Eighteen months of Django
dangoldin.com
dangoldin.com
celeryd is also good for scheduling tasks with either single or periodic execution.
http://docs.celeryproject.org/en/latest/getting-started/firs...
You can also use it in a typical task queue role. It will pickle or serialize the Python objects that accompany tasks for transmission over the wire.
celery is definitely nice, but it does have its limitations (like everything else).
I'm about to hit a point in my pet project where I need something but I havn't chosen my approach yet. I've ehard Pyres is better than Celery.
Celery does what it's supposed to; that's about all I can say for it. I'd suggest writing a few simple jobs and testing them in similar environments under as much load as you can. Look for things like consistency of logging and running tasks exactly once across multiple consumers despite the semantics of the queue you pick.
I never really saw the point of that part of celery anyway. Cron's perfectly adequate on its own (and installed just about everywhere).
I agree that you should keep the code itself in python, but that can be handled just by making it a management command that gets called by cron.
Sysadmins understand and love cron, too. I think celery reinventing the wheel might make some of them a bit mad.
- being able to modify the task frequency from the admin
- cron needs special care with setting the environment variables like PATH
Python is now my language of choice for "getting shit done".
I write this not to meaninglessly bash PHP but to hopefully convince even a single developer passing by to try out Python. I thought the same thing as you, passer-by dev, once: "Why do I need Python? It's stupid. It uses whitespace weirdly. I can do whatever I need in PHP." But then you realize you could be doing everything you're doing in PHP... better, smarter, and faster.
- hosting on heroku
- static files on Amazon S3
- virtualenv(wrapper) isolated packages
- environment and security critical variables removed from settings.py and stored as environment variables (following the 12-factor design ethic)1. Why not use django-admin.py startproject --template=<url>? I typically do something like django-admin.py startproject --template=https://github.com/rdegges/django-skel/zipball/master mynewproject so I don't actually have to clone
2. No runtime.txt for heroku?
3. Not specifying version numbers in your requirements.txt is very dangerous. I prefer something like "Django>=1.5.0,<=1.5.9"
I made a skeleton project for me as I couldn't find a decent guide for deploying django static's on s3. I fumbled my way through it and corrected and formalised it later so I could do it again. The https://github.com/rdegges/django-skel project looks really useful as it contains everything and more you might want to use for a django project (and more), though not yet knowing what magic's it's doing I wouldn't yet jump to use.
1. That is very neat. I hope to try and copy that.
2. Noted. I didn't realise the need, as python 2.7.4 is the default. Can see it causing headaches if this were to change however.
3. Why is it dangerous? I preferred to keep the version numbers so it would always just install latest versions without any extra effort.
I like to try and scope the package versions at the level the maintainer promises not to introduce breakages at.
This allows the virtualenv to depend on packages provided by your distro instead of trying to compile its own. Wherever possible, I try to do this with Python packages that require a C compiler to make deployment a little easier and reduce dependencies.
Personally, I'm not a fan of Fabric and I much prefer configuration management (Salt, Chef, Puppet) because of the added flexibility you get. About the most I use Fabric for is logging into the Salt Master and kicking off a deployment process.
Never ever ever mix/depend upon system packages in your virtualenv. Ever.
Some examples:
* PIL - Using Pip's version on Ubuntu, you have to hack your directory structure and re-compile the whole thing or PIL doesn't compile in support for your image libraries.
* psycopg2 - This is hit and miss (OS X comes to mind), but depending on the system version guarantees that it has been tested to work with the specific version of Postgres on your system.
* Crypto libraries - Broken packages have ended up on Pip and just cause a bloody headache. The system package is, again, tested and works.
Compiling a DEB/RPM would be a good idea, but it's not a well supported system at all. If there were a simple pip compile --type=deb or something, we would be all over it.
Psycopg2 - Well, it's just a client library - surely you will be making sure your client matches your server's version (whether that's local or a clust or whatever)? Sure your system will likely need Postgres headers installed, but why is that an issue? Actually, let me just check that. e: Yeah, you need libpq-dev installed, but I fail to see the point here? You need to make sure you have python-dev and a correct version of Python installed, too.
