Create An Atom Feed In Rust

Introduction

This is what I'm doing to make an Atom feed for my site. More notes below the code.

Code

//! ```cargo
//! [dependencies]
//! atom_syndication = "0.12.2"
//! chrono = { version = "0.4.26", features = ["std"] }
//! uuid = { version = "1.6.1", features = ["v5"] }
//! ```

use atom_syndication::*;
use chrono::prelude::*;
use std::collections::BTreeMap;
use std::fs;
use uuid::Uuid;


fn main() {

  let feed_constant_uuid4 = Uuid::try_parse(
    "b71fc261-fc1a-4220-b43f-2be4b216c0b2"
  ).unwrap();

  let generation_date = chrono::offset::Utc::now().fixed_offset();

  let author = Person {
    name: "Alan W. Smith".to_string(), 
    email: None,
    uri: Some("https://www.example.com/".to_string())
  };

  let entry_uuid5 = format!("urn:uuid:{}", Uuid::new_v5(
    &feed_constant_uuid4, b"unque_file_id_alfa")
      .as_hyphenated()
      .to_string()
  );

  let entry_title = Text {
    value: "This Is A Title".to_string(),
    base: None, 
    lang: None,
    r#type: TextType::Text
  };

  let tz_hour_offset = 5; 
  let tz = FixedOffset::west_opt(tz_hour_offset * 60 * 60).unwrap();
  let updated_date = NaiveDateTime::parse_from_str("2023-12-17 10:33:55", "%Y-%m-%d %H:%M:%S")
    .unwrap()
    .and_local_timezone(tz)
    .unwrap();

  let entry_content = Some(
    Content {
      base: None, 
      lang: None, 
      value: Some("<p>Hello, world</p>".to_string()),
      src: Some("https://www.example.com/some_path.html".to_string()),
      content_type: Some("html".to_string()),
    }
  );

  let entry = Entry {
      id: entry_uuid5,
      title: entry_title,
      authors: vec![author.clone()],
      categories: vec![],
      content: entry_content,
      summary: None, 
      source: None,
      rights: None, 
      published: None, 
      links: vec![],
      contributors: vec![],
      updated: updated_date,
      extensions: BTreeMap::new() 
  };

  let entries = vec![entry];

  let feed_id = format!(
    "urn:uuid:{}",
    feed_constant_uuid4.as_hyphenated()
  );

  let feed_link = Link{
    href: "https://www.example.com/atom.xml".to_string(),
    rel: "self".to_string(),
    hreflang: None, 
    length: None, 
    mime_type: None,
    title: None
  };

  let feed = Feed {
    title: "My Example Feed".into(),
    id: feed_id,
    updated: generation_date,
    authors: vec![author],
    links: vec![feed_link],
    entries,
    ..Default::default()
  };

  let config = WriteConfig {
    write_document_declaration: true,
    indent_size: Some(2),
  };

  let file = fs::OpenOptions::new()
    .create(true)
    .truncate(true)
    .write(true)
    .open("/Users/alan/Desktop/atom-test.xml").unwrap();

  // output the file
  feed.write_with_config(&file, config).unwrap();

  // print it for demo
  println!("{}", feed.to_string());
}

Results

<?xml version="1.0"?>
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>My Example Feed</title>
  <id>urn:uuid:b71fc261-fc1a-4220-b43f-2be4b216c0b2</id>
  <updated>2024-01-02T23:29:27.999342+00:00</updated>
  <author>
    <name>Alan W. Smith</name>
    <uri>https://www.example.com/</uri>
  </author>
  <link href="https://www.example.com/atom.xml" rel="self"/>
  <entry>
    <title>This Is A Title</title>
    <id>urn:uuid:b1507332-d46c-5bcf-929a-f89c59e01bac</id>
    <updated>2023-12-17T10:33:55+05:00</updated>
    <author>
      <name>Alan W. Smith</name>
      <uri>https://www.example.com/</uri>
    </author>
    <content type="html" src="https://www.example.com/some_path.html">&lt;p&gt;Hello, world&lt;/p&gt;</content>
  </entry>
</feed>

Notes

This is for an Atom feed. A similar crate exists for RSS (linked below)
I went with Atom based off
The UUIDs work by creating a UUID4 that stays the same every time the feed is generated and then a UUID5 for each file based off an ID that's attached to the file
The UUID5 is a combination of the main feeds UUID4 + the unique ID for the file. Given those two inputs the output is always the same. That lets the individual entry IDs stay the same even if their content changes.
The `updated_date`` is a `atom_syndication::FixedDateTime`` which is an alias of `chrono::DateTime<::chrono::FixedOffset<`` from the chrono crate
My content file dates don't have a timezone (e.g. `2023-07-15 18:02:07``). The `tz_hour_offset`` is my offset from GMT which I use to calculate the data to get to the `DateTime`` that's needed
The rest of the date code converts to the necessary object format that then outputs with a timezone like: `2023-07-15T18:02:07+05:00`` in the feed
There's a bunch of things set to `None`` across the code. The docs (linked below) list all those details
The content comes out as HTML escaped characters. (e.g. `
I put two outputs in the example. The first one outputs to a file with a config attached that pretty prints the contents. The second one outputs a string. I haven't figure out a way to pretty print that though
I'm not sure what the 'rel' should be. I tried "canonical" at first, but it didn't work with RSS Parrot. I've now changed it to "self" which is what I've now seen on other feeds. We'll see what happens

Create An Atom Feed In Rust

Introduction

Code

Results

Notes

References