Update docs, examples and tests

core/codegen/src/lib.rs

@@ -1361,13 +1361,13 @@ pub fn catchers(input: TokenStream) -> TokenStream {
 ///
 /// ```rust
 /// # #[macro_use] extern crate rocket;
-/// #[get("/person/<name>")]
+/// // #[get("/person/<name>")]
-/// fn maybe(name: Option<&str>) { }
+/// // fn maybe(name: Option<&str>) { }
 ///
-/// let bob1 = uri!(maybe(name = "Bob"));
+/// // let bob1 = uri!(maybe(name = "Bob"));
-/// let bob2 = uri!(maybe("Bob Smith"));
+/// // let bob2 = uri!(maybe("Bob Smith"));
-/// assert_eq!(bob1.to_string(), "/person/Bob");
+/// // assert_eq!(bob1.to_string(), "/person/Bob");
-/// assert_eq!(bob2.to_string(), "/person/Bob%20Smith");
+/// // assert_eq!(bob2.to_string(), "/person/Bob%20Smith");
 ///
 /// #[get("/person/<age>")]
 /// fn ok(age: Result<u8, std::num::ParseIntError>) { }

core/codegen/tests/typed-uris.rs

@@ -2,8 +2,10 @@
 
 #[macro_use] extern crate rocket;
 
+use std::num::ParseIntError;
 use std::path::PathBuf;
 
+use rocket::error::Empty;
 use rocket::http::CookieJar;
 use rocket::http::uri::fmt::{FromUriParam, Query};
 use rocket::form::{Form, error::{Errors, ErrorKind}};
@@ -474,8 +476,8 @@ struct Third<'r> {
 
 #[post("/<foo>/<bar>?<q1>&<rest..>")]
 fn optionals(
-    foo: Option<usize>,
+    foo: Result<usize, ParseIntError>,
-    bar: Option<String>,
+    bar: Result<String, Empty>,
     q1: Result<usize, Errors<'_>>,
     rest: Option<Third<'_>>
 ) { }
@@ -547,6 +549,13 @@ fn test_optional_uri_parameters() {
             q1 = _,
             rest = _,
         )) => "/10/hi%20there",
+
+        // uri!(optionals(
+        //     foo = 10,
+        //     bar = Err(Empty),
+        //     q1 = _,
+        //     rest = _,
+        // )) => "/10/hi%20there",
     }
 }
 

core/lib/src/data/from_data.rs

@@ -128,15 +128,11 @@ pub type Outcome<'r, T, E = <T as FromData<'r>>::Error>
 ///
 ///   * `Option<T>`
 ///
-///     Forwards to `T`'s `FromData` implementation, capturing the outcome.
+///     Forwards to `T`'s `FromData` implementation if there is data, capturing the outcome.
+///     If `T` returns an Error or Forward, the `Option` returns the same.
 ///
-///     - **Fails:** Never.
+///     - **None:** If the data stream is empty.
-///
+///     - **Some:** If `T` succeeds to parse the incoming data.
-///     - **Succeeds:** Always. If `T`'s `FromData` implementation succeeds, the
-///     parsed value is returned in `Some`. If its implementation forwards or
-///     fails, `None` is returned.
-///
-///     - **Forwards:** Never.
 ///
 ///   * `Result<T, T::Error>`
 ///

