It’s a Pluggable World

amol | September 8th, 2012 | Uncategorized | Comments

One of the new additions in TG2.1.4 has been the support for the so called pluggable applications, this is a really powerful and convenient feature that probably not enough TurboGears users started embracing.

For people that never used them, pluggable applications provide a python package that can be installed and “plugged” inside any existing TurboGears application to add new features. Django has been probably the first framework to bring this feature to Python world and TurboGears implementation tries to be as convenient by making pluggable applications identical to plain TurboGears applications and providing a “quickstart-pluggable” command that creates the application skeleton for you. Pluggable applications can be installed using easy_install or pip and they can off course depend on any other pluggable application they need.

This year, at EuroPython 2012, I have been pleased to present a talk about using TurboGears for rapid prototyping (both in Italian and English, you should be able to find the videos on EuroPython youtube channel), so I decided to dedicate a part of it to pluggable applications as they are actually the fastest way to rapidly prototype a project. With my surprise most the questions I received were about the EasyCrudRestController and not about pluggable applications.

While the EasyCrudRestController is definitively a powerful tool, it’s far from being the answer to all the web developments needs. In most of the applications you are going to develop, users will probably prefer consulting content from something more engaging than an administration table of database entries.

This month, to create a set of utilities that can help people with their everyday needs, I decided to ask guys that work with me to make every part of the web sites that they were writing as pluggable applications. The result of this experiment has been that most of the pluggable apps that I did in my spare time (tgapp-smallpress, tgapp-photos, tgapp-tgcomments, tgext.tagging and so on) ended being used in real world projects and started to improve exposing hooks and ways to customize their behavior for the project they were going to be used.

After a few weeks, new pluggables like tgapp-fbauth, tgapp-userprofile, tgapp-calendarevents, tgapp-fbcontest, tgapp-youtubevideo has seen light and developing the target application started becoming blazing fast: Just plug what you need and customize it.

Embracing this philosophy the last project I’m working on has an app_cfg.py file that looks like:

plug(base_config, 'tgext.debugbar', inventing=True)
plug(base_config, 'tgext.scss')
plug(base_config, 'tgext.browserlimit')
plug(base_config, 'registration')
plug(base_config, 'photos')
plug(base_config, 'smallpress', 'press', form='XXX.lib.forms.ArticleForm')
plug(base_config, 'tgcomments', allow_anonymous=False)
from XXX.lib.matches import MyKindOfEvent
plug(base_config, 'calendarevents', 'eventi', event_types=[MyKindOfEvent()])
replace_template(base_config, 'smallpress.templates.article', 
                              'XXX.templates.press.article')
replace_template(base_config, 'smallpress.templates.excerpt', 
                              'XXX.templates.press.excerpt')

Thanks to this our development process has really improved: whenever a developer finds a bug he just has to propose a patch for the target pluggable, whenever someone notices a missing index on a query he has just to add it to the given pluggable. All the websites under development improved like people were working on the same project.

While existing pluggables might be limited, buggy or slow I’m getting confident that they will continue to improve, and some day they will surpass whatever custom implementation I can think of. I think I’m going to heavily rely on pluggable applications for any future project sticking to only one rule: “make it opensource”. This way, apart from probably helping other people, I’m also improving my own projects through other people feedbacks, bug reports and patches to the pluggables I used.

So, next time you have to start a new project give a look at the TurboGears CogBin and check if there is a pluggable application that looks like what you need. If you find any issue or find space for improvements just fork it and send a pull request, or send an email on the TurboGears Mailing List I’ll do my best to address any reported issue thanking you for your feedbacks as I’m aware that you are actually improving any past and future project that relies on that pluggable.

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What’s new about Sprox 0.8

amol | August 16th, 2012 | Uncategorized | Comments

Today Sprox 0.8 got released, it is the first release to add ToscaWidgets2 support. Depending on which version of ToscaWidgets is available inside your environment Sprox will either use TW1 or TW2 to generate its forms.

Being mostly a TW2 oriented release it might seem that not a lot changed since the previous version, but a little gem is hidden between all the TW2 changes as Sprox now supports setting default behavior for models themselves using the __sprox__ attribute inside model declaration.

class Parent(DeclarativeBase):
    __tablename__ = 'parents'
 
    uid = Column(Integer, primary_key=True)
    data = Column(String(100))
 
class Child(DeclarativeBase):
    __tablename__ = 'children'
 
    class __sprox__(object):
        dropdown_field_names = {'owner': ['data']}
 
    uid = Column(Integer, primary_key=True)
    data = Column(String(100))
 
    owner_id = Column(Integer, ForeignKey(Parent.uid))
    owner = relation('Parent')

The previous code example makes Sprox use the Parent data field for selection fields when choosing the parent of Child entities.

