RSS Rocket Handlebar Example (Sort of...)

rss.hbs

<?xml version="1.0"?>
<rss version="2.0">
    <channel>
        <title>{{page_title}}</title>
        <link>{{page_link}}</link>
        <description>{{page_desc}}</description>
        <language>en-us</language>
        <pubDate>{{page_date}}</pubDate>
        <generator>Custom Web Server Written in Rust (RIIR)</generator>
        <webMaster>[email protected]</webMaster>
        {{#each articles}}<item>
            <title>{{title}}</title>
            <link>{{link}}</link>
            <description>{{description}}</description>
            <pubDate>{{date}}</pubDate>
            <guid>{{link}}</guid>
        </item>{{/each}}
    </channel>
</rss>

rss.rs

use accept_encoding::AcceptEncoding;
use cacher::{Page, PageCache, CachedContent};
use chrono::{DateTime, UTC};
use database::DBConnection;
use std::error::Error;
use posts::index::get_summary;
use rocket::State;
use rocket_contrib::Template;

macro_rules! request_content {
    ($cache:ident, $url:ident, $encoding:ident, $closure:expr) => {
        match $cache.request_content($url.clone(), $encoding) {
            Ok(content) => Ok(content),
            Err(action) => $cache.update_cache($url, action, $encoding, $closure)
        }
    }
}

#[derive(Serialize)]
pub struct RssArticle {
    title: String,
    link: String,
    description: String,
    date: String,
}

#[derive(Serialize)]
struct RssFeed {
    page_title: String,
    page_link: String,
    page_desc: String,
    page_date: String,
    articles: Vec<RssArticle>
}

impl RssFeed {
    pub fn new <I: Iterator<Item = RssArticle>> (
        title: String,
        link: String,
        description: String,
        articles: I
    ) -> RssFeed {
        RssFeed {
            page_title: title,
            page_link: link,
            page_desc: description,
            page_date: UTC::now().to_rfc2822(),
            articles: articles.collect::<Vec<RssArticle>>()
        }
    }
}

const RSS_INDEX: &'static str = r#"SELECT
    title, uuid, content, time_published
FROM posts ORDER BY time_published DESC LIMIT $1 OFFSET $2"#;

#[get("/rss")]
pub fn main_rss (
    cache: State<PageCache>,
    db: DBConnection,
    encoding: AcceptEncoding
) -> Result<CachedContent, String> {
    let url = String::from("/rss");

    // Request for a cached compressed copy, and if it doesn't exist, or the cached copy is too
    // old, generate a new copy.
    request_content!(cache, url, encoding, || {
        // Perform a DB query to get the latest N elements.
        let query = db.get().query(RSS_INDEX, &[&15i64, &0i64])
            .map_err(|why| why.description().to_owned())?;

        // Generate the context elements needed for the RSS handlebar template.
        let feed = RssFeed::new (
            // The title of the supplied contents.
            "Michael Murphy's Personal Blog".into(),
            // The URL where the contents are stored.
            "https://mmstick.tk/".into(),
            // A description of the page's contents.
            "The latest posts on Michael's personal blog.".into(),
            // Creates an iterator that generates `RssArticle`s from the database queries.
            query.iter().map(|article| RssArticle {
                title: article.get(0),
                link: {
                    let link: String = article.get(1);
                    ["https://mmstick.tk/post/", &link].concat()
                },
                description: {
                    let description: String = article.get(2);
                    match get_summary(&description) {
                        Ok(summary) => summary.to_owned(),
                        Err(why) => why.to_owned()
                    }
                },
                date: {
                    let date: DateTime<UTC> = article.get(3);
                    date.to_rfc2822()
                }
            })
        );

        // Generate the RSS XML from the template and convert it into a compressed page.
        Ok(Page::new(Template::render("rss", &feed), encoding).into())
    })
}