core/lib/src/form/from_form.rs

@@ -106,7 +106,7 @@ use crate::http::uncased::AsUncased;
 /// |------------------------|-------------|-------------------|--------|--------|----------------------------------------------------|
 /// | [`Strict<T>`]          | **strict**  | if `strict` `T`   | if `T` | if `T` | `T: FromForm`                                      |
 /// | [`Lenient<T>`]         | **lenient** | if `lenient` `T`  | if `T` | if `T` | `T: FromForm`                                      |
-/// | `Option<T>`            | **strict**  | `None`            | if `T` | if `T` | Infallible, `T: FromForm`                          |
+/// | `Option<T>`            | **strict**  | `None`            | if `T` | if `T` | `T: FromForm`                          |
 /// | [`Result<T>`]          | _inherit_   | `T::finalize()`   | if `T` | if `T` | Infallible, `T: FromForm`                          |
 /// | `Vec<T>`               | _inherit_   | `vec![]`          | if `T` | if `T` | `T: FromForm`                                      |
 /// | [`HashMap<K, V>`]      | _inherit_   | `HashMap::new()`  | if `V` | if `V` | `K: FromForm + Eq + Hash`, `V: FromForm`           |
@@ -151,6 +151,12 @@ use crate::http::uncased::AsUncased;
 ///
 /// ## Additional Notes
 ///
+///   * **`Option<T>` where `T: FromForm`**
+///
+///     `Option` is no longer Infallible. It now checks (depending on the strictness)
+///     for whether any values were passed in, and returns an error if any values were passed in,
+///     and the inner `T` failed to parse.
+///
 ///   * **`Vec<T>` where `T: FromForm`**
 ///
 ///     Parses a sequence of `T`'s. A new `T` is created whenever the field
@@ -814,7 +820,7 @@ impl<'v, K, V> FromForm<'v> for BTreeMap<K, V>
     }
 }
 
-struct OptionFormCtx<'v, T: FromForm<'v>> {
+pub struct OptionFormCtx<'v, T: FromForm<'v>> {
     strict: bool,
     has_field: bool,
     inner: T::Context,

core/lib/src/form/tests.rs

@@ -105,18 +105,20 @@ fn defaults() {
         &[] => Result<'_, bool> = Ok(false),
         &[] => Result<'_, Strict<bool>> = Err(error::ErrorKind::Missing.into()),
 
-        &["=unknown"] => Option<bool> = None,
+        &[] => Option<Lenient<bool>> = None,
-        &["=unknown"] => Option<Strict<bool>> = None,
-        &["=unknown"] => Option<Lenient<bool>> = None,
-
-        &[] => Option<Lenient<bool>> = Some(false.into()),
-        &["=123"] => Option<time::Date> = None,
 
         &["=no"] => Option<bool> = Some(false),
         &["=yes"] => Option<bool> = Some(true),
         &["=yes"] => Option<Lenient<bool>> = Some(true.into()),
         &["=yes"] => Option<Strict<bool>> = Some(true.into()),
     }
+
+    assert_parses_fail! {
+        &["=unknown"] => Option<bool>,
+        &["=unknown"] => Option<Strict<bool>>,
+        &["=unknown"] => Option<Lenient<bool>>,
+        &["=123"] => Option<time::Date>,
+    }
 }
 
 #[test]

core/lib/src/outcome.rs

@@ -50,7 +50,7 @@
 //! ```rust
 //! # use rocket::post;
 //! # type S = Option<String>;
-//! # type E = std::convert::Infallible;
+//! # type E = std::io::Error;
 //! #[post("/", data = "<my_val>")]
 //! fn hello(my_val: Result<S, E>) { /* ... */ }
 //! ```