Apart from making easier to share options between your AddRecordForm and EditableForm __sprox__ attribute opens a great way to customize the TurboGears admin.

By adding a __sprox__ attribute inside your models you will be able to change the TurboGears admin behavior without having to create a custom admin configuration. Setting __sprox__ attribute makes possible to change most sprox properties changing CrudRestController behavior, the same properties that are documented on sprox.org can be specified inside the __sprox__ attribute by simply removing the underscores.

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TurboGears future performances comparison

amol | March 21st, 2012 | Uncategorized | Comments

Recently I decided to give a quick benchmark for curiosity to the going to be branches of TurboGears2.

I quickstarted a simple genshi based application (plain turbogears2 quckstart) and then I created a plain controller method without template, to avoid counting the template generation overhead.

The application has been installed in three virtual environments: one with TG2.1.4, one with the development branch which is going to be TG2.2 and one with the development branch which is going to be TG2.3

The following graph reports the resulting requests/second that my pc has been able to serve on each turbogears version.

I have to admit that I’m quite happy with the results, the grow is steady and TG2.3 seems to be three times faster than the current turbogears while still being backward compatible (The benchmark application has been quickstarted with TG2.1.4 and ran without issues on all the three environments)

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Mastering the TurboGears EasyCrudRestController

amol | January 31st, 2012 | Uncategorized | Comments

One of the key features of TurboGears2 is the great CRUD extension. Mastering the CRUD extension can really make the difference between spending hours or just a few minutes on writing a web app prototype or even a full application.

The CRUD extension provides two main features, the CrudRestController which is meant to help creating totally custom CRUDs and the EasyCrudRestController which provides a quick and easy way to create CRUD interfaces.

I’ll focus on the EasyCrudRestController as it is the easiest and more productive one, moving forward to the CrudRestController is quite straightforward after you feel confident with the Easy one.

The target will be to create, in no more than 40 lines of controller code, a full featured photo gallery application with:

  • Multiple Albums
  • Uploads with Thumbnails Generation
  • Authenticated Access, only users in group “photos” will be able to manage photos
  • Contextual Management, manage photos of one album at time instead of having all photos mixed together in a generic management section

If you don’t already know how to create a new TurboGears project, start by giving a look at TurboGears Installation for The Impatient guide. Just remember to add tgext.datahelpers to dependencies inside your project setup.py before running the setup.py develop command.

I’ll start by providing a Gallery and Photo model. To store the images I’ll use tgext.datahelpers to avoid having to manage the attachments. Using datahelpers also provides the advantage of having thumbnails support for free.

from tgext.datahelpers.fields import Attachment, AttachedImage
 
class Gallery(DeclarativeBase):
    __tablename__ = 'galleries'
 
   uid = Column(Integer, autoincrement=True, primary_key=True)
   name = Column(Unicode(100), nullable=False)
 
class Photo(DeclarativeBase):
    __tablename__ = 'photos'
 
    uid = Column(Integer, autoincrement=True, primary_key=True)
    name = Column(Unicode(100), nullable=False)
    description = Column(Unicode(2048), nullable=False)
    image = Column(Attachment(AttachedImage))
 
    author_id = Column(Integer, ForeignKey(model.User.user_id)))
    author = relation(app_model.User, backref=backref('photos'))
 
    gallery_id = Column(Integer, ForeignKey(Gallery.uid))
    gallery = relation(Gallery, backref=backref('photos', cascade='all, delete-orphan'))

Now to be able to start using our galleries we will have to provide a place where to view them and a gallery management controller to create and manage them. Viewing them should be quite straightforward, I’ll just retrieve the galleries from the database inside my index method and render them. To access a single gallery I’ll rely on the datahelpers SQLAEntityConverter which will retrieve the gallery for us ensuring it exists and is valid. For the management part I’ll create an EasyCrudRestController mounted as /manage_galleries

from tgext.crud import EasyCrudRestController
 
class GalleriesController(EasyCrudRestController):
    allow_only = predicates.in_group('photos')
    title = "Manage Galleries"
    model = model.Gallery
 
    __form_options__ = {
        '__hide_fields__' : ['uid'],
        '__omit_fields__' : ['photos']
    }
 
class RootController(BaseController):
    manage_galleries = GalleriesController(DBSession)
 
    @expose('photos.templates.index')
    def index(self, *args, **kw):
        galleries = DBSession.query(Gallery).order_by(Gallery.uid.desc()).all()
        return dict(galleries=galleries)
 
    @expose('photos.templates.gallery')
    @validate(dict(gallery=SQLAEntityConverter(Gallery)), error_handler=index)
    def gallery(self, gallery):
        return dict(gallery=gallery)

Logging in with an user inside the photos group and accessing the /manage_galleries url we will be able to create a new gallery and manage the existing ones.