PyCrypto - Hmm, not had a problem with this hugely.
What I was suggesting doesn't involve a deb of individual packages, but a deb of the entire app/virtualenv.
- Gargoyle: Feature switches in Django https://github.com/disqus/gargoyle
- webassets and django-assets: For minifying static assets
- raven + sentry for logging. Sentry is the server, so actually can be used with any project, not only Django.
- django_extensions: Provides some helper management commands, for example manage.py shell_plus which automatically imports your models
- dbbackup for backing up your db to S3 or Dropbox
Of course this means you'll have to keep track of where the uploaded file is currently located, but if you ever want to scale to multiple web servers you'll need to do that anyway.
See http://philfreo.com/blog/how-to-allow-direct-file-uploads-fr... for a Python example.
If it's relatively simple and you don't really want to deal with user registration/databases I'd say definitely go with Flask. Django does a pretty good job of those two but until it "clicks" you end up being confused.
Django is definitely more in the range of "we want you to write" this way but I've found it to be at least a bit more customizable than RoR. Flask is on the other extreme which lets you do whatever you want.. but you're the one who has to do it.
"However Flask is just not designed for large applications or asynchronous servers. Flask wants to make it quick and easy to write a traditional web application."[1]
Flask is excellent when you just don't need a bunch of the stuff in Django, and don't need the batteries to be included. It's not so much that Flask is suitable to high-complexity apps, but more that it's suited to highly custom web apps. Building a music sharing app based on jQuery mobile and backed by Mongo? You're better off with Flask. But at scale you're going to end up doing something custom.
Django is highly suitable if you need to manage users, have a variety of entities that lend themselves to the admin dashboard (more broadly, that the admin/public app metaphor even makes sense in the first place), and find a plug-and-play package system compelling.
They are both great frameworks, but "complexity" (advanced/simple) is the wrong axis along which to evaluate them.
The documented limitation you reference is based on the WSGI server being used. "If your server uses some kind of concurrency that is not based on threads or greenlets, Flask will no longer be able to support these global proxies."[0] As nginx+gunicorn is becoming more popular, this isn't really an issue at all.
[0]http://flask.pocoo.org/docs/becomingbig/#scale-like-a-pro
Armin has said before that he needs to update/clarify that statement -- as dvanduzer said, it's not really relevant anymore.
They just wanted a simple web form, where the sales people could add notes throughout the day and then automatically email those notes to the owner at the end of the day.
I first tried Django and was quickly overwhelmed.. I switched to Flask and with the help of flask-login, flask-wtforms, and flask-mail, it only took me a long weekend to get it up and running.
Just a personal anecdote, but Flask was much easier for me.
This doesn't make it better, but it also doesn't make it worse.
Django is great if you're making a standard cms type website. News feed, blog, etc. There's a bit of a learning curve but it gives you a lot of the scaffolding out of the box (and there are loads of examples to learn from). It has the biggest community (I guess?) so you'll always be able to find answers / libraries / sample code.
Use Flask if you really want to get a website up and running with half a dozen lines of code. You'll have to build everything else yourself; admin, authentication, etc etc - though there are good extensions for a lot of things too.
Thinking about it - if you don't know either of them, spend a day with Flask, by the end of it you should have a fairly good idea of what you get with it. Then run through the Django tutorials. It'll take longer but you'll be impressed with how quickly you can get something fairly complete up and running.
For me, I lean towards Flask (heavily). When you think about what Django does - it's basically a web container with a db/model layer and sensible scaffolding for the views (front and admin). I prefer to use SQLAlchemy (if I'm working with a relational db). In terms of the admin I think that the days of writing admin grid and edit screens that post back and forth to the server are numbered (I use REST and Angular now) - so that's not a bit of Django I use either. By the time you've ripped all that out you may as well save yourself all the config and just use Flask. Having said that - LEARN THEM BOTH. At least just a little bit so you can see for yourself where each one shines.
