Frank is a DSL for quickly writing web applications in Swift with type-safe path routing.
import Frank
// Handle GET requests to path /
get { request in
return "Hello World"
}
// Handle GET requests to path /users/{username}
get("users", *) { (request, username: String) in
return "Hello \(username)"
}
import PackageDescription
let package = Package(
name: "Hello",
dependencies: [
.Package(url: "https://github.com/kylef/Frank.git", majorVersion: 0, minor: 4)
]
)
Then build, and run it via:
$ swift build --configuration release
$ .build/release/Hello
[2016-01-25 07:13:21 +0000] [25678] [INFO] Listening at http://0.0.0.0:8000 (25678)
[2016-01-25 07:13:21 +0000] [25679] [INFO] Booting worker process with pid: 25679
Check out the full example which can be deployed to Heroku.
Routes are constructed with passing your path split by slashes /
as
separate arguments to the HTTP method (e.g. get
, post
etc) functions.
For example, to match a path of /users/kyle/followers
you can use the following:
get("users", "kyle", "followers") { request in
}
You may pass path components along with wildcard (*
) to match variables in
paths. The wildcard is a placemarker to annotate where the variable path
components are in your path. Frank allows you to use any number of wildcards
in any place of the path, allowing you to match all paths.
The wildcards will map directly to parameters in the path and the variables passed into your callback. Wildcard parameters are translated to the type specified in your closure.
// /users/{username}
get("users", *) { (request, username: String) in
return "Hi \(username)"
}
// /users/{username}/followers
get("users", *, "followers") { (request, username: String) in
return "\(username) has 5 followers"
}
You may place any type that conforms to ParameterConvertible
in your callback, this allows the types to be correctly
converted to your type or user will face a 404 since the
URL will be invalid.
// /users/{userid}
get("users", *) { (request, userid: Int) in
return "Hi user with ID: \(userid)"
}
Wildcard parameters may be of any type that conforms to ParameterConvertible
,
this allows you to match against custom types providing you conform to
ParameterConvertible
.
For example, we can create a Status enum which can be Open or Closed which
conforms to ParameterConvertible
:
enum Status : ParameterConvertible {
case open
case closed
init?(parser: ParameterParser) {
switch parser.shift() ?? "" {
case "open":
self = .open
case "closed":
self = .closed
default:
return nil
}
}
}
get("issues", *) { (request, status: Status) in
return "Issues using status: \(status)"
}
Routes are matched in the order they are defined. The first route that matches the request is invoked.
get {
...
}
put {
...
}
patch {
...
}
delete {
...
}
head {
...
}
options {
...
}
The return value of route blocks takes a type that conforms to the
ResponseConvertible
protocol, which means you can make any type Response
Convertible. For example, you can return a simple string:
get {
return "Hello World"
}
Return a full response:
get {
return Response(.ok, headers: ["Custom-Header": "value"])
}
post {
return Response(.created, content: "User created")
}
You can easily use the Stencil template
language with Frank. For example, you can create a convenience function to
render templates (called stencil
):
import Stencil
import Inquiline
import PathKit
func stencil(path: String, _ context: [String: Any]? = nil) -> ResponseConvertible {
do {
let template = try Template(path: Path(path))
let body = try template.render(Context(dictionary: context))
return Response(.ok, headers: [("Content-Type", "text/html")], content: body)
} catch {
return Response(.internalServerError)
}
}
Which can easily be called from your route to render a template:
get {
return stencil("hello.html", ["user": "world"])
}
<html>
<body>
Hello {{ user }}!
</body>
</html>
Frank is design around the Nest Swift
Web Server Gateway Interface, which allows you to use any Nest-compatible web
servers. The exposed call
function is a Nest compatible application which can
be passed to a server of your choice.
import Frank
get {
return "Custom Server"
}
// Pass "call" to your HTTP server
serve(call)