To configure how the crud controller forms should appear and behave the __form_options__ property of the EasyCrudRestController can be used. This property relies on the same options as Sprox FormBase and customizes both the Edit and Add forms.
The next part is probably to be able to upload some photos inside our newly created galleries. To perform this we will create a new EasyCrudRestController for gallery photos management.

from tgext.crud import EasyCrudRestController
from tw.forms import FileField
from tw.forms.validators import FieldStorageUploadConverter
from webhelpers import html
 
class PhotosController(EasyCrudRestController):
    allow_only = predicates.in_group('photos')
    title = "Manage Photos"
    model = model.Photo
    keep_params = ['gallery']
 
    __form_options__ = {
        '__hide_fields__' : ['uid', 'author', 'gallery'],
        '__field_widget_types__' : {'image':FileField},
        '__field_validator_types__' : {'image':FieldStorageUploadConverter},
        '__field_widget_args__' : {'author':{'default':lambda:request.identity['user'].user_id}}
    }
 
    __table_options__ = {
        '__omit_fields__' : ['uid', 'author_id', 'gallery_id', 'gallery'],
        '__xml_fields__' : ['image'],
        'image': lambda filler,row: html.literal('‹img src="%s"/›' % row.image.thumb_url)
    }

Mounting this inside the RootController as manage_photos = PhotosController(DBSession) it will be possible to upload new photos inside any gallery. To manage the photos inside the first gallery for example we will have to access /manage_photos?gallery=1url.

Each parameter passed to the EasyCrudRestController is used to filter the entries to show inside the management table and the keep_params option provides a way to keep the filter around. This makes possible to edit the photos of only one gallery at the time instead of having all the photos mixed together. Also when a new photo is created it will be created in the current gallery.

The PhotosController got more customization than the GalleriesController, through the __field_widget_types__ and __field_validator_types__ options we force the image field to be a file field and using the __field_widget_args__ we ensure that the newly uploaded photos have the current user as the author.

__table_options__ provide a way to customize the management table. The available options are the same as the Sprox TableBase and Sprox TableFiller objects. in this case we hide the indexes of the rows on the database and the gallery itself, as we are managing the photos of a specific gallery we probably don’t need to know which galleries the photos belong to. Using the __xml_fields__ we also specify that the image field provides HTML and so doesn’t have to be escaped. The image entry forces the table to show the image thumbnail for the image column of the table instead of printing the AttachedImage.__repr__ as it would by default.

At first sight it might sound a bit complex, but once you start feeling confident, the CRUD extension makes possible to create entire applications in just a bunch of code lines. With just a few lines of code we created a photo gallery with multiple albums support and we can now focus on the index and gallery templates to make the gallery as pleasant as possible for our visitors.

The complete implementation of the photo gallery is available as a pluggable application on bitbucket, feel free to use it in your TurboGears projects.

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Our First Hackathon

puria | January 16th, 2012 | Opensource, Software Development | Comments

Axant codes for food

Axant codes for food

We are coders, and we love to code. Our job is coding, and we have fun to.

Hence we decided to have fun, just by having a 24h non-stop coding experiment in our preferred and beloved Italian restaurant (well actually a taverna)!

We will have a mini-hackathon tomorrow at 3pm our time, to celebrate together the past 2011 working year, that was great! Free Food, free alcohol and a couple of cots is our necessaire for brainstorm and actuate our plan to take over the world!

Actually this “coding marathon” it has a subject, all the projects and ideas that will be developed should be related to “Food / Dining”!

The products result of the day, if useful, will be developed on field and used by a restaurant and a couple of bars, free of charge. Hence if there are good result could be a first step for a new free-software project.

In fact probably tomorrow we’ll not have just software projects cause the team is heterogeneous, built of lawyers, designers, creative people, musicians… and obviously coders!

The plan includes a couple of hours to study the problematics of a restaurant and in particular of our host. The owner will illustrate to us his business processes and we will try to understand were we could help them with our notions.

The next step is to actuate the thoughts into reality in the next 20hrs (: that’s it, nothing easier huh?

In the next post I’ll update the outcomes and the people behind it!

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TurboGears2 DebugBar

amol | November 12th, 2011 | Uncategorized | Comments

Recently some work has been done to extend the hooks support in TurboGears, to play a little with the new hooks I decided to try creating the famous and envied Django Debug Toolbar. I’m quite happy of the result and most of the features are there. In a few days I’ll be able to place it on a public repository and I’ll release it concurrently with the 2.1.4 release of TurboGears.

