feat: various fixes for writing actual projects with the framework

This fixes a lot of stuff found when writing the documentation page:
* Add live reloading middleware
* Add support for response body-modifying middlewares
* Rename reverse_str!() to reverse!() and change param format a bit to
  be more intuitive
* Rename reverse!() to reverse_redirect!() since getting a URL as string
  is far more common than returning a redirect response
* Fixes around error handling, examples, documentation, etc.
* Updated year in LICENSE-MIT

Cargo.toml

@@ -76,6 +76,8 @@ thiserror = "2"
 time = { version = "0.3.35", default-features = false }
 tokio = { version = "1.41", default-features = false }
 tower = "0.5.2"
+# TODO switch back to the published version when https://github.com/leotaku/tower-livereload/pull/24 is released
+tower-livereload = { git = "https://github.com/leotaku/tower-livereload.git", rev = "106cc96f91b11a1eca6d3dfc86be4e766a90a415" }
 tower-sessions = { version = "0.13", default-features = false }
 tracing = { version = "0.1", default-features = false }
 tracing-subscriber = "0.3"

LICENSE-MIT

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2024 Cot Authors
+Copyright (c) 2024-2025 Cot contributors
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

cot/Cargo.toml

@@ -43,6 +43,7 @@ thiserror.workspace = true
 time.workspace = true
 tokio = { workspace = true, features = ["macros", "rt-multi-thread"] }
 tower = { workspace = true, features = ["util"] }
+tower-livereload = { workspace = true, optional = true }
 tower-sessions = { workspace = true, features = ["memory-store"] }
 tracing.workspace = true
 
@@ -67,9 +68,11 @@ ignored = [
 
 [features]
 default = ["sqlite", "postgres", "mysql", "json"]
+full = ["default", "fake", "live-reload"]
 fake = ["dep:fake"]
 db = []
 sqlite = ["db", "sea-query/backend-sqlite", "sea-query-binder/sqlx-sqlite", "sqlx/sqlite"]
 postgres = ["db", "sea-query/backend-postgres", "sea-query-binder/sqlx-postgres", "sqlx/postgres"]
 mysql = ["db", "sea-query/backend-mysql", "sea-query-binder/sqlx-mysql", "sqlx/mysql"]
 json = ["serde_json"]
+live-reload = ["dep:tower-livereload"]

cot/src/admin.rs

@@ -18,7 +18,7 @@ use crate::forms::{
 use crate::request::{Request, RequestExt};
 use crate::response::{Response, ResponseExt};
 use crate::router::Router;
-use crate::{reverse, static_files, Body, CotApp, Render, StatusCode};
+use crate::{reverse_redirect, static_files, Body, CotApp, Render, StatusCode};
 
 #[derive(Debug, Form)]
 struct LoginForm {
@@ -60,7 +60,7 @@ async fn index(mut request: Request) -> cot::Result<Response> {
             Body::fixed(template.render()?),
         ))
     } else {
-        Ok(reverse!(request, "login"))
+        Ok(reverse_redirect!(request, "login"))
     }
 }
 
@@ -72,7 +72,7 @@ async fn login(mut request: Request) -> cot::Result<Response> {
         match login_form {
             FormResult::Ok(login_form) => {
                 if authenticate(&mut request, login_form).await? {
-                    return Ok(reverse!(request, "index"));
+                    return Ok(reverse_redirect!(request, "index"));
                 }
 
                 let mut context = LoginForm::build_context(&mut request).await?;
@@ -139,7 +139,7 @@ async fn view_model(mut request: Request) -> cot::Result<Response> {
             Body::fixed(template.render()?),
         ))
     } else {
-        Ok(reverse!(request, "login"))
+        Ok(reverse_redirect!(request, "login"))
     }
 }
 

cot/src/error.rs

@@ -26,6 +26,14 @@ impl Error {
         }
     }
 
+    #[must_use]
+    pub fn custom<E>(error: E) -> Self
+    where
+        E: Into<Box<dyn std::error::Error + Send + Sync + 'static>>,
+    {
+        Self::new(ErrorRepr::Custom(error.into()))
+    }
+
     #[must_use]
     pub(crate) fn backtrace(&self) -> &CotBacktrace {
         &self.backtrace
@@ -78,13 +86,16 @@ impl_error_from_repr!(serde_json::Error);
 #[derive(Debug, Error)]
 #[non_exhaustive]
 pub(crate) enum ErrorRepr {
+    /// A custom user error occurred.
+    #[error("{0}")]
+    Custom(#[source] Box<dyn std::error::Error + Send + Sync>),
     /// An error occurred while trying to start the server.
     #[error("Could not start server: {source}")]
     StartServer { source: std::io::Error },
     /// An error occurred while trying to read the request body.
     #[error("Could not retrieve request body: {source}")]
     ReadRequestBody {
-        #[from]
+        #[source]
         source: Box<dyn std::error::Error + Send + Sync>,
     },
     /// The request body had an invalid `Content-Type` header.
@@ -120,6 +131,12 @@ pub(crate) enum ErrorRepr {
     #[error("JSON error: {0}")]
     #[cfg(feature = "json")]
     JsonError(#[from] serde_json::Error),
+    /// An error occurred inside a middleware-wrapped view.
+    #[error("{source}")]
+    MiddlewareWrapped {
+        #[source]
+        source: Box<dyn std::error::Error + Send + Sync>,
+    },
 }
 
 #[cfg(test)]

cot/src/error_page.rs

@@ -301,7 +301,7 @@ fn build_cot_failure_page() -> axum::response::Response {
     axum::response::Response::builder()
         .status(StatusCode::INTERNAL_SERVER_ERROR)
         .body(axum::body::Body::from(FAILURE_PAGE))
-        .expect("Building the Cot failure page should not fail")
+        .expect("Building the Cot failure page should never fail")
 }
 
 thread_local! {
@@ -310,7 +310,6 @@ thread_local! {
 }
 
 pub(super) fn error_page_panic_hook(info: &PanicHookInfo<'_>) {
-    // TODO print out the panic as well
     let location = info.location().map(|location| format!("{location}"));
     PANIC_LOCATION.replace(location);