supports multi-value items. These
+/// are sent by multiple `<input>` attributes of the same name (e.g. checkboxes) and `<select>`s
+/// with the `multiple` attribute. Those values can be collected into a `Vec` or other sequential
+/// container.
+///
+/// # Example
+///
+/// ```rust,no_run
+/// use axum_extra::extract::Form;
+/// use serde::Deserialize;
+///
+/// #[derive(Deserialize)]
+/// struct Payload {
+///     #[serde(rename = "value")]
+///     values: Vec<String>,
+/// }
+///
+/// async fn accept_form(Form(payload): Form<Payload>) {
+///     // ...
+/// }
+/// ```
+///
+/// [`serde_html_form`]: https://crates.io/crates/serde_html_form
+#[derive(Debug, Clone, Copy, Default)]
+pub struct Form<T>(pub T);
+
+impl<T> Deref for Form<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+#[async_trait]
+impl<T, B> FromRequest<B> for Form<T>
+where
+    T: DeserializeOwned,
+    B: HttpBody + Send,
+    B::Data: Send,
+    B::Error: Into<BoxError>,
+{
+    type Rejection = FormRejection;
+
+    async fn from_request(req: &mut RequestParts<B>) -> Result<Self, Self::Rejection> {
+        if req.method() == Method::GET {
+            let query = req.uri().query().unwrap_or_default();
+            let value = serde_html_form::from_str(query)
+                .map_err(FailedToDeserializeQueryString::__private_new::<T, _>)?;
+            Ok(Form(value))
+        } else {
+            if !has_content_type(req, &mime::APPLICATION_WWW_FORM_URLENCODED) {
+                return Err(InvalidFormContentType::default().into());
+            }
+
+            let bytes = Bytes::from_request(req).await?;
+            let value = serde_html_form::from_bytes(&bytes)
+                .map_err(FailedToDeserializeQueryString::__private_new::<T, _>)?;
+
+            Ok(Form(value))
+        }
+    }
+}
+
+// this is duplicated in `axum/src/extract/mod.rs`
+fn has_content_type<B>(req: &RequestParts<B>, expected_content_type: &mime::Mime) -> bool {
+    let content_type = if let Some(content_type) = req.headers().get(header::CONTENT_TYPE) {
+        content_type
+    } else {
+        return false;
+    };
+
+    let content_type = if let Ok(content_type) = content_type.to_str() {
+        content_type
+    } else {
+        return false;
+    };
+
+    content_type.starts_with(expected_content_type.as_ref())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::test_helpers::*;
+    use axum::{routing::post, Router};
+    use http::{header::CONTENT_TYPE, StatusCode};
+    use serde::Deserialize;
+
+    #[tokio::test]
+    async fn supports_multiple_values() {
+        #[derive(Deserialize)]
+        struct Data {
+            #[serde(rename = "value")]
+            values: Vec<String>,
+        }
+
+        let app = Router::new().route(
+            "/",
+            post(|Form(data): Form<Data>| async move { data.values.join(",") }),
+        );
+
+        let client = TestClient::new(app);
+
+        let res = client
+            .post("/")
+            .header(CONTENT_TYPE, "application/x-www-form-urlencoded")
+            .body("value=one&value=two")
+            .send()
+            .await;
+
+        assert_eq!(res.status(), StatusCode::OK);
+        assert_eq!(res.text().await, "one,two");
+    }
+}
diff --git a/axum-extra/src/extract/mod.rs b/axum-extra/src/extract/mod.rs
index ec5fe1ad..4a98c716 100644
--- a/axum-extra/src/extract/mod.rs
+++ b/axum-extra/src/extract/mod.rs
@@ -1,6 +1,10 @@
 //! Additional extractors.
 
 mod cached;
+
+#[cfg(feature = "form")]
+mod form;
+
 #[cfg(feature = "cookie")]
 pub mod cookie;
 
@@ -14,3 +18,6 @@ pub use self::cookie::PrivateCookieJar;
 
 #[cfg(feature = "cookie-signed")]
 pub use self::cookie::SignedCookieJar;
+
+#[cfg(feature = "form")]
+pub use self::form::Form;
diff --git a/axum/CHANGELOG.md b/axum/CHANGELOG.md
index 8e6045f0..40d7b51c 100644
--- a/axum/CHANGELOG.md
+++ b/axum/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `Path<(String, String)>` or `Path<SomeStruct>` ([#1023])
 - **fixed:** `PathRejection::WrongNumberOfParameters` now uses `500 Internal Server Error` since
   its a programmer error and not a client error ([#1023])
+- **fixed:** Fix `InvalidFormContentType` mentioning the wrong content type
 
