Let's start by defining a few endpoints for our service. We'll be implementing the logic for each of these endpoints later; for now, we'll ensure the following routes are present in the API and return 200 OK responses.

User Routes

For the purpose of these routes, you can assume the user's handle looks like @userName. Don't worry about encoding/decoding the @ symbol in the URL.

  • POST /api/users/:handle - Creates a new user
  • GET /api/users/:handle/posts - Returns all posts of a user by their handle, ordered by time

Post Routes

  • POST /api/posts - Creates a new post
  • GET /api/posts/:id - Returns a post by its ID

Follower Routes

  • POST /api/follow/:handle - Follows a user by their handle
  • GET /api/following - Returns all users you're following
  • DELETE /api/follow/:handle - Unfollows a user by their handle

Feed Routes

  • GET /api/feed/:handle - Returns all posts of the people the user is following, ordered by time.

Routes library basics

We'll be using the Routes library to define our endpoints.

There are two top-level functions for defining a service endpoint, Route.noCapture and Route.route. Use Route.noCapture if your route does not capture any path parameters or Route.route, if it extracts a path segment for use as a variable.

The Routes library provides a few functions, such as ok.text or headers.add, that help build HTTP responses. Combining the two, route definition and HTTP response construction, will create a complete endpoint:

api.createPost : '{Route} ()
api.createPost = do
  use Parser / s
  Route.noCapture POST (s "api" / s "posts")
  ok.text "ok"

api.getPostById : '{Route} ()
api.getPostById =
  do
    use Parser / s
    postId =
      PostId
        (Route.route
          GET (s "api" / s "posts" / Parser.text))
    ok.text "ok"

We recommend defining one function per route, and then combining them all together with Route.<|> in a final call to Route.run. Route.run produces a function that takes an HttpRequest and returns an HttpResponse, which is the expected type for deploying an HTTP service.

Route.run : '{g, Route, Exception} ()
                         -> HttpRequest
                         ->{g, Exception} HttpResponse

📚 Instructions

Define the remaining endpoints by having them return a 200 OK response for each route. The response body does not matter for now.

We've provided two route stubs to use as a reference for this part of the exercise:

  • api.getPostById - "GET /api/posts/:id"
  • api.createPost - "POST /api/posts"

Deploy all your routes as an HTTP service inside the provided ex3_microblog.deploy function. It should return the URI where the service is deployed.

cloud-start/main> edit ex3_microblog.deploy

When you've implemented all the routes, update your codebase and run your solution.

cloud-start/main> run submit.ex3_microblog.pt1