tvl-depot/src/handlers.rs
Vincent Ambo 0ec214423e fix(handlers): Fix chained error handling in actors
This took me some time to figure out so it's useful to document in the
commit message.

When chaining messages from actors, the result type of a message (i.e.
the actual `<M as Message>::Result`) is sometimes itself a
`Result<T, E>`.

In many cases this leads to a situation where the return type of a
message sending process is something like (simplified):

    Future<Item=Result<Foo, ConverseError>, Error=actix::MailboxError>

Due to the implementation of
`From<actix::MailboxError> for ConverseError` it is possible to use
`.from_err()` on these futures to convert the future's `Error` to
`ConverseError`.

The type `Result` apparently implements `IntoFuture`, which means that
due to some trait magic that's been applied somewhere in the futures
API a call to `flatten()` can "lift" the contained error if the error
types match and give us a "simple"

    Future<Item=Foo, Error=ConverseError>

From that point on chaining becomes easy.
2018-04-12 00:04:37 +02:00

179 lines
5.6 KiB
Rust

//! This module contains the implementation of converse's actix-web
//! HTTP handlers.
//!
//! Most handlers have an associated rendering function using one of
//! the tera templates stored in the `/templates` directory in the
//! project root.
use actix::prelude::*;
use actix_web;
use actix_web::*;
use actix_web::middleware::{Started, Middleware, RequestSession};
use db::*;
use errors::ConverseError;
use futures::Future;
use models::*;
use oidc::*;
use render::*;
type ConverseResponse = Box<Future<Item=HttpResponse, Error=ConverseError>>;
const HTML: &'static str = "text/html";
/// Represents the state carried by the web server actors.
pub struct AppState {
/// Address of the database actor
pub db: Addr<Syn, DbExecutor>,
/// Address of the OIDC actor
pub oidc: Addr<Syn, OidcExecutor>,
/// Address of the rendering actor
pub renderer: Addr<Syn, Renderer>,
}
pub fn forum_index(state: State<AppState>) -> ConverseResponse {
state.db.send(ListThreads)
.flatten()
.and_then(move |res| state.renderer.send(IndexPage {
threads: res
}).from_err())
.flatten()
.map(|res| HttpResponse::Ok().content_type(HTML).body(res))
.responder()
}
/// This handler retrieves and displays a single forum thread.
pub fn forum_thread(state: State<AppState>, thread_id: Path<i32>) -> ConverseResponse {
let id = thread_id.into_inner();
state.db.send(GetThread(id))
.flatten()
.and_then(move |res| state.renderer.send(ThreadPage {
thread: res.0,
posts: res.1,
}).from_err())
.flatten()
.map(|res| HttpResponse::Ok().content_type(HTML).body(res))
.responder()
}
/// This handler presents the user with the "New Thread" form.
pub fn new_thread(state: State<AppState>) -> ConverseResponse {
state.renderer.send(NewThreadPage).flatten()
.map(|res| HttpResponse::Ok().content_type(HTML).body(res))
.responder()
}
#[derive(Deserialize)]
pub struct NewThreadForm {
pub title: String,
pub body: String,
}
/// This handler receives a "New thread"-form and redirects the user
/// to the new thread after creation.
pub fn submit_thread(state: State<AppState>,
input: Form<NewThreadForm>,
mut req: HttpRequest<AppState>) -> ConverseResponse {
// Author is "unwrapped" because the RequireLogin middleware
// guarantees it to be present.
let author: Author = req.session().get(AUTHOR).unwrap().unwrap();
let new_thread = NewThread {
title: input.0.title,
body: input.0.body,
author_name: author.name,
author_email: author.email,
};
state.db.send(CreateThread(new_thread))
.from_err()
.and_then(move |res| {
let thread = res?;
info!("Created new thread \"{}\" with ID {}", thread.title, thread.id);
Ok(HttpResponse::SeeOther()
.header("Location", format!("/thread/{}", thread.id))
.finish())
})
.responder()
}
#[derive(Deserialize)]
pub struct NewPostForm {
pub thread_id: i32,
pub body: String,
}
/// This handler receives a "Reply"-form and redirects the user to the
/// new post after creation.
pub fn reply_thread(state: State<AppState>,
input: Form<NewPostForm>,
mut req: HttpRequest<AppState>) -> ConverseResponse {
// Author is "unwrapped" because the RequireLogin middleware
// guarantees it to be present.
let author: Author = req.session().get(AUTHOR).unwrap().unwrap();
let new_post = NewPost {
thread_id: input.thread_id,
body: input.0.body,
author_name: author.name,
author_email: author.email,
};
state.db.send(CreatePost(new_post))
.from_err()
.and_then(move |res| {
let post = res?;
info!("Posted reply {} to thread {}", post.id, post.thread_id);
Ok(HttpResponse::SeeOther()
.header("Location", format!("/thread/{}#post-{}", post.thread_id, post.id))
.finish())
})
.responder()
}
/// This handler initiates an OIDC login.
pub fn login(state: State<AppState>) -> ConverseResponse {
state.oidc.send(GetLoginUrl)
.from_err()
.and_then(|url| Ok(HttpResponse::TemporaryRedirect()
.header("Location", url)
.finish()))
.responder()
}
const AUTHOR: &'static str = "author";
pub fn callback(state: State<AppState>,
data: Form<CodeResponse>,
mut req: HttpRequest<AppState>) -> ConverseResponse {
state.oidc.send(RetrieveToken(data.0))
.from_err()
.and_then(move |result| {
let author = result?;
info!("Setting cookie for {} after callback", author.name);
req.session().set(AUTHOR, author)?;
Ok(HttpResponse::SeeOther()
.header("Location", "/")
.finish())})
.responder()
}
/// Middleware used to enforce logins unceremonially.
pub struct RequireLogin;
impl <S> Middleware<S> for RequireLogin {
fn start(&self, req: &mut HttpRequest<S>) -> actix_web::Result<Started> {
let has_author = req.session().get::<Author>(AUTHOR)?.is_some();
let is_oidc_req = req.path().starts_with("/oidc");
if !is_oidc_req && !has_author {
Ok(Started::Response(
HttpResponse::SeeOther()
.header("Location", "/oidc/login")
.finish()
))
} else {
Ok(Started::Done)
}
}
}