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use crate::{errors::*, reactor::Reactor};
#[cfg(engine)]
use crate::{i18n::Translator, reactor::RenderMode, state::TemplateState};
use fmterr::fmt_err;
use serde::{Deserialize, Serialize};
#[cfg(any(client, doc))]
use std::sync::Arc;
#[cfg(engine)]
use sycamore::prelude::create_scope_immediate;
#[cfg(any(client, doc))]
use sycamore::prelude::{create_child_scope, try_use_context, ScopeDisposer};
use sycamore::{
prelude::{view, Scope},
utils::hydrate::with_no_hydration_context,
view::View,
web::{Html, SsrNode},
};
/// The error handling system of an app. In Perseus, errors come in several
/// forms, all of which must be handled. This system provides a way to do this
/// automatically, maximizing your app's error tolerance, including against
/// panics.
pub struct ErrorViews<G: Html> {
/// The central function that parses the error provided and returns a tuple
/// of views to deal with it: the first view is the document metadata,
/// and the second the body of the error.
#[allow(clippy::type_complexity)]
handler: Box<
dyn Fn(Scope, ClientError, ErrorContext, ErrorPosition) -> (View<SsrNode>, View<G>)
+ Send
+ Sync,
>,
/// A function for determining if a subsequent load error should occupy the
/// entire page or not. If this returns `true`, the whole page will be
/// taken over (e.g. for a 404), but, if it returns `false`, a small
/// popup will be created on the current page (e.g. for an internal
/// error unrelated to the page itself).
///
/// This is left to user discretion in the case of subsequent loads. For
/// initial loads, we will render a page-wide error only if it came from
/// the engine, otherwise just a popup over the prerendered content so
/// the user can proceed with visibility, but not interactivity.
subsequent_load_determinant: Box<dyn Fn(&ClientError) -> bool + Send + Sync>,
/// A verbatim copy of the user's handler, intended for panics. This is
/// needed because we have to extract it completely and give it to the
/// standard library in a thread-safe manner (even though Wasm is
/// single-threaded).
///
/// This will be extracted by the `PerseusApp` creation process and put in a
/// place where it can be safely extracted. The replacement function
/// will panic if called, so this should **never** be manually executed.
#[cfg(any(client, doc))]
#[allow(clippy::type_complexity)]
panic_handler: Arc<
dyn Fn(Scope, ClientError, ErrorContext, ErrorPosition) -> (View<SsrNode>, View<G>)
+ Send
+ Sync,
>,
}
impl<G: Html> std::fmt::Debug for ErrorViews<G> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("ErrorViews").finish_non_exhaustive()
}
}
impl<G: Html> ErrorViews<G> {
/// Creates an error handling system for your app with the given handler
/// function. This will be provided a [`ClientError`] to match against,
/// along with an [`ErrorContext`], which tells you what you have available
/// to you (since, in some critical errors, you might not even have a
/// translator).
///
/// The function given to this should return a tuple of two `View`s: the
/// first to be placed in document `<head>`, and the second
/// for the body. For views with `ErrorPosition::Popup` or
/// `ErrorPosition::Widget`, the head view will be ignored,
/// and would usually be returned as `View::empty()`.
pub fn new(
handler: impl Fn(Scope, ClientError, ErrorContext, ErrorPosition) -> (View<SsrNode>, View<G>)
+ Send
+ Sync
+ Clone
+ 'static,
) -> Self {
#[allow(clippy::redundant_clone)]
Self {
handler: Box::new(handler.clone()),
// Sensible defaults are fine here
subsequent_load_determinant: Box::new(|err| {
match err {
// Any errors from the server should take up the whole page
ClientError::ServerError { .. } => true,
// Anything else is internal-ish (e.g. a fetch failure would be a network
// failure, so we keep the user where they are)
_ => false,
}
}),
#[cfg(any(client, doc))]
panic_handler: Arc::new(handler),
}
}
/// Sets the function that determines if an error on a *subsequent load*
/// should be presented to the user as taking up the whole page, or just
/// being in a little popup. Usually, you can leave this as the default,
/// which will display any internal errors as popups, and any errors from
/// the server (e.g. a 404 not found) as full pages.
///
/// You could use this to create extremely unorthodox patterns like
/// rendering a popup on the current page if the user clicks a link that
/// goes to a 404, if you really wanted.
///
/// For widgets, returning `true` from the function you provide to this will
/// take up the whole widget, as opposed to the whole page.
