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https://github.com/iancmcc/extdirect

Python/Zope/Django implementation of an Ext.Direct router
https://github.com/iancmcc/extdirect

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Python/Zope/Django implementation of an Ext.Direct router

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README 

        
============

Introduction

============



To use this package, you must either have simplejson installed, or be using

Python 2.6 (which includes simplejson as the json package).



ExtJS 3.0 provides Ext.Direct, an extremely simple way to remote server-side

methods to the client side. extdirect provides a Python implementation

of a server-side Ext.Direct router, which can accept and parse Ext.Direct

request data, route it to the correct method, and create, encode and return the

proper data structure wrapping the results. extdirect also provides a

class that can generate the client-side JavaScript defining an Ext.Direct

provider from a router class.



For a full description of Ext.Direct's features, see:



    http://www.extjs.com/products/extjs/direct.php



Let's see how the server side works. First, we'll define a router:



    >>> from extdirect.router import DirectRouter

    >>> class TestUtils(DirectRouter):

    ...

    ...     def capitalize(self, word):

    ...         return word.upper()

    ...

    ...     def today(self):

    ...         return "Today is Wednesday."



We've defined two methods we want remoted to the client.



Although we don't have a real client in this test runner, here's how one would

generate the code that needs to be given to the client defining the provider.

Ignoring actual implementation, which would depend on the framework being used,

let's say we'll have this class available at URL '/utils', and we want our

client-side namespace containing these methods simply to be called 'Remote.'



    >>> from extdirect.router import DirectProviderDefinition

    >>> print DirectProviderDefinition(TestUtils, '/utils', 'Remote').render()

    ... #doctest: +NORMALIZE_WHITESPACE

    

    Ext.Direct.addProvider({"url": "/utils",

        "namespace": "Remote",

        "type": "remoting",

        "id": "TestUtils",

        "actions": {"TestUtils": [{"name": "capitalize", "len": 1}, 

                                  {"name": "today", "len": 1}]}});

    



Now, assuming that, one way or another, we've provided this code to the client

and our class is available at that URL, we are now able to access these methods

from the browser:

    

    Remote.TestUtils.capitalize({word:'foo'}, console.log)



That example would make a call to the 'capitalize' method on our TestUtils

class and feed the result to our callback, which in this case merely prints the

result to the JS console.



Let's see how that would work from the perspective of the server. That call

would make a POST request with a JSON-encoded body, so let's create that

manually:



    >>> from extdirect.router import json

    >>> data = {"action":"TestUtils","method":"capitalize","data":[{"word":"foo"}],"type":"rpc","tid":1}

    >>> body = json.dumps(data)



Our class name is passed in as "action", the method name as "method", and

whatever data we sent as a single-member array containing a hash of our

parameters. For our purposes, "type" will always be "rpc". Ext.Direct requests

also provide a transaction id ("tid") which may be used as you see fit to

handle the possibility of stale data.



Now, let's make an instance of our server-side class:



    >>> utils = TestUtils()



This instance is callable and accepts the request body, and returns a

JSON-encoded object exhibiting the structure expected by Ext.Direct on the

client:



    >>> utils(body)

    '{"tid": 1, "action": "TestUtils", "type": "rpc", "method": "capitalize", "result": "FOO"}'



Notice the "result", which is what we'd expect. The client would decode this

object and pass the "result" value to the callback. Just for fun, let's check

out our other defined method:



    >>> data = {"action":"TestUtils","method":"today","data":[],"type":"rpc","tid":1}

    >>> body = json.dumps(data)

    >>> resultob = json.loads(utils(body))

    >>> print resultob['result']

    Today is Wednesday.



===========

Zope Router

===========



Using extdirect in Zope is extremely simple, due to a custom ZCML

directive that registers both a BrowserView for the server-side API and a

viewlet to deliver the provider definition to the client.



1. Define your class

   

   e.g., in myapi.py:



   from extdirect.zope import DirectRouter



   class MyApi(DirectRouter):



       def a_method(self):

           return 'A Value'



2. Register the class as a direct router



   



     



       



   



3. Provide the extdirect viewletManager in your template. 

   (Note: Ext is a prerequisite.)



    



4. Call methods at will!



    



      function a_method_callback(result){

          ... do something with result ...

      }



      MyApp.remote.a_method({}, a_method_callback);



    



=============

Django Router

=============



So, you have a Django app, and you want to add Ext.Direct. Here's how:



    1. Add 'extdirect.django' to INSTALLED_APPS in settings.py

    

    2. In a new file called direct.py, define your router class and register it:

    

            from extdirect.django import DirectRouter, register_router



            class MyRouter(DirectRouter):

                def uppercase(self, word):

                    return word.upper()

                def lowercase(self, word):

                    return word.lower()



            register_router(MyRouter, 'Remote')

        

       The arguments to register_router are the router class, the client-side

       namespace, and an optional url under /extdirect at which the router

       should be available (defaults to the name of the class).



    3. In the root URLconf, map the extdirect urls by adding:



        (r'^extdirect/', include('extdirect.django.urls'))



    4. Also in the root URLconf, add these two lines:



        import extdirect.django as extdirect

        extdirect.autodiscover()



    5. In your template, load the provider definitions:

        

            {% load direct_providers %}

            {% direct_providers %}



    6. That's it. You should now have access on that template to the remote

       methods:

            

            Remote.MyRouter.uppercase({word:'a word'}, callback);