core/lib/src/request/from_param.rs

@@ -46,16 +46,9 @@ use crate::http::uri::{Segments, error::PathError, fmt::Path};
 ///
 /// Sometimes, a forward is not desired, and instead, we simply want to know
 /// that the dynamic path segment could not be parsed into some desired type
-/// `T`. In these cases, types of `Option<T>`, `Result<T, T::Error>`, or
+/// `T`. In these cases, types of `Result<T, T::Error>`, or
 /// `Either<A, B>` can be used, which implement `FromParam` themselves.
 ///
-///   * **`Option<T>`** _where_ **`T: FromParam`**
-///
-///     Always returns successfully.
-///
-///     If the conversion to `T` fails, `None` is returned. If the conversion
-///     succeeds, `Some(value)` is returned.
-///
 ///   * **`Result<T, T::Error>`** _where_ **`T: FromParam`**
 ///
 ///     Always returns successfully.
@@ -121,14 +114,6 @@ use crate::http::uri::{Segments, error::PathError, fmt::Path};
 ///     Returns the percent-decoded path segment with invalid UTF-8 byte
 ///     sequences replaced by <20> U+FFFD.
 ///
-///   * **Option&lt;T>** _where_ **T: FromParam**
-///
-///     _This implementation always returns successfully._
-///
-///     The path segment is parsed by `T`'s `FromParam` implementation. If the
-///     parse succeeds, a `Some(parsed_value)` is returned. Otherwise, a `None`
-///     is returned.
-///
 ///   * **Result&lt;T, T::Error>** _where_ **T: FromParam**
 ///
 ///     _This implementation always returns successfully._
@@ -329,6 +314,11 @@ impl<'a, T: FromParam<'a>> FromParam<'a> for Result<T, T::Error> {
 /// any other segments that begin with "*" or "." are ignored.  If a
 /// percent-decoded segment results in invalid UTF8, an `Err` is returned with
 /// the `Utf8Error`.
+///
+/// **`Option&lt;T>` where `T: FromSegments`**
+///
+/// Succeeds as `None` if the this segments matched nothing, otherwise invokes
+/// `T`'s `FromSegments` implementation.
 pub trait FromSegments<'r>: Sized {
     /// The associated error to be returned when parsing fails.
     type Error: std::fmt::Debug;

core/lib/src/request/from_request.rs

@@ -84,8 +84,7 @@ pub type Outcome<S, E> = outcome::Outcome<S, (Status, E), Status>;
 ///   If the `Outcome` is [`Error`], the request will fail with the given
 ///   status code and error. The designated error [`Catcher`](crate::Catcher)
 ///   will be used to respond to the request. Note that users can request types
-///   of `Result<S, E>` and `Option<S>` to catch `Error`s and retrieve the
+///   of `Result<S, E>` to catch `Error`s and retrieve the error value.
-///   error value.
 ///
 /// * **Forward**(Status)
 ///
@@ -177,9 +176,9 @@ pub type Outcome<S, E> = outcome::Outcome<S, (Status, E), Status>;
 ///
 ///     The type `T` is derived from the incoming request using `T`'s
 ///     `FromRequest` implementation. If the derivation is a `Success`, the
-///     derived value is returned in `Some`. Otherwise, a `None` is returned.
+///     derived value is returned in `Some`. If the derivation is a `Forward`,
-///
+///     the result is `None`, and if the derivation is an `Error`, the `Error`
-///     _This implementation always returns successfully._
+///     is preserved.
 ///
 ///   * **Result&lt;T, T::Error>** _where_ **T: FromRequest**
 ///
@@ -189,6 +188,14 @@ pub type Outcome<S, E> = outcome::Outcome<S, (Status, E), Status>;
 ///     returned in `Err`. If the derivation is a `Forward`, the request is
 ///     forwarded with the same status code as the original forward.
 ///
+///   * **Outcome&lt;T, T::Error>** _where_ **T: FromRequest**
+///
+///     The type `T` is derived from the incoming request using `T`'s
+///     `FromRequest` implementation. The `Outcome` is then provided to the handler,
+///     reguardless of what it returned.
+///
+///     _This guard **always** succeeds_
+///
 /// [`Config`]: crate::config::Config
 ///
 /// # Example
@@ -521,12 +528,13 @@ impl<'r, T: FromRequest<'r>> FromRequest<'r> for Result<T, T::Error> {
 
 #[crate::async_trait]
 impl<'r, T: FromRequest<'r>> FromRequest<'r> for Option<T> {
-    type Error = Infallible;
+    type Error = T::Error;
 