///
/// *Note: if you want all your errors to take up the whole page no matter
/// what (not recommended, see the book for why!), you should leave this
/// function as the default and simply style `#__perseus_error_popup` to
/// take up the whole page.*
pub fn subsequent_load_determinant_fn(
&mut self,
val: impl Fn(&ClientError) -> bool + Send + Sync + 'static,
) -> &mut Self {
self.subsequent_load_determinant = Box::new(val);
self
}
/// Returns `true` if the given error, which must have occurred during a
/// subsequent load, should be displayed as a popup, as opposed to
/// occupying the entire page/widget.
#[cfg(any(client, doc))]
pub(crate) fn subsequent_err_should_be_popup(&self, err: &ClientError) -> bool {
!(self.subsequent_load_determinant)(err)
}
/// Force-sets the unlocalized defaults. If you really want to use the
/// default error pages in production, this will allow you to (where
/// they would normally fail if you simply specified nothing).
///
/// **Warning:** these defaults are completely unlocalized, unstyled, and
/// intended for development! You will be able to use these by not
/// specifying any `.error_views()` on your `PerseusApp` in development,
/// and you should only use this function if you're doing production
/// testing of Perseus, and you don't particularly want to write
/// your own error pages.
///
/// Note that this is used throughout the Perseus examples for brevity.
pub fn unlocalized_development_default() -> Self {
// Because this is an unlocalized, extremely simple default, we don't care about
// capabilities or positioning
Self::new(|cx, err, _, pos| {
match err {
// Special case for 404 due to its frequency
ClientError::ServerError { status, .. } if status == 404 => (
view! { cx,
title { "Page not found" }
},
view! { cx,
div(
style = r#"
display: flex;
justify-content: center;
align-items: center;
height: 95vh;
width: 100%;
"#
) {
main(
style = r#"
display: flex;
flex-direction: column;
border: 1px solid black;
border-radius: 0.5rem;
max-width: 36rem;
margin: 1rem;
"#
) {
h3(
style = r#"
font-size: 1.5rem;
line-height: 2rem;
font-weight: 700;
width: 100%;
padding-bottom: 1rem;
border-bottom: 1px solid black;
margin-top: 1rem;
margin-bottom: 1rem;
"#
) {
span(style = "padding-left: 1rem;") { "Page not found!" }
}
div(
style = r#"
padding: 1rem;
padding-top: 0;
margin-top: 1rem;
margin-bottom: 1rem;
"#
) {
span {
"Uh-oh, that page doesn't seem to exist! Perhaps you forgot to add it to your "
code { "PerseusApp" }
"?"
}
}
}
}
},
),
ClientError::Panic(panic_msg) => (
// Panics are popups
View::empty(),
view! { cx,
div(
style = r#"
position: fixed;
bottom: 0;
right: 0;
background-color: #f87171;
color: white;
margin: 1rem;
border-radius: 0.5rem;
max-width: 30rem;
"#
) {
h2(
style = r#"
font-size: 1.5rem;
line-height: 2rem;
font-weight: 700;
width: 100%;
padding-bottom: 1rem;
border-bottom: 1px solid white;
margin-top: 1rem;
margin-bottom: 1rem;
"#
) {
span(style = "padding-left: 1rem;") { "Critical error!" }
}
div(
style = r#"
padding: 1rem;
padding-top: 0;
margin-top: 1rem;
"#
) {
p { "Your app has panicked! You can see the panic message below." }
pre(
style = r#"
background-color: #f59e0b;
padding: 1rem;
margin-top: 1rem;
border-radius: 0.5rem;
white-space: pre-wrap;
word-wrap: break-word;
"#
) {
(panic_msg)
}
// This can happen with HSR, and it's a good idea to help the user out a bit
// TODO Should there be more hints here?
(if panic_msg.contains("cannot modify the panic hook from a panicking thread") {
view! { cx,
p {
i { "It looks like the error is about the panicking hook itself, which means the original panic has been overidden, possibly by hot state reloading in development. Reloading the page might show you the original panic message." }
}
}
} else {
View::empty()
})
}
}
},
),
err => {
let err_msg = fmt_err(&err);
// This will be placed in either a popup or across the page
let inner_view = view! { cx,
div(
style = r#"
background-color: #f87171;
color: white;
margin: 1rem;
border-radius: 0.5rem;
max-width: 30rem;
"#
) {
h2(
style = r#"
font-size: 1.5rem;
line-height: 2rem;
font-weight: 700;
width: 100%;
padding-bottom: 1rem;
border-bottom: 1px solid white;
margin-top: 1rem;
margin-bottom: 1rem;
"#
) {
span(style = "padding-left: 1rem;") { "Error!" }
}
div(
style = r#"
padding: 1rem;
padding-top: 0;
margin-top: 1rem;
"#
) {
p { "Your app encountered an error, you can see the details below." }
pre(
style = r#"
background-color: #f59e0b;
padding: 1rem;
margin-top: 1rem;
border-radius: 0.5rem;
white-space: pre-wrap;
word-break: break-word;
"#
) {
(err_msg)
}
}
}
};
(
view! { cx,
title { "Error" }
},
match pos {
ErrorPosition::Page => view! { cx,
div(
style = r#"
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
height: 95vh;
width: 100%;
"#
) {
(inner_view)
}
},
ErrorPosition::Popup => view! { cx,
div(
style = r#"
position: fixed;
bottom: 0;
right: 0;
display: flex;
justify-content: center;
align-items: center;
"#
) {
(inner_view)
}
},
ErrorPosition::Widget => view! { cx,
div(
style = r#"
display: flex;
flex-direction: column;
"#
) {
(inner_view)
}
},
},
)
}
}
})
}
}
#[cfg(any(client, doc))]
impl<G: Html> ErrorViews<G> {
/// Invokes the user's handling function, producing head/body views for the
/// given error. From the given scope, this will determine the
/// conditions under which the error can be rendered.
