extensions middleware and request extensions (#56)

* extensions middleware and request extensions

* fix publish

* request initialisers

* simplify example

* docs

* changelog

* Apply suggestions from code review

Co-authored-by: Alex Butler <alexheretic@gmail.com>

Co-authored-by: Alex Butler <alexheretic@gmail.com>

CHANGELOG.md

@@ -8,6 +8,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - Implementation of `Debug` trait for `RequestBuilder`.
+- A new `RequestInitialiser` trait that can be added to `ClientWithMiddleware`
+- A new `Extension` initialiser that adds extensions to the request
+- Adds `with_extension` method functionality to `RequestBuilder` that can add extensions for the `send` method to use - deprecating `send_with_extensions`.
+
+## [0.1.6] - 2022-04-21
+
+Absolutely nothing changed
 
 ## [0.1.5] - 2022-02-21
 

reqwest-middleware/src/client.rs

@@ -10,6 +10,7 @@ use task_local_extensions::Extensions;
 
 use crate::error::Result;
 use crate::middleware::{Middleware, Next};
+use crate::RequestInitialiser;
 
 /// A `ClientBuilder` is used to build a [`ClientWithMiddleware`].
 ///
@@ -17,6 +18,7 @@ use crate::middleware::{Middleware, Next};
 pub struct ClientBuilder {
     client: Client,
     middleware_stack: Vec<Arc<dyn Middleware>>,
+    initialiser_stack: Vec<Arc<dyn RequestInitialiser>>,
 }
 
 impl ClientBuilder {
@@ -24,6 +26,7 @@ impl ClientBuilder {
         ClientBuilder {
             client,
             middleware_stack: Vec::new(),
+            initialiser_stack: Vec::new(),
         }
     }
 
@@ -47,9 +50,33 @@ impl ClientBuilder {
         self
     }
 
+    /// Convenience method to attach a request initialiser.
+    ///
+    /// If you need to keep a reference to the initialiser after attaching, use [`with_arc_init`].
+    ///
+    /// [`with_arc_init`]: Self::with_arc_init
+    pub fn with_init<I>(self, initialiser: I) -> Self
+    where
+        I: RequestInitialiser,
+    {
+        self.with_arc_init(Arc::new(initialiser))
+    }
+
+    /// Add a request initialiser to the chain. [`with_init`] is more ergonomic if you don't need the `Arc`.
+    ///
+    /// [`with_init`]: Self::with_init
+    pub fn with_arc_init(mut self, initialiser: Arc<dyn RequestInitialiser>) -> Self {
+        self.initialiser_stack.push(initialiser);
+        self
+    }
+
     /// Returns a `ClientWithMiddleware` using this builder configuration.
     pub fn build(self) -> ClientWithMiddleware {
-        ClientWithMiddleware::new(self.client, self.middleware_stack)
+        ClientWithMiddleware {
+            inner: self.client,
+            middleware_stack: self.middleware_stack.into_boxed_slice(),
+            initialiser_stack: self.initialiser_stack.into_boxed_slice(),
+        }
     }
 }
 
@@ -59,6 +86,7 @@ impl ClientBuilder {
 pub struct ClientWithMiddleware {
     inner: reqwest::Client,
     middleware_stack: Box<[Arc<dyn Middleware>]>,
+    initialiser_stack: Box<[Arc<dyn RequestInitialiser>]>,
 }
 
 impl ClientWithMiddleware {
@@ -70,6 +98,8 @@ impl ClientWithMiddleware {
         ClientWithMiddleware {
             inner: client,
             middleware_stack: middleware_stack.into(),
+            // TODO(conradludgate) - allow downstream code to control this manually if desired
+            initialiser_stack: Box::new([]),
         }
     }
 
@@ -105,10 +135,14 @@ impl ClientWithMiddleware {
 
     /// See [`Client::request`]
     pub fn request<U: IntoUrl>(&self, method: Method, url: U) -> RequestBuilder {
-        RequestBuilder {
+        let req = RequestBuilder {
             inner: self.inner.request(method, url),
             client: self.clone(),
-        }
+            extensions: Extensions::new(),
+        };
+        self.initialiser_stack
+            .iter()
+            .fold(req, |req, i| i.init(req))
     }
 