Debug Toolbar

Debug Toolbar

Timings

Timings

Request and Headers

Request and Headers

SQLAlchemy Queries

SQLAlchemy Queries

Mounted Controllers

Mounted Controllers

The code has been heavily inspired by the Pyramid Debug Toolbar and have to thank the Pyramid team for the good job they did at making the Toolbar code clean and simple.

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TurboGears2 Performance Improvements

amol | October 4th, 2011 | Uncategorized | Comments

As recently some effort has been involved in improving the performances of TurboGears2, I was curious to see how much things improved. As usually, the test isn’t really reliable in any way and was just for fun.

All the graphs report the request/sec the application has been able to perform on my computer with only 1 concurrent client. So higher is better.

Here is the comparison between TG2.0 and TG2dev (will be 2.1.4)

I also compared various setups with different template engines on TG2dev

The comparison happened on an application similar to the quickstarted one.
Actually as there is no database involved in this application the template engine impacts a lot and so was a good benchmark for the template engines themselves.

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ACRcms 0.3.5 released with libacr 0.7

amol | July 8th, 2011 | Uncategorized | Comments

New features introduced are:

  • Assets manager, Upload your videos and images using the Asset manager instead of the RDisk if you want to create slices from them. Assets manager will also create thumbnails for everything and will convert the videos to support HTML5
  • BlogPost view (an HTML view with a title)
  • Attributes for Pages and Slices
  • Hide Pages from menu with hidden=1 attribute
  • Reorder Pages in menu menu-weight attribute
  • Add metatag description to pages with description attribute
  • Automatic Database migrations, never care about changes to the schema when you upgrade acr again, it will be automatically upgraded by acr itself on first visit
  • Hide edit bars in edit mode to view the slice as a standard visitor
  • Abstraction layer for encoding data, now each view encodes using EncodedView, so that it will be possible to switch to any key/value encoding or store in the future

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TurboGears 2.1.1 released!

amol | June 19th, 2011 | Uncategorized | Comments

After a reflection moment caused by the need to think what will follow after the pylons and repoze.bfg merge in pyramid the TurboGears2 team has decide to gather up all its forces and give to TurboGears2 its own independent life.

The first steps have been oriented to improve the framework reliability and brought to life the TurboGears continuous integrations system and a standard project release process.

After a few months of work 2.1.1 has been released and it brings many fixes and improvements, 2.1.2 is under its way and a 2.2 release with major improvements is already planned!

TG2 Core:
* Fixed dependencies for Python 2.4. Now any packages that are
needed are automatically installed.
* Updated package requirements as high as possible.
* Verified nested RestControllers work as expected
* Added/fixed Kajiki support
* Ignore repoze.who_testutil when running nosetests
* Fixed import order for pylons.middleware
* Fixed crash when PYTHONOPTIMIZE is enabled
* Report a warning about ErrorMiddleware is disabled
* Fixed concurrency issues with use_custom_format
* Fixed 404 errors if a controller uses only custom formats
* Verified that user object is available inside of the error controller/template
* Fixed expansion of arguments on before/after calls
* Fixed wrong header response for 405 error
* Fixed WebOb version requirment. Newer version required
* Added test case to check for replace_header when called from WSGIApp
* Fixed issues with Content-Type header appearing multiples times on 204/205 responses
* Removed redundant hasattr checks on override_template
* Improved support for pylons 1.0 strict_c
* Fixed post traceback, now reports to Pylons correctly
* Added test case to check for spurious content type removal on empty content
* Fixed crash when content type header is missing
* Fixed crash when response Content-Type is set to None
* Fixed support for etags. Pylons 1.0 changes slightly, we support the correct version now
* Added dependency_links and setup.cfg allow_hosts: easy_install TurboGears2 now works
* Fixed DecoratedController. should not call super(), 2.6 revealed a problem
* Fixed Genshi output method. Use XHTML if none specified, instead of XML

TG2 Devtools:
* Fixed Python 2.4 compatibility issues. Dependencies are now automatically specified
* Updated package version requirements as high as possible
* Fixed about.html instructions about where the logo is found
* Set “zip_safe=False” by default in the templates now
* Tests fixed, now pass
* Added support for sqlalchemy-migrate
* Added option to choose config file
* Added archive_tw_resources command for projects
* Fixed deprecated redirect calls
* Set Genshi templating method by default to XHTML
* Adding dependency_links: easy_install tg.devtools now works

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Asynchronous and Background Tasks with TurboGears2

amol | May 2nd, 2011 | Uncategorized | Comments

Want to handle long operations in your web application without having your users wait for minutes?

If you are using turbogears2 you might find tgext.asyncjob useful. Asyncjob extension provides background method calls and helpers to manage your database queries in the asynchronous functions. Makes also easy to implement an AJAX progress bar for your long running operations.

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