Clojure Rest

Clojure Rest is a library for building RESTful web services in Clojure. It provides a set of macros and functions that make it easy to create and manage HTTP endpoints.

Installation

To use Clojure Rest in your project, add the following dependency to your project.clj file:

[compojure "1.6.2"]

Getting Started

Clojure Rest is built on top of Compojure, a popular Clojure web framework. To create a new RESTful endpoint, define a new route in your Compojure handler:

(defroutes app-routes
  (GET "/api/hello" []
    {:status 200
     :body "Hello, world!"}))

In this example, we define a route that responds to GET requests to /api/hello with a simple "Hello, world!" message. We specify the response status and body using a map, which is a typical pattern in Clojure Rest.

Parameters

Clojure Rest makes it easy to extract parameters from HTTP requests, including path parameters, query parameters, and request bodies. To extract a path parameter, use the path-param function:

(GET "/api/user/:id" [id]
  (let [user (db/fetch-user id)]
    {:status 200
     :body user}))

In this example, we extract the id parameter from the request URL, fetch a user from the database using that ID, and return the user as JSON.

To extract query parameters, use the query-param function:

(GET "/api/users" []
  (let [name (query-param "name")
        users (db/find-users-by-name name)]
    {:status 200
     :body users}))

In this example, we extract the name query parameter from the request URL, find all users with that name in the database, and return them as JSON.

Clojure Rest also provides functions for parsing and validating request bodies, including JSON and EDN.

Middleware

Clojure Rest works seamlessly with Compojure middleware, including authentication and authorization middleware. Middleware can be applied to individual routes or to an entire Compojure handler:

(def app
  (-> app-routes
      (wrap-authentication)
      (wrap-authorization)))

In this example, we apply two middleware functions to our Compojure handler: wrap-authentication and wrap-authorization. These functions are responsible for authenticating and authorizing requests, respectively.

Conclusion

Clojure Rest is a powerful library for building RESTful web services in Clojure. With its rich set of features and seamless integration with Compojure, it makes it easy to create scalable, maintainable APIs.