 [#1022]: https://github.com/tokio-rs/axum/pull/1022
 [#1023]: https://github.com/tokio-rs/axum/pull/1023
diff --git a/axum/src/extract/form.rs b/axum/src/extract/form.rs
index f47c4068..4f0295af 100644
--- a/axum/src/extract/form.rs
+++ b/axum/src/extract/form.rs
@@ -58,7 +58,7 @@ where
         if req.method() == Method::GET {
             let query = req.uri().query().unwrap_or_default();
             let value = serde_urlencoded::from_str(query)
-                .map_err(FailedToDeserializeQueryString::new::<T, _>)?;
+                .map_err(FailedToDeserializeQueryString::__private_new::<T, _>)?;
             Ok(Form(value))
         } else {
             if !has_content_type(req, &mime::APPLICATION_WWW_FORM_URLENCODED) {
@@ -67,7 +67,7 @@ where
 
             let bytes = Bytes::from_request(req).await?;
             let value = serde_urlencoded::from_bytes(&bytes)
-                .map_err(FailedToDeserializeQueryString::new::<T, _>)?;
+                .map_err(FailedToDeserializeQueryString::__private_new::<T, _>)?;
 
             Ok(Form(value))
         }
diff --git a/axum/src/extract/mod.rs b/axum/src/extract/mod.rs
index cde177a7..6e17d973 100644
--- a/axum/src/extract/mod.rs
+++ b/axum/src/extract/mod.rs
@@ -78,7 +78,12 @@ pub use self::ws::WebSocketUpgrade;
 #[doc(no_inline)]
 pub use crate::TypedHeader;
 
-pub(crate) fn has_content_type<B>(
+pub(crate) fn take_body<B>(req: &mut RequestParts<B>) -> Result<B, BodyAlreadyExtracted> {
+    req.take_body().ok_or_else(BodyAlreadyExtracted::default)
+}
+
+// this is duplicated in `axum-extra/src/extract/form.rs`
+pub(super) fn has_content_type<B>(
     req: &RequestParts<B>,
     expected_content_type: &mime::Mime,
 ) -> bool {
@@ -97,10 +102,6 @@ pub(crate) fn has_content_type<B>(
     content_type.starts_with(expected_content_type.as_ref())
 }
 
-pub(crate) fn take_body<B>(req: &mut RequestParts<B>) -> Result<B, BodyAlreadyExtracted> {
-    req.take_body().ok_or_else(BodyAlreadyExtracted::default)
-}
-
 #[cfg(test)]
 mod tests {
     use crate::{routing::get, test_helpers::*, Router};
diff --git a/axum/src/extract/query.rs b/axum/src/extract/query.rs
index bf675f66..c267ce05 100644
--- a/axum/src/extract/query.rs
+++ b/axum/src/extract/query.rs
@@ -59,7 +59,7 @@ where
     async fn from_request(req: &mut RequestParts<B>) -> Result<Self, Self::Rejection> {
         let query = req.uri().query().unwrap_or_default();
         let value = serde_urlencoded::from_str(query)
-            .map_err(FailedToDeserializeQueryString::new::<T, _>)?;
+            .map_err(FailedToDeserializeQueryString::__private_new::<T, _>)?;
         Ok(Query(value))
     }
 }
diff --git a/axum/src/extract/rejection.rs b/axum/src/extract/rejection.rs
index 4d13faee..68e72e6b 100644
--- a/axum/src/extract/rejection.rs
+++ b/axum/src/extract/rejection.rs
@@ -82,7 +82,7 @@ define_rejection! {
 
 define_rejection! {
     #[status = UNSUPPORTED_MEDIA_TYPE]
-    #[body = "Form requests must have `Content-Type: x-www-form-urlencoded`"]
+    #[body = "Form requests must have `Content-Type: application/x-www-form-urlencoded`"]
     /// Rejection type used if you try and extract the request more than once.
     pub struct InvalidFormContentType;
 }
@@ -104,7 +104,8 @@ pub struct FailedToDeserializeQueryString {
 }
 
 impl FailedToDeserializeQueryString {
-    pub(super) fn new<T, E>(error: E) -> Self
+    #[doc(hidden)]
+    pub fn __private_new<T, E>(error: E) -> Self
     where
         E: Into<BoxError>,
     {
diff --git a/deny.toml b/deny.toml
index 6548faa2..33e74a8d 100644
--- a/deny.toml
+++ b/deny.toml
@@ -46,8 +46,8 @@ skip-tree = [
 ]
 skip = [
     { name = "spin", version = "=0.5.2" },
-    # old version pulled in by h2
-    { name = "tokio-util", version = "=0.6.9" },
+    # old version pulled in by reqwest which is only a dev dependency
+    { name = "tokio-util", version = "=0.6.10" },
 ]
 
 [sources]