Generating XML With Bootleg

Adding a little RSS goodness to your bootleg site

Crispin Wellington
Feb 2, 2020 · 3 min read
unsplash-logoEdward Virvel

Outputting XML with Bootleg

The latest release of bootleg (0.1.7) contains some new XML output functionality. I added this to bootleg to facilitate the generation of an RSS news feed form the epiccastle blog page that you are reading right now. Here is how I generate this RSS.


In this blog I have post metadata stored in some short yaml files. I can gather all the relevant filenames in with the glob function:

(for [filename (glob "*/vars.yml")]

And then I can read these vars in with the yaml function:

(let [vars (yaml filename)]

I build all these yaml structures into a single hash map keyed by the post number.

(let [posts
      (->> (for [filename (glob "*/vars.yml")]
             (let [post-num (-> filename
                                (string/split #"/")
                   vars (yaml filename)]
               [post-num vars]))
           (into {}))]

Generating the RSS

I can now use this datastructure to generate an rss xml file. I do this by passing some hiccup to (convert-to hiccup-data :xml)

(spit "feed.xml"
    (-> [:rss {:version "2.0"}
            [:title "Epiccastle Blog"]
            [:description " Updates"]
            [:link ""]
            [:lastBuildDate now-string]
            [:pubDate now-string]
            [:ttl "1440"]
            (for [[n {:keys [snake-title
                      :as post-data}] (reverse (sort posts))]
               [:title title]
               [:description (-> post-data
               [:link (str "" snake-title)]
               [:gid snake-title]
               [:pubDate rss-date]])]]
          (convert-to :xml)))

Other helpful functions

I needed to escape the html markup to embed it in the xml description tag with this function:

(defn escape-html
  "Change special characters into HTML character entities."
  (-> text
      (string/replace "&" "&")
      (string/replace "<" "&lt;")
      (string/replace ">" "&gt;")
      (string/replace "\"" "&quot;")))

And my now-string variable I generate with the following simple code at the top of my file:

(import [java.time OffsetDateTime]
        [java.time.format DateTimeFormatter])

(defn string->datetime [s]
  (OffsetDateTime/parse s DateTimeFormatter/RFC_1123_DATE_TIME))

(defn datetime->string [dt]
  (.format dt DateTimeFormatter/RFC_1123_DATE_TIME))

(def now (OffsetDateTime/now))
(def now-string (datetime->string now))

You can see the actual source for this process here.

About Crispin Wellington

Crispin Wellington is a Software Developer and System Operations expert with over 25 years of professional experience. As well as being the founder of Epic Castle he is the founder and developer of He is based in Perth, Australia and is a husband and father. As Epic Castle's principal consultant he is available to assist you in solving your software, operations and service problems.