     /// See [`Client::execute`]
@@ -134,6 +168,7 @@ impl From<Client> for ClientWithMiddleware {
         ClientWithMiddleware {
             inner: client,
             middleware_stack: Box::new([]),
+            initialiser_stack: Box::new([]),
         }
     }
 }
@@ -152,6 +187,7 @@ impl fmt::Debug for ClientWithMiddleware {
 pub struct RequestBuilder {
     inner: reqwest::RequestBuilder,
     client: ClientWithMiddleware,
+    extensions: Extensions,
 }
 
 impl RequestBuilder {
@@ -164,14 +200,14 @@ impl RequestBuilder {
     {
         RequestBuilder {
             inner: self.inner.header(key, value),
-            client: self.client,
+            ..self
         }
     }
 
     pub fn headers(self, headers: HeaderMap) -> Self {
         RequestBuilder {
             inner: self.inner.headers(headers),
-            client: self.client,
+            ..self
         }
     }
 
@@ -182,7 +218,7 @@ impl RequestBuilder {
     {
         RequestBuilder {
             inner: self.inner.basic_auth(username, password),
-            client: self.client,
+            ..self
         }
     }
 
@@ -192,49 +228,49 @@ impl RequestBuilder {
     {
         RequestBuilder {
             inner: self.inner.bearer_auth(token),
-            client: self.client,
+            ..self
         }
     }
 
     pub fn body<T: Into<Body>>(self, body: T) -> Self {
         RequestBuilder {
             inner: self.inner.body(body),
-            client: self.client,
+            ..self
         }
     }
 
     pub fn timeout(self, timeout: Duration) -> Self {
         RequestBuilder {
             inner: self.inner.timeout(timeout),
-            client: self.client,
+            ..self
         }
     }
 
     pub fn multipart(self, multipart: Form) -> Self {
         RequestBuilder {
             inner: self.inner.multipart(multipart),
-            client: self.client,
+            ..self
         }
     }
 
     pub fn query<T: Serialize + ?Sized>(self, query: &T) -> Self {
         RequestBuilder {
             inner: self.inner.query(query),
-            client: self.client,
+            ..self
         }
     }
 
     pub fn form<T: Serialize + ?Sized>(self, form: &T) -> Self {
         RequestBuilder {
             inner: self.inner.form(form),
-            client: self.client,
+            ..self
         }
     }
 
     pub fn json<T: Serialize + ?Sized>(self, json: &T) -> Self {
         RequestBuilder {
             inner: self.inner.json(json),
-            client: self.client,
+            ..self
         }
     }
 
@@ -242,22 +278,44 @@ impl RequestBuilder {
         self.inner.build()
     }
 
+    /// Inserts the extension into this request builder
+    pub fn with_extension<T: Send + Sync + 'static>(mut self, extension: T) -> Self {
+        self.extensions.insert(extension);
+        self
+    }
+
+    /// Returns a mutable reference to the internal set of extensions for this request
+    pub fn extensions(&mut self) -> &mut Extensions {
+        &mut self.extensions
+    }
+
     pub async fn send(self) -> Result<Response> {
-        let req = self.inner.build()?;
+        let Self {
-        self.client.execute(req).await
+            inner,
+            client,
+            mut extensions,
+        } = self;
+        let req = inner.build()?;
+        client.execute_with_extensions(req, &mut extensions).await
     }
 
     /// Sends a request with initial [`Extensions`].
+    #[deprecated = "use the with_extension method and send directly"]
     pub async fn send_with_extensions(self, ext: &mut Extensions) -> Result<Response> {
-        let req = self.inner.build()?;
+        let Self { inner, client, .. } = self;
-        self.client.execute_with_extensions(req, ext).await
+        let req = inner.build()?;
+        client.execute_with_extensions(req, ext).await
     }
 
