Mini web: Simple function dispatcher for web applications.
On web applications, we normally have a single entry point which has to handle many different requests to different URIs, with different GET/POST/etc parameters
mweb - which was inspired by haxe.web.Dispatch class - presents a way to deal with this problem in
a declarative and composable manner. It uses the concept of Routes to define which function should
be executed for each route.
The routes are created declaratively - either by creating a class that extends mweb.Route, or by
using an anonymous object.
/**
This is an example route
It has only one route location:
/ - shows an instructions page
/hello/{name} - shows a "Hello, {name} message"
**/
class HelloRoute extends mweb.Route<String>
{
public static function main()
{
var request = new mweb.http.webstd.Request(); // works for neko.Web and php.Web
var d = mweb.Dispatcher.createWithRequest(request);
var ret = d.dispatch(new HelloRoute());
Sys.print(ret);
}
public function anyHello(name:String):String
{
return '<h1>Hello, $name!</h1>';
}
public function any():String
{
return '<p>Welcome to the first example of mweb!</p>' +
'<p>In order to test it, change your browser location to point to <code>/hello/yourname</code> <a href="https://github.com/waneck/mweb/blob/master/hello/user">like this</a></p>';
}
/**
this function will not be route because it's a
private function
**/
private function willNotBeRoute():Void
{
}
/**
this function will not be route because it has the
@:skip metadata
**/
@:skip public function willNotBeRouteEither():Int
{
return 1;
}
}The first thing to note here is that a mweb.Route takes a type parameter. That type parameter represents what
type each of its routes should return. Return-type covariance is taken into account.
About naming, we have some special prefixes that filter the accepted function methods allowed:
get,post,delete,patch,put. Each of these prefixes represents an HTTP verb.
If you want that the function take any verb, you can use any
So by these definitions, we have two routes at HelloRoute:
<root> : takes any verb: shows an instructions page<root>/hello/{name} : takes any verb, and expects a String argument in the addressThere may be more than one route address argument. If we change the anyHello function to match the following:
public function anyHello(name:String, ?age:Int):String
{
return '<h1>Hello, $name!' + (age == null ? '' : ' You are $age years old') + '</h1>';
}The route <root>/hello/{name} will still work the same, but a <root>/hello/{name}/{age} address route is
possible. The ? marker on age denotes the argument as optional
Differently from the first (name) argument, the age argument is an Int. This will go through a type check when dispatching the route -
and any address that isn't an Integer will be rejected by the dispatcher. So for example <root>/hello/myname/not_an_int will fail with the
mweb.Errors.DispatcherErrorType.InvalidArgumentType error
We've seen how to use mweb to use address arguments. However address arguments do not play well with form values, which get sent through
GET/POST parameters. In order to use them, a special argument named args can be included as the last argument of a route.
The args argument must always be an anonymous type definition:
/**
This is an example route
It has two route locations:
/ - shows a form for the user to enter his name
/hello - says hello to the user who posted his name
**/
class HelloRoute extends mweb.Route<String>
{
public static function main()
{
var request = new mweb.http.webstd.Request(); // works for neko.Web and php.Web
var d = mweb.Dispatcher.createWithRequest(request);
var ret = d.dispatch(new HelloRoute());
Sys.print(ret);
}
public function any():String
{
return
'<h1>Please enter your name</h1>' +
'<form action="/hello" method="POST">' +
'<input type="text" name="theName" />' +
'<input type="submit" />' +
'</form>';
}
public function postHello(args:{ theName:String }):String
{
return '<h1>Hello, ${args.theName}</h1>';
}
}So by these definitions, we have two routes at HelloRoute:
<root> : takes any verbs: shows a form asking the user to enter his name<root>/hello : takes only the POST verb, and there must be on the body of the message a String parameter called theNameWe can further modify this example so we can have only the <root> route:
/**
This is an example route
It has two route locations:
/ - shows a form for the user to enter his name
/ - [POST method] says hello to the user who posted his name
**/
class HelloRoute extends mweb.Route<String>
{
public static function main()
{
var request = new mweb.http.webstd.Request(); // works for neko.Web and php.Web
var d = mweb.Dispatcher.createWithRequest(request);
var ret = d.dispatch(new HelloRoute());
Sys.print(ret);
}
public function any():String
{
return
'<h1>Please enter your name</h1>' +
'<form action="/" method="POST">' +
'<input type="text" name="theName" />' +
'<input type="submit" />' +
'</form>';
}
public function post(args:{ theName:String }):String
{
return '<h1>Hello, ${args.theName}</h1>';
}
}The post function will take priority over any when a POST method is used.