These days I approach it completely differently. My last two projects have involved a fair amount of complex business logic (and processing work). I've written the libraries I needed first as standalone packages, only introducing Flask as a final step. The web wrapper is just there to provide a web interface (mostly an api) access the db layer and glue it all to my libraries. I'd recommend this approach as it stops you from thinking along the lines of "ok, I'll need to create 3 Django apps, here are my models for each, should I put this code in the models.py or the views.py?" Instead you concentrate on making the real python code to do the heavy lifting, and you architect that sensibly without having to worry about how the web framework would normally prescribe it to be done. You'll end up with far more portable code in the long run.
The creator and lead developer, Massimo Di Pierro, is incredibly active and always willing to lend a hand with whatever problem you have. I've seen him around reddit (not sure if he's on HN) and even when he's met with the inevitable haters, he's always been friendly and cordial.
Just like you've said, web2py was originally made to teach people how to build websites, which really shows in its architecture. It forgoes traditional Python conventions ("explicit is better than implicit" being a major one) in order to be more beginner-friendly. Some of the more experienced developers find this annoying, but if you're coming from PHP or a fresh background, it can be much easier to get started. Just take a look at the overview on Wikipedia[0]. It gives a good outline.
This is coming from someone who doesn't even use web2py. I prefer Flask for personal projects and Django for work/group things, but I would whole-heartedly recommend web2py. Run through the book[1] and, if you don't like it, give the Django tutorial[2] a shot. If that doesn't mesh with you, there's Flask[3], Pyramid[4], TurboGears[5], and CherryPy[6]. (The last two I would not recommend for beginners, but they're still good!)
[0]: http://en.wikipedia.org/wiki/Web2py#Overview
[2]: https://docs.djangoproject.com/en/1.5/intro/tutorial01/
[3]: http://flask.pocoo.org/docs/
[4]: http://docs.pylonsproject.org/projects/pyramid/en/1.4-branch...
My feeling too. Are there any projects which are starting to create the boilerplate for this? I'm new to Angular, so looking for where to get started...
It should be possible to build a completely generic frontend that just has a grid view and an edit view that you could wire to any REST backend. Then you could use flask-restful or Django Rest Framework or whatever else you wanted.
If you were going to go that route there's an angular directive for doing grids that would get you half way there: http://angular-ui.github.io/ng-grid/#/examples
Were I still building CMSs that's the approach I would be looking into.
Also Heroku has been mostly a godsend, as I haven't had to spend nearly any time on sysadmin stuff. One thing that caught me early on, not sure if it's a bug or what, but in Heroku, if you use git URLs for some of your packages in pip requirements (which is useful if you need to customize a package or more frequently fix a bug and can't wait for it to be pushed to pypi), Heroku's package cache has trouble knowing when to update unless you a) change the package version in its setup.py (may or may not be a good idea) or b) change the Python version in runtime.txt (kind of a pain as generally that means two deploys for an update, bump down one minor, then back up).
However, for large web projects, Django beats it hands down. Doing similar work with Flask would require so much wheel-reinvention that it'd be hard to justify your time or your client's money when it's all built quite well already.
Of course it's not perfect, and it's not for everything. But it's a great general-purpose, medium-performance web framework. It becomes a pain on very high-traffic sites (perhaps more so than JVM-based solutions and on par with scaling Ruby frameworks), but if you use it in the right place and/or team up with systems people that know their stuff, it's a powerful tool for quickly building complex websites in a maintainable and intuitive way.
IronPython?
I've just implemented one of these in PHP using the 'old' Symfony 1.4 and it was painful. I ended up hardcoding most of the frontend, and writing ridiculous modifications for "add another row" and validation.
Is Django any better at that? Complex forms have been my pain point for over 11 years, and if a framework handles them... I'm in!
Would love to know the best way people handle this.
In that case, I tend to use class-based views and set different forms, templates etc. depending on those values. If the form is different enough, it's easier just to send them to a completely different URL.
This is what I mean: an adaptive form http://screencast.com/t/SutggDU5
The server-side validation has to adapt depending on the data coming from the client-side, and varies a lot.
Perhaps others don't build forms like this much and so web frameworks don't deal with them; I get one like this every few months!