pub(crate) fn handle<'a>(
&self,
cx: Scope<'a>,
err: ClientError,
pos: ErrorPosition,
) -> (String, View<G>, ScopeDisposer<'a>) {
let reactor = try_use_context::<Reactor<G>>(cx);
// From the given scope, we can perfectly determine the capabilities this error
// view will have
let info = match reactor {
Some(reactor) => match reactor.try_get_translator() {
Some(_) => ErrorContext::Full,
None => ErrorContext::WithReactor,
},
None => ErrorContext::Static,
};
let mut body_view = View::empty();
let mut head_str = String::new();
let disposer = create_child_scope(cx, |child_cx| {
let (head_view, body_view_local) = (self.handler)(child_cx, err, info, pos);
body_view = body_view_local;
// Stringify the head view with no hydration markers
head_str = sycamore::render_to_string(|_| with_no_hydration_context(|| head_view));
});
(head_str, body_view, disposer)
}
/// Extracts the panic handler from within the error views. This should
/// generally only be called by `PerseusApp`'s error views instantiation
/// system.
#[allow(clippy::type_complexity)]
pub(crate) fn take_panic_handler(
&mut self,
) -> Arc<
dyn Fn(Scope, ClientError, ErrorContext, ErrorPosition) -> (View<SsrNode>, View<G>)
+ Send
+ Sync,
> {
std::mem::replace(
&mut self.panic_handler,
Arc::new(|_, _, _, _| unreachable!()),
)
}
}
#[cfg(engine)]
impl ErrorViews<SsrNode> {
/// Renders an error view on the engine-side. This takes an optional
/// translator. This will return a tuple of `String`ified views for the
/// head and body. For widget errors, the former should be discarded.
///
/// Since the only kind of error that can be sent from the server to the
/// client falls under a `ClientError::ServerError`, which always takes
/// up the whole page, and since we presumably don't have any actual
/// content to render, this will, expectedly, take up the whole page.
///
/// This cannot be used for widgets (use `.handle_widget()` instead).
///
/// # Hydration
///
/// At present, due to the difficulties of controlling hydration contexts
/// in a fine-grained manner, Perseus does not hydrate error views
/// whatsoever. This is compounded by the problem of exported error
/// views, which do not have access to locales, whereas their
/// browser-side-rendered counterparts do. To avoid hydration mismatches
/// and unnecessary development panics, hydration is therefore disabled
/// for error views.
pub(crate) fn render_to_string(
&self,
err: ServerErrorData,
translator: Option<&Translator>,
) -> (String, String) {
// We need to create an engine-side reactor
let reactor =
Reactor::<SsrNode>::engine(TemplateState::empty(), RenderMode::Error, translator);
let mut body_str = String::new();
let mut head_str = String::new();
create_scope_immediate(|cx| {
reactor.add_self_to_cx(cx);
// Depending on whether or not we had a translator, we can figure out the
// capabilities
let err_cx = match translator {
// On the engine-side, we don't get global state (see docs for
// `ErrorContext::FullNoGlobal`)
Some(_) => ErrorContext::FullNoGlobal,
None => ErrorContext::WithReactor,
};
// NOTE: No hydration context
let (head_view, body_view) = (self.handler)(
cx,
ClientError::ServerError {
status: err.status,
message: err.msg,
},
err_cx,
ErrorPosition::Page,
);
head_str = sycamore::render_to_string(|_| with_no_hydration_context(|| head_view));
body_str = sycamore::render_to_string(|_| body_view);
});
(head_str, body_str)
}
}
impl<G: Html> ErrorViews<G> {
/// Renders an error view for the given widget, using the given scope. This
/// will *not* create a new child scope, it will simply use the one it is
/// given.
