Rest Helpers

11.05.2021 20:35

I extracted all the boilerplate to perform a REST get operation into rest-helpers:

(defun get-json (url)
    (let ((json))
        (ignore-errors   
            (multiple-value-bind 
                (data status) 
                (drakma:http-request url)
                (if (= 200 status) 
                    (let* ((str (flexi-streams:octets-to-string data)))
                    (setq json (json:decode-json-from-string str))))))
        (unless json (format t "~&Unable to fetch from ~A~%" url))    
        json))

Using both rest-helpers and json-helpers (from previous post), to get a list of astronauts in space requires much less code:

(defun get-astronauts ()
    (mapcar #'format-astronaut 
        (get-json-value `(:people) 
        (get-json "http://api.open-notify.org/astros.json"))))

It is just as easy to get the weather in Singapore (the sunny island I come from):

(defvar *weather-endpoint* "http://api.openweathermap.org/data/2.5/weather")

(defvar *api-key* (uiop:getenv "OPEN_WEATHER_MAP_API_KEY"))

(defun make-request-url (query)
    (concatenate 'string *weather-endpoint* "?q=" query "&APPID=" *api-key*))

(defun get-weather (query)
    (get-json (make-request-url query)))

(print (get-weather "Singapore"))

Two more things I learnt this week:

How to read environment variables using (uiop:getenv ...) form.
How to enable syntax highlighting for the lisp code snippets in this post.