**Routing**
================

WebApi_ supports the following HTTP verbs
**GET**, **POST**, **PUT**, **DELETE**, **PATCH**, **HEAD**

You can also use any :wahackage:`Custom <WebApi-Method.html#t:CUSTOM>` method as per your needs.

In WebApi_ we need to first write all the routes as types and then declare the valid HTTP verbs for each route type.

Routes as types
---------------
Each route is declared as a type. For demo purposes let's consider a API service that would allow you to create and get users. We need two URIs. One to create a user and another one to get the user by her ID.

:code:`/user` **URI to create a user**
::

  type User = Static "user"


:code:`/user/9` **URI to get a user**
::

  type UserId = "user" :/ Int


* Note that :code:`/user` is declared as :code:`Static "user"` to wrap **user** in :code:`Static` to make all the types of the same **kind** **(*)**

As you could see in the above examples, routes are defined as types. The next step is to write a :doc:`WebApi <WebApi-Contract.html#t:WebApi>`  instance for the route types along with the HTTP verbs they support.

::

  instance WebApi MyApiService where
    -- Route <Method>  <Route Name>
     type Apis MyApiService = '[ Route '[POST]             User
                               , Route '[GET, PUT, DELETE] UserId
                               ]


In the above code snippet, we are declaring that our route type

*  :code:`User` ie (:code:`/user`) accepts :code:`POST`
*  :code:`UserId` accepts :code:`GET`, :code:`PUT`, :code:`DELETE`.

   - Let's say the user Id is 9, then :code:`GET /user/9` could be used to get the user, :code:`PUT /user/9` to edit the user and :code:`DELETE user/9` to delete the user.

More examples
-------------

:code:`/post/tech/why-i-like-web-api`
::

  type Post = "post" :/ Text :/ Text

:code:`/post/tech/why-i-like-web-api/edit`
::


  type EditPost = "post" :/ Text :/ Text :/ "edit"

:code:`/why-i-like-web-api/comments`
::


  type Comments = Text :/ "comments"

.. note:: Please note that when two route format overlaps, for example :code:`user/posts` and :code:`user/brian` WebApi's routing system would take the first route that is declared first in the :code:`WebApi` instance.

.. _WebApi : https://hackage.haskell.org/package/webapi