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diff --git a/compojure.html.markdown b/compojure.html.markdown new file mode 100644 index 00000000..56f43cb7 --- /dev/null +++ b/compojure.html.markdown @@ -0,0 +1,225 @@ +--- +category: tool +tool: compojure +contributors: + - ["Adam Bard", "http://adambard.com/"] +filename: learncompojure.clj +--- + +## Getting Started with Compojure + +Compojure is a DSL for *quickly* creating *performant* web applications +in Clojure with minimal effort: + +```clojure +(ns myapp.core + (:require [compojure.core :refer :all] + [org.httpkit.server :refer [run-server]])) ; httpkit is a server + +(defroutes myapp + (GET "/" [] "Hello World")) + +(defn -main [] + (run-server myapp {:port 5000})) +``` + +Create a project with [Leiningen](http://leiningen.org/): + +``` +lein new myapp +``` + +Add your dependencies: + +``` +[compojure "1.1.8"] +[http-kit "2.1.16"] +``` + +And run: + +``` +lein run -m myapp.core +``` + +View at: <http://localhost:5000/> + +Compojure apps will run on any ring-compatible server, but we recommend +[http-kit](http://http-kit.org/) for its performance and +[massive concurrency](http://http-kit.org/600k-concurrent-connection-http-kit.html). + +### Routes + +In compojure, each route is an HTTP method paired with a URL-matching pattern, +an argument list, and a body. + +```clojure +(defroutes myapp + (GET "/" [] "Show something") + (POST "/" [] "Create something") + (PUT "/" [] "Replace something") + (PATCH "/" [] "Modify Something") + (DELETE "/" [] "Annihilate something") + (OPTIONS "/" [] "Appease something") + (HEAD "/" [] "Preview something")) +``` + +Compojure route definitions are just functions which +[accept request maps and return response maps](https://github.com/mmcgrana/ring/blob/master/SPEC): + +```clojure +(myapp {:uri "/" :request-method :post}) +; => {:status 200 +; :headers {"Content-Type" "text/html; charset=utf-8} +; :body "Create Something"} +``` + +The body may be a function, which must accept the request as a parameter: + +```clojure +(defroutes myapp + (GET "/" [] (fn [req] "Do something with req"))) +``` + +Route patterns may include named parameters, + +```clojure +(defroutes myapp + (GET "/hello/:name" [name] (str "Hello " name))) +``` + +You can match entire paths with * + +```clojure +(defroutes myapp + (GET "/file/*.*" [*] (str *))) +``` + +Handlers may utilize query parameters: + +```clojure +(defroutes myapp + (GET "/posts" [] + (fn [req] + (let [title (get (:params req) "title") + author (get (:params req) "title")] + " Do something with title and author")))) +``` + +Or, for POST and PUT requests, form parameters + +```clojure +(defroutes myapp + (POST "/posts" [] + (fn [req] + (let [title (get (:params req) "title") + author (get (:params req) "title")] + "Do something with title and author")))) +``` + + +### Return values + +The return value of a route block determines at least the response body +passed on to the HTTP client, or at least the next middleware in the +ring stack. Most commonly, this is a string, as in the above examples. +But, you may also return a [response body](https://github.com/mmcgrana/ring/blob/master/SPEC): + +```clojure +(defroutes myapp + (GET "/" [] + {:status 200 :body "Hello World"}) + (GET "/is-403" [] + {:status 403 :body ""}) + (GET "/is-json" [] + {:status 200 :headers {"Content-Type" "application/json"} :body "{}"})) +``` + +### Static Files + +To serve up static files, use `compojure.route.resources`. +Resources will be served from your project's `resources/` folder. + +```clojure +(require '[compojure.route :as route]) + +(defroutes myapp + (GET "/") + (route/resources "/")) ; Serve static resources at the root path + +(myapp {:uri "/js/script.js" :request-method :get}) +; => Contents of resources/public/js/script.js +``` + +### Views / Templates + +To use templating with Compojure, you'll need a template library. Here are a few: + +#### [Stencil](https://github.com/davidsantiago/stencil) + +[Stencil](https://github.com/davidsantiago/stencil) is a [Mustache](http://mustache.github.com/) template library: + +```clojure +(require '[stencil.core :refer [render-string]]) + +(defroutes myapp + (GET "/hello/:name" [name] + (render-string "Hello {{name}}" {:name name}))) +``` + +You can easily read in templates from your resources directory. Here's a helper function + +```clojure +(require 'clojure.java.io) + +(defn read-template [filename] + (slurp (clojure.java.io/resource filename))) + +(defroutes myapp + (GET "/hello/:name" [name] + (render-string (read-template "templates/hello.html") {:name name}))) +``` + +#### [Selmer](https://github.com/yogthos/Selmer) + +[Selmer](https://github.com/yogthos/Selmer) is a Django and Jinja2-inspired templating language: + +```clojure +(require '[selmer.parser :refer [render-file]]) + +(defroutes myapp + (GET "/hello/:name" [name] + (render-file "templates/hello.html" {:name name}))) +``` + +#### [Hiccup](https://github.com/weavejester/hiccup) + +[Hiccup](https://github.com/weavejester/hiccup) is a library for representing HTML as Clojure code + +```clojure +(require '[hiccup.core :as hiccup]) + +(defroutes myapp + (GET "/hello/:name" [name] + (hiccup/html + [:html + [:body + [:h1 {:class "title"} + (str "Hello " name)]]]))) +``` + +#### [Markdown](https://github.com/yogthos/markdown-clj) + +[Markdown-clj](https://github.com/yogthos/markdown-clj) is a Markdown implementation. + +```clojure +(require '[markdown.core :refer [md-to-html-string]]) + +(defroutes myapp + (GET "/hello/:name" [name] + (md-to-html-string "## Hello, world"))) +``` + +Further reading: + +[Clojure for the Brave and True](http://www.braveclojure.com/) |