ResponseRepresentable

Traditionally HTTP servers take a Request and return a Response. Vapor is no different, but we can take advantage of Swift's powerful protocols to be a bit more flexible to the user facing API.

Let's start with the definition of ResponseRepresentable

public protocol ResponseRepresentable {
    func makeResponse() throws -> Response
}

By conforming to this protocol, we can more flexibly return things that conform instead of creating the response manually each time. Vapor provides some of these by default. Including (but not limited to):

String

Because string conforms to ResponseRepresentable, we can return it directly in a Vapor route handler.

drop.get("hello") { request in
    return "Hello, World!"
}

JSON

JSON can be returned directly instead of recreating a response each time.

drop.get("hello") { request in
    var json = JSON()
    try json.set("hello", "world")
    try json.set("some-numbers", [1, 2, 3])
    return json
}

Response

Of course, we can also return Responses for anything not covered:

drop.get("hello") { request in
    return Response(
        status: .ok, 
        headers: ["Content-Type": "text/plain"], 
        body: "Hello, World!"
    )
}

Conforming

All we need to do to return our own objects is conform them to ResponseRepresentable. Let's look at an example type, a simple blog post model:

import Foundation

struct BlogPost {
  let id: String
  let content: String
  let createdAt: NSDate
}

And now, let's conform it to response representable.

import HTTP

extension BlogPost: ResponseRepresentable {
    func makeResponse() throws -> Response {
        var json = JSON()
        try json.set("id", id)
        try json.set("content", content)
        try json.set("created-at", createdAt.timeIntervalSince1970)
        return try json.makeResponse()
    }
}

Now that we've modeled our BlogPost, we can return it directly in route handlers.

drop.post("post") { req in
    guard let content = request.data["content"] else { 
        throw Error.missingContent 
    }
    let post = Post(content: content)
    try post.save(to: database)
    return post
}