h1. VK API Compatability layer for OpenVK

This directory contains VK api handlers, structures and relared exceptions. It is still a work-in-progress functionality.
**Note**: requests to api are routed through openvk.Web.Presenters.VKAPIPresenter, this dir contains only handlers.

h2. Implementing API methods

VK API methods have names like this: @example.test@. To implement a method like this you will need to create a class @Example@ in the Handlers subdirectory. This class **must** extend VKAPIHandler and be final.
Next step is to create %test% method. It **must** have a type hint that is not %void%. Everything else is fine, the return value of method will be authomatically converted to JSON and sent back to client.

h3. Parameters

Method arguments are parameters. To declare a parameter just create an argument with the same name. You should also provide correct type hints for them. Type conversion is done automatically if possible. If not possible error №1 will be returned.
If parameter is not passed by client then router will pass default value to argument. If there is no default value but argument accepts NULL then NULL will be passed. If NULL is not acceptable, default value is undefined and parameter is not passed, API will return missing parameter error to client.

h3. Returning errors

To return an error, call %fail% method like this: @$this->fail(5, "error")@ (first argument is error code and second is error message). You can also throw the exception manually: @throw new APIErrorException("error", 5)@ (class: openvk.VKAPI.Exceptions.APIErrorException).
If you throw any exception that does not inherit APIErrorException then API will return error №1 (unknown error) to client.

h3. Refering to user

To get user use @getUser@ method: @$this->getUser()@. Keep in mind it will return NULL if user is undefined (no access_token passed or it is invalid/expired or roaming authentification failed).
If you need to check whether user is defined use @userAuthorized@. This method returns true if user is present and false if not.
If your method can't work without user context call @requireUser@ and it will automatically return unauthorized error.

h3. Working with data

You can use OpenVK models for that. However, **do not** return them (either you will leak data or JSON conversion will fail). It is better to create a response object and return it. It is also a good idea to define a structure in Structures subdirectory.

Have a lot of fun ^^
