Write Your Own Add-Ons to Customize Plone¶

In this part you will:

Create a custom python package ploneconf.site to hold all the code
Modify buildout to install that package

Topics covered:

mr.bob and bobtemplates.plone
the structure of eggs

Creating the package¶

Our own code has to be organised as a python package, also called egg. An egg is a zip file or a directory that follows certain conventions. We are going to use bobtemplates.plone to create a skeleton project. We only need to fill in the blanks.

Advertencia

bobtemplates.plone is still under heavy development. Questions and the package it creates might change significantly until Plone 5 is finished. For this training use the current master at https://github.com/plone/bobtemplates.plone/tree/b09362f

We create and enter the src directory (src is short for sources) and call a script called mrbob from our buildout’s bin directory:

$ mkdir src
$ cd src
$ ../bin/mrbob -O ploneconf.site bobtemplates:plone_addon

We have to answer some questions about the addon. We will press Enter (i.e. choosing the default value) for all questions except 3 (where you enter your github username if you have one) and 5 (Plone version), where we enter 5.0.

--> Author's name [Philip Bauer]:

--> Author's email [bauer@starzel.de]:

--> Author's github username: pbauer

--> Package description [An add-on for Plone]:

--> Plone version [4.3.4]: 5.0

--> Add example view? [True]:

--> Add a diazo-theme? [False]:

If this is your first egg, this is a very special moment. We are going to create the egg with a script that generates a lot of necessary files. They all are necessary, but sometimes in a subtle way. It takes a while to understand their full meaning. Only last year I learnt and understood why I should have a manifest.in file. You can get along without one, but trust me, you get along better with a proper manifest file.

Inspeccione el paquete¶

In src there is now a new folder ploneconf.site and in there is the new package. Let’s have a look at some of the files:

bootstrap-buildout.py, buildout.cfg, travis.cfg, .travis.yml, .coveragerc: You can ignore these files for now. They are here to create a buildout only for this egg to make testing it easier. Once we start writing tests for this package we will have another look at them.
README.txt, CHANGES, CONTRIBUTORS, docs/: The documentation, changelog, the list of contributors and the license of your egg goes in there.
setup.py: This file configures the package, its name, dependencies and some metadata like the author’s name and email adress. The dependencies listed here are automatically downloaded when running buildout.
src/ploneconf/site/: The package itself lives inside a special folder stucture. That seems confusing but is necessary for good testability. Our package is a namespace package called ploneconf.site and because of this there is a folder ploneconf with a __init__.py and in there another folder site and in there finally is our code. From the buildout’s perspective our code is in <your buildout directory>/src/ploneconf.site/src/ploneconf/site/<real code>

Nota

Unless discussing the buildout we will from now on silently omit these folders when describing files and assume that <your buildout directory>/src/ploneconf.site/src/ploneconf/site/ is the root of our package!

configure.zcml (src/ploneconf/site/configure.zcml): The phone book of the packages. By reading it you can find out which functionality is registered though the component architecture.
setuphandlers.py (src/ploneconf/site/setuphandlers.py): This holds code that is automatically run when installing and uninstalling our addon.
interfaces.py (src/ploneconf/site/interfaces.py): Here a browserlayer is defined in a straightforward python class. We will need it later.
testing.py: This holds the setup for running tests.
tests/: This holds the tests.
browser/: This directory is a python package (because it has a __init__.py) and will by convention hold most things that are visible in the browser.
browser/configure.zcml: The phonebook of the browser directory. Here views, resources and overrides are registered.
browser/views.py: xxx
browser/templates/demoview.pt: xxx
static/: A directory that holds static resources (images/css/js). The files in there will be accessible through URLs like ++resource++ploneconf.site/myawesome.css
profiles/default/: The folder contains the GenericSetup profile. During the training will put some xml files there that hold configuration for the site.
profiles/default/metadata.xml: Version number and dependencies that are auto-installed when installing our addon.

Including the package in Plone¶

Before we can use our new package we have to tell Plone about it. Edit buildout.cfg and uncomment ploneconf.site in the sections auto-checkout, eggs and test:

auto-checkout +=
    Products.PloneFormGen
    bobtemplates.plone
    ploneconf.site_sneak
#    starzel.votable_behavior
    ploneconf.site

parts =
    checkversions
    codeintel
    instance
    mrbob
    packages
    robot
    test
    zopepy

eggs =
    Plone
    Pillow

# development tools
    z3c.jbot
    plone.api
    plone.reload
    Products.PDBDebugMode
    plone.app.debugtoolbar

# TTW Forms (based on Archetypes)
    Products.PloneFormGen

# The addon we develop in the training
    ploneconf.site

# Voting on content
#    starzel.votable_behavior

zcml =

test-eggs +=
    ploneconf.site [test]

This tells Buildout to add the egg ploneconf.site. Since it is also in the sources section buildout will not try to download it from pypi but will expect it in src/ploneconf.site. fs allows you to add packages on the filesystem without a version control system, or with an unsupported one.

Ahora ejecute buildout para reconfigurar Plone con la configuración actualizada:

$ ./bin/buildout

Después de reiniciar Plone con ./bin/instance fg el nuevo complemento ploneconf.site está disponible para instalar como PloneFormGen o Plone True Gallery.

We will not install it now since we did not add any of our own code or configuration yet. Let’s do that.