Like with address arguments, args can be optional - so if no argument is present, the function will still be called.
Knowing that, we can further modify this example:
/**
This is the 2nd sample route.
It has one route location:
/ - shows either a form for the user to enter his name or a greeting message
**/
class HelloRoute extends mweb.Route<String>
{
public static function main()
{
var request = new mweb.http.webstd.Request(); // works for neko.Web and php.Web
var d = mweb.Dispatcher.createWithRequest(request);
var ret = d.dispatch(new HelloRoute());
Sys.print(ret);
}
public function any(?args:{ theName:String }):String
{
if (args != null)
return '<h1>Hello, ${args.theName}</h1>';
else
return
'<h1>Please enter your name</h1>' +
'<form action="/" method="POST">' +
'<input type="text" name="theName" />' +
'<input type="submit" />' +
'</form>';
}
}While the example above is possible - it is recommended to filter only the required method when using args
Also note that args can also have its type inferred from usage:
public function post(args):String
{
return '<h1>Hello, ${args.theName}</h1>';
}Apart from the basic types such as String, Int, Float, Bool, one can use more complex types.
Any non-basic type can be used provided that a decoder function is registered. Since our input is a JSON-like object, a decoder function may have one of the following signature:
typedef StringDecoder<T> = String->Null<T>;
typedef IntDecoder<T> = Int->Null<T>;
typedef FloatDecoder<T> = Float->Null<T>;
typedef ArrayDecoder<T> = Array<Dynamic>->Null<T>;
typedef DynamicDecoder<T> = Dynamic->Null<T>;More than one decoder functions may be registered - for different input types; The decoder function itself may throw errors,
and if the input data is invalid, it should return null. If either null is returned or an error is thrown, the decoding will be considered invalid,
and an error of type mweb.Errors.DecoderError will be thrown.
Any class or abstract type which has a fromString, fromInt, fromFloat or fromDynamic static function that takes their respective type and returns the type itself can be used directly;
So for example Date from the standard library - which has a fromString function which is compatible -
can be used directly without registering decoder. Abstract @:from functions are also analyzed - if there is any @:from which takes a String as an argument
Otherwise, you can register a decoder function by calling mweb.Decoder.add. The type which it is decoding to is inferred from the function's signature:
mweb.Dispatcher.addDecoder(function(string:String):Null<SomeType> return decodeSomeType(string)); //This will add a decoder from String to `SomeType`
mweb.Dispatcher.addDecoder(function(int:Int):Null<SomeType> return decodeSomeType(int)); //This will add a decoder from Int to `SomeType`Please note that mweb.Decoder.add must be called before any dispatch is called.
Both Anonymous and Array types have special handling.
On address arguments, Anonymous types are not allowed since they make little sense in this context.
Array types are allowed provided that they are the last address argument. In this cases, they function like Rest methods -
in which all extra address parts are added to it:
// the following route:
function anyTest(i:Int,rest:Array<String>) {}
// can respond to an address part like /test/1/a/b/c/d/e
// but the following route will error:
function anyTest(i:Int,rest:Array<String>,shouldntExist:Int) {}args argumentsThe args arguments can accept both Array and