+    // TODO(conradludgate): fix this method to take `&self`. It's currently useless as it is.
+    // I'm tempted to make this breaking change without a major bump, but I'll wait for now
+    #[deprecated = "This method was badly replicated from the base RequestBuilder. If you somehow made use of this method, it will break next major version"]
     pub fn try_clone(self) -> Option<Self> {
-        let client = self.client;
+        self.inner.try_clone().map(|inner| RequestBuilder {
-        self.inner
+            inner,
-            .try_clone()
+            client: self.client,
-            .map(|inner| RequestBuilder { inner, client })
+            extensions: self.extensions,
+        })
     }
 }
 

reqwest-middleware/src/lib.rs

@@ -52,7 +52,9 @@ pub struct ReadmeDoctests;
 mod client;
 mod error;
 mod middleware;
+mod req_init;
 
 pub use client::{ClientBuilder, ClientWithMiddleware, RequestBuilder};
 pub use error::{Error, Result};
 pub use middleware::{Middleware, Next};
+pub use req_init::{Extension, RequestInitialiser};

reqwest-middleware/src/req_init.rs

@@ -0,0 +1,84 @@
+use crate::RequestBuilder;
+
+/// When attached to a [`ClientWithMiddleware`] (generally using [`with_init`]), it is run
+/// whenever the client starts building a request, in the order it was attached.
+///
+/// # Example
+///
+/// ```
+/// use reqwest_middleware::{RequestInitialiser, RequestBuilder};
+///
+/// struct AuthInit;
+///
+/// impl RequestInitialiser for AuthInit {
+///     fn init(&self, req: RequestBuilder) -> RequestBuilder {
+///         req.bearer_auth("my_auth_token")
+///     }
+/// }
+/// ```
+///
+/// [`ClientWithMiddleware`]: crate::ClientWithMiddleware
+/// [`with_init`]: crate::ClientBuilder::with_init
+pub trait RequestInitialiser: 'static + Send + Sync {
+    fn init(&self, req: RequestBuilder) -> RequestBuilder;
+}
+
+impl<F> RequestInitialiser for F
+where
+    F: Send + Sync + 'static + Fn(RequestBuilder) -> RequestBuilder,
+{
+    fn init(&self, req: RequestBuilder) -> RequestBuilder {
+        (self)(req)
+    }
+}
+
+/// A middleware that inserts the value into the [`Extensions`](task_local_extensions::Extensions) during the call.
+///
+/// This is a good way to inject extensions to middleware deeper in the stack
+///
+/// ```
+/// use reqwest::{Client, Request, Response};
+/// use reqwest_middleware::{ClientBuilder, Middleware, Next, Result, Extension};
+/// use task_local_extensions::Extensions;
+///
+/// #[derive(Clone)]
+/// struct LogName(&'static str);
+/// struct LoggingMiddleware;
+///
+/// #[async_trait::async_trait]
+/// impl Middleware for LoggingMiddleware {
+///     async fn handle(
+///         &self,
+///         req: Request,
+///         extensions: &mut Extensions,
+///         next: Next<'_>,
+///     ) -> Result<Response> {
+///         // get the log name or default to "unknown"
+///         let name = extensions
+///             .get()
+///             .map(|&LogName(name)| name)
+///             .unwrap_or("unknown");
+///         println!("[{name}] Request started {req:?}");
+///         let res = next.run(req, extensions).await;
+///         println!("[{name}] Result: {res:?}");
+///         res
+///     }
+/// }
+///
+/// async fn run() {
+///     let reqwest_client = Client::builder().build().unwrap();
+///     let client = ClientBuilder::new(reqwest_client)
+///         .with_init(Extension(LogName("my-client")))
+///         .with(LoggingMiddleware)
+///         .build();
+///     let resp = client.get("https://truelayer.com").send().await.unwrap();
+///     println!("TrueLayer page HTML: {}", resp.text().await.unwrap());
+/// }
+/// ```
+pub struct Extension<T>(pub T);
+
+impl<T: Send + Sync + Clone + 'static> RequestInitialiser for Extension<T> {
+    fn init(&self, req: RequestBuilder) -> RequestBuilder {
+        req.with_extension(self.0.clone())
+    }
+}