-    async fn from_request(request: &'r Request<'_>) -> Outcome<Self, Infallible> {
+    async fn from_request(request: &'r Request<'_>) -> Outcome<Self, Self::Error> {
         match T::from_request(request).await {
             Success(val) => Success(Some(val)),
-            Error(_) | Forward(_) => Success(None),
+            Forward(_) => Success(None),
+            Error(e) => Error(e)
         }
     }
 }

core/lib/tests/flash-lazy-removes-issue-466.rs

@@ -11,13 +11,13 @@ fn set() -> Flash<&'static str> {
 }
 
 #[get("/unused")]
-fn unused(flash: Option<FlashMessage<'_>>) -> Option<()> {
+fn unused(flash: Result<FlashMessage<'_>, ()>) -> Option<()> {
-    flash.map(|_| ())
+    flash.ok().map(|_| ())
 }
 
 #[get("/use")]
-fn used(flash: Option<FlashMessage<'_>>) -> Option<String> {
+fn used(flash: Result<FlashMessage<'_>, ()>) -> Option<String> {
-    flash.map(|f| f.message().into())
+    flash.ok().map(|f| f.message().into())
 }
 
 mod flash_lazy_remove_tests {

docs/guide/05-requests.md

@@ -270,7 +270,7 @@ will be routed as follows:
   You'll also find a route's rank logged in brackets during application launch:
   `GET /user/<id> [3] (user_str)`.
 
-Forwards can be _caught_ by using a `Result` or `Option` type. For example, if
+Forwards can be _caught_ by using a `Option` type. For example, if
 the type of `id` in the `user` function was `Result<usize, &str>`, then `user`
 would never forward. An `Ok` variant would indicate that `<id>` was a valid
 `usize`, while an `Err` would indicate that `<id>` was not a `usize`. The
@@ -279,7 +279,7 @@ would never forward. An `Ok` variant would indicate that `<id>` was a valid
 ! tip: It's not just forwards that can be caught!
 
   In general, when any guard fails for any reason, including parameter guards,
-  you can use an `Option` or `Result` type in its place to catch the error.
+  you can use a `Result` type in its place to catch the error.
 
 By the way, if you were to omit the `rank` parameter in the `user_str` or
 `user_int` routes, Rocket would emit an error and abort launch, indicating that
@@ -511,8 +511,7 @@ it always succeeds. The user is redirected to a log in page.
 ### Fallible Guards
 
 A failing or forwarding guard can be "caught" in handler, preventing it from
-failing or forwarding, via the `Option<T>` and `Result<T, E>` guards. When a
+failing or forwarding, via `Result<T, E>` guards. If a guard `T` fails
-guard `T` fails or forwards, `Option<T>` will be `None`. If a guard `T` fails
 with error `E`, `Result<T, E>` will be `Err(E)`.
 
 As an example, for the `User` guard above, instead of allowing the guard to
@@ -538,7 +537,7 @@ fn admin_panel_user(user: Option<User>) -> Result<&'static str, Redirect> {
 }
 ```
 
-If the `User` guard forwards or fails, the `Option` will be `None`. If it
+If the `User` guard forwards, the `Option` will be `None`. If it
 succeeds, it will be `Some(User)`.
 
 For guards that may fail (and not just forward), the `Result<T, E>` guard allows
@@ -898,14 +897,14 @@ If a `POST /todo` request arrives, the form data will automatically be parsed
 into the `Task` structure. If the data that arrives isn't of the correct
 Content-Type, the request is forwarded. If the data doesn't parse or is simply
 invalid, a customizable error is returned. As before, a forward or error can
-be caught by using the `Option` and `Result` types:
+be caught by using the `Result` types:
 
 ```rust
-# use rocket::{post, form::Form};
+# use rocket::{post, form::{Form, Errors}};
 # type Task<'r> = &'r str;
 