I still think a solution is to use multiple forms and form types rather than one big form. Perhaps you can prefix the field names on the template and use that to determine which form they go to inside the view. It makes your logic a little simpler in any case.
Multi-step forms can be implemented in Django using Form wizards [1]. In order to optionally show fields or make them required I think you could build it easily using the WizardView.get_form method [2]. The functionality to skip steps is built-in and it's very easy implement using conditional views [3].
In conclusion, it's fairly easy to implement the functionality you described using only the core framework without the need to rely on external packages.
[1] - https://docs.djangoproject.com/en/dev/ref/contrib/formtools/... [2] - https://docs.djangoproject.com/en/dev/ref/contrib/formtools/... [3] - https://docs.djangoproject.com/en/dev/ref/contrib/formtools/...
Have you seen anything saying it helps to build adaptive forms like [1]?
However, the way I would go about building something like that is by using the form wizard (mentioned in my previous comment) with a combination of forms/modelforms [1] and formsets [2]. Formsets are used in situations when you need to display the same form multiple times on the same page (like the multiple addresses/benefits income in your example). However, you would have to implement all the client side interaction yourself since Django does not provide this by default (there are some libraries which are supposed to help with this but I haven't tried them myself [3]).
One thing worth mentioning is that by default, the form wizard only allows you to display either a Form, or a Formset in a step/page. However, there is a ticket open for this [4] which links to a helper class: form_container.py [5] which helps overcome this problem. Hopefully, this will be included in future versions of Django.
Hope this helps.
[1] - https://docs.djangoproject.com/en/dev/topics/forms/modelform... [2] - https://docs.djangoproject.com/en/dev/topics/forms/formsets/ [3] - https://code.google.com/p/django-dynamic-formset/ [4] - https://code.djangoproject.com/ticket/18830 [5] - https://code.djangoproject.com/attachment/ticket/18830/form_...
It would be great if there was a ready-made add-on combining all these areas but I don't know any personally. I also suspect think that writing such a generic helper might not be a great idea as everyone needs something a bit different, so using the mentioned lower level components and combining them on your own could be the best way to go here.
I'm in the process of writing a pet project using Django and would really appreciate your insights on what packages you find useful (as mentioned at the bottom of your post).
It's not a Python package in the sense that you might mean, but using virtualenv is absolutely fundamental to good Python development (at least the kind that lets you keep your sanity).
South is also exceptional; however, the developer recently ran a successful Kickstarter campaign dedicated to creating an improved version intended to be merged with Django itself, so that's something to watch for.
Django-CMS has proven invaluable for many of my projects and clients, though it's very heavy and more of a project-tacked-on-to-your-project than just a package. It's great to know, though, and very powerful.
django-registration can be useful if you're into full-on user profile usage, though many sites don't actually need this. There's a separate project that provides a set of default templates for this package, and it's almost more useful than django-registration itself.
livesettings is an outgrowth of django-cms that's pretty useful when you need what would otherwise be settings.py constants that can be modified at runtime without a deployment and server restart. Be careful, though, as overuse of this means you might have design issues.
feedparser is a very, very easy way to consume XML feeds.
If you want to parse something in a very user-friendly way, BeautifulSoup is hard to beat. If you're into the nitty gritty and/or need serious performance, lxml serves the same purpose but kicks far more ass.
If you need to interface with Amazon's AWS environments (EC2, S3, etc.), boto is a brilliant library.
These are more Python-in-general than Django-specific, but that's often a good thing.
While all suggestion are useful the biggest take away for me is livesettings. TBH I can't think of how I would use it at the moment but I can see that it could come in handy later.
If your system gets updated/upgraded to the point where your virtualenv breaks, rebuild it from scratch; all it should take is a bit of time.
[edit: I am not a developer involved with virtualenv, and the statement about what it's intended for probably shouldn't be quite so strong, as this is only my impression of it and the way I use it.]
checkout virtualenvwrapper (http://virtualenvwrapper.readthedocs.org/en/latest/install.h...) as well for handling virtualenvs.