///
/// Since this only handles widgets, it will automatically discard the head.
///
/// This assumes the reactor has already been fully set up with a translator
/// on the given context, and hence this will always use
/// `ErrorContext::Full` (since widgets should not be rendered if a
/// translator cannot be found, and certainly not if a reactor could not
/// be instantiated).
pub(crate) fn handle_widget(&self, err: ClientError, cx: Scope) -> View<G> {
let (_head, body) = (self.handler)(cx, err, ErrorContext::Full, ErrorPosition::Widget);
body
}
}
/// The context of an error, which determines what is available to your views.
/// This *must* be checked before using things like translators, which may not
/// be available, depending on the information in here.
#[derive(Debug, Clone, Copy)]
pub enum ErrorContext {
/// Perseus has suffered an unrecoverable error in initialization, and
/// routing/interactivity is impossible. Your error view will be
/// rendered to the page, and then Perseus will terminate completely.
/// This means any buttons, handlers, etc. *will not run*!
///
/// If you're having trouble with this, imagine printing out your error
/// view. That's the amount of functionality you get (except that the
/// browser will automatically take over any links). If you want
/// interactivity, you *could* use `dangerously_set_inner_html` to create
/// some JS handlers, for instance for offering the user a button to
/// reload the page.
Static,
/// Perseus suffered an error before it was able to create a translator.
/// Your error view will be rendered inside a proper router, and you'll
/// have a [`Reactor`] available in context, but using the `t!` or
/// `link!` macros will lead to a panic. If you present links to other pages
/// in the app, the user will be able to press them, and these will try
/// to set up a translator, but this may fail.
///
/// If your app doesn't use internationalization, Perseus does still have a
/// dummy translator internally, so this doesn't completely evaporate,
/// but you can ignore it.
///
/// *Note: currently, if the user goes to, say
/// `/en-US/this-page-does-not-exist`, even though the page is clearly
/// localized, Perseus will not provide a translator. This will be rectified
/// in a future version. If the user attempted to switch locales, and
/// there was an error fetching translations for the new one, the old
/// translator will be provided here.*
WithReactor,
/// Perseus was able to successfully instantiate a reactor and translator,
/// but this error view is being rendered on the engine-side, and there is
/// no global state available.
///
/// Although global state could theoretically be provided to error pages
/// *sometimes*, the complexity and cloning involved make this extremely
/// nuanced (e.g. exported error pages can't access localized global
/// state because they don't know their locale, global state might be
/// only partially built at the time of the error, etc.). In
/// general, error views rendered on the engine-side will have this (though
/// not always).
FullNoGlobal,
/// Perseus was able to successfully instantiate everything, including a
/// translator, but then it encountered an error. You have access to all
/// the usual things you would have in a page here.
///
/// Note that this would also be given to you on the engine-side when you
/// have a translator available, but when you're still rendering to an
/// [`SsrNode`].
Full,
}
/// Where an error is being rendered. Most of the time, you'll use this for
/// determining how you want to style an error view. For instance, you probably
/// don't want giant text saying "Page not found!" if the error is actually
/// going to be rendered inside a tiny little widget.
///
/// Note that you should also always check if you have a `Popup`-style error, in
/// which case there will be no router available, so any links will be handled
/// by the browser's default behavior.
#[derive(Clone, Copy, Debug)]
pub enum ErrorPosition {
/// The error will take up the whole page.
Page,
/// The error will be confined to the widget that caused it.
Widget,
/// The error is being rendered in a little popup, and no router is
/// available.
///
/// This is usually reserved for internal errors, where something has gone
/// severely wrong.
Popup,
}
/// The information to render an error on the server-side, which is usually
/// associated with an explicit HTTP status code.
///
/// Note that these will never be generated at build-time, any problems there
/// will simply cause an error. However, errors in the build process during
/// incremental generation *will* return one of these.
///
/// This `struct` is embedded in the HTML provided to the client, allowing it to
/// be extracted and rendered.
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct ServerErrorData {
/// The HTTP status code of the error (since these errors are always
/// transmitted from server to client).
pub(crate) status: u16,
/// The actual error message. In error pages that are exported, this will be
/// simply the `reason-phrase` for the referenced status code,
/// containing no more information, since it isn't available at
/// export-time, of course.
pub(crate) msg: String,
}
// --- Default error views (development only) ---
#[cfg(debug_assertions)] // This will fail production compilation neatly
impl<G: Html> Default for ErrorViews<G> {
fn default() -> Self {
Self::unlocalized_development_default()
}
}