wiki:EggCookingTutorial/BasicEggCooking

Version 10 (modified by muness, 9 years ago) (diff)

typo in the last link (two #)

Egg cooking

Since Trac 0.9 it has been possible to write plugins for Trac to extend Trac functionality. Even better, you can deploy plugins as Python eggs that really makes plugin development fun.

This tutorial shows how to make an egg, successfully load an egg in Trac and in advanced topics how to serve templates and static content from an egg.

You should be familiar with component architecture and plugin development. This plugin is based on example in the plugin development article. Here we extend it a bit further.

Required items

First you need setuptools. For instructions and files see EasyInstall page.

You also need Trac 0.9. Download it from the TracDownload page.

Directories

To develop a plugin you need to create few directories to keep things together.

So let's create following directories:

./helloworld-plugin/
./helloworld-plugin/helloworld/
./helloworld-plugin/TracHelloworld.egg-info/

Main plugin

First step is to generate main module for this plugin. We will construct simple plugin that will display "Hello world!" on screen when accessed through /helloworld URL. Plugin also provides "Hello" button that is by default rendered on far right in main navigation bar.

So create helloworld.py in ./helloworld-plugin/helloworld/:

# Helloworld plugin

from trac.core import *
from trac.web.chrome import INavigationContributor
from trac.web.main import IRequestHandler
from trac.util import escape

class UserbaseModule(Component):
    implements(INavigationContributor, IRequestHandler)

    # INavigationContributor methods
    def get_active_navigation_item(self, req):
        return 'helloworld'
        
    def get_navigation_items(self, req):
        yield 'mainnav', 'helloworld', '<a href="%s">Hello</a>' \
                  % escape(self.env.href.helloworld())

    # IRequestHandler methods
    def match_request(self, req):
        return req.path_info == '/helloworld'
    
    def process_request(self, req):
        req.send_response(200)
        req.send_header('Content-Type', 'text/plain')
        req.end_headers()
        req.write('Hello world!')
        

Make it as a module

Since this is not enough, we need to make our simple plugin as a module. To do so, you simply create that magic __init__.py into ./helloworld-plugin/helloworld/:

# Helloworld module
from helloworld import *

Make it as an egg

Now it's time to make it as an egg. For that we need a chicken called setup.py that is created into ./helloworld-plugin/:

from setuptools import setup

PACKAGE = 'TracHelloworld'
VERSION = '0.1'

setup(name=PACKAGE, version=VERSION, packages=['helloworld'])

To make egg loadable in Trac we need to create one file more. in ./helloworld-plugin/TracHelloworld.egg-info/ create file trac_plugin.txt:

helloworld

First deployment

Now you could try to build your first plugin. Run command python setup.py bdist_egg in directory where you created it. If everthing went OK you should have small .egg file in ./dist directory.

Copy this .egg file to /[your trac env]/plugins directory. If you're using mod_python you have to restart Apache.

Now you should see Hello link at far right in main navigation bar when accessing your site. Click it.

Aftermath

Now you have successfully created your first egg. You can continue now reading EggCookingTutorial/AdvancedEggCooking to really integrate plugin into Trac layout.

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