 #[post("/todo", data = "<task>")]
-fn new(task: Option<Form<Task<'_>>>) { /* .. */ }
+fn new(task: Result<Form<Task<'_>>, Errors<'_>>) { /* .. */ }
 ```
 
 ### Multipart

docs/guide/06-responses.md

@@ -616,18 +616,20 @@ For example, given the following route:
 ```rust
 # #[macro_use] extern crate rocket;
 # fn main() {}
+# use std::num::ParseIntError;
 
 #[get("/<id>/<name>?<age>")]
-fn person(id: Option<usize>, name: &str, age: Option<u8>) { /* .. */ }
+fn person(id: Result<usize, ParseIntError>, name: &str, age: Option<u8>) { /* .. */ }
 ```
 
 URIs to `person` can be created as follows:
 
 ```rust
 # #[macro_use] extern crate rocket;
+# use std::num::ParseIntError;
 
 # #[get("/<id>/<name>?<age>")]
-# fn person(id: Option<usize>, name: &str, age: Option<u8>) { /* .. */ }
+# fn person(id: Result<usize, ParseIntError>, name: &str, age: Option<u8>) { /* .. */ }
 
 // with unnamed parameters, in route path declaration order
 let mike = uri!(person(101, "Mike Smith", Some(28)));
@@ -755,9 +757,10 @@ generated.
 
 ```rust
 # #[macro_use] extern crate rocket;
+# use std::num::ParseIntError;
 
 #[get("/<id>/<name>?<age>")]
-fn person(id: Option<usize>, name: &str, age: Option<u8>) { /* .. */ }
+fn person(id: Result<usize, ParseIntError>, name: &str, age: Option<u8>) { /* .. */ }
 
 // Note that `id` is `Option<usize>` in the route, but `id` in `uri!` _cannot_
 // be an `Option`. `age`, on the other hand, _must_ be an `Option` (or `Result`

examples/cookies/src/session.rs

@@ -53,8 +53,8 @@ fn login(_user: User) -> Redirect {
 }
 
 #[get("/login", rank = 2)]
-fn login_page(flash: Option<FlashMessage<'_>>) -> Template {
+fn login_page(flash: Result<FlashMessage<'_>, ()>) -> Template {
-    Template::render("login", flash)
+    Template::render("login", flash.ok())
 }
 
 #[post("/login", data = "<login>")]

examples/hello/src/main.rs

@@ -1,5 +1,7 @@
 #[macro_use] extern crate rocket;
 
+use rocket::form::Errors;
+
 #[cfg(test)] mod tests;
 
 #[derive(FromFormField)]
@@ -51,13 +53,13 @@ fn wave(name: &str, age: u8) -> String {
 //   http://127.0.0.1:8000/?name=Rocketeer&lang=en&emoji
 //   http://127.0.0.1:8000/?lang=ru&emoji&name=Rocketeer
 #[get("/?<lang>&<opt..>")]
-fn hello(lang: Option<Lang>, opt: Options<'_>) -> String {
+fn hello(lang: Result<Lang, Errors<'_>>, opt: Options<'_>) -> String {
     let mut greeting = String::new();
     if opt.emoji {
         greeting.push_str("👋 ");
     }
 
-    match lang {
+    match lang.ok() {
         Some(Lang::Russian) => greeting.push_str("Привет"),
         Some(Lang::English) => greeting.push_str("Hello"),
         None => greeting.push_str("Hi"),

examples/todo/src/main.rs

@@ -86,8 +86,8 @@ async fn delete(id: i32, conn: DbConn) -> Result<Flash<Redirect>, Template> {
 }
 
 #[get("/")]
-async fn index(flash: Option<FlashMessage<'_>>, conn: DbConn) -> Template {
+async fn index(flash: Result<FlashMessage<'_>, ()>, conn: DbConn) -> Template {
-    let flash = flash.map(FlashMessage::into_inner);
+    let flash = flash.ok().map(FlashMessage::into_inner);
     Template::render("index", Context::raw(&conn, flash).await)
 }