TurboGears: Python on Rails?

gcantallopsr writes "If you liked Ruby on Rails and its 15m intro video (.mov) you will probably like TurboGears and its 20 minute wiki tutorial. (.mov) It shows you the development of a simple wiki in just 20 minutes, and there is a text version of the tutorial. TurboGears uses Python, SQLObject, CherryPy, Kid, MochiKit and some extra pythonic glue to help you to (in their own words) 'Create a database-driven, ready-to-extend application in minutes. All with designer friendly templates, easy AJAX on the browser side and on the server side, not a single SQL query in sight with code that is as natural as writing a function.'"

Comments

Re:no sql?

[quigonn]

It shows a high level of abstraction when you access the DB by simply loading/persisting objects instead of having to handle queries, result sets, records and all the other low-level stuff. And abstraction (in this case) is good, as it helps the developer concentrate on the relevant parts of the program.

SQLObject rocks!

[SimHacker]

One of the nicest features of SQLObject is that it insulates you from the peculiararities of the database's SQL syntax, so you don't need to put any SQL code directly into the Python code (but you can if you need to for efficiency or if you're willing to write non-portable code).

The SQL database abstraction layer is an important feature of SQLObject, that Ruby on Rails doesn't currently support -- you have to write database dependent SQL code mixed in with your Ruby code.

SQLObject lets you write generic SQL queries with normal Pythonic expressions and operators, which are automatically translated into the database dependent SQL syntax by the database driver. So you don't have to change any of your Python code to port it to a different database, and you don't have to mix together two different notations, or quote a bunch of SQL strings in your Python code. It's a much more "pythonic" way of database programming than raw SQL.

The great thing is that it's so convenient and the syntax is so simple, that you can use the interactive Python shell to browse and test out and edit your database. It's trivial enough to type in some Python code on the keyboard that loops over the results of a query, performs some complex logic, and validates and edits a bunch of rows in the database. Much more powerful and easier to use than anything you can do with raw SQL.

-Don

Re:SQLObject rocks!

[Trejkaz]

There's a reason why stored procedures are important, and it doesn't have anything to do with perceived performance increases from not having to re-parse the same SQL code every call (that's definitely a benefit, but it's minor). In this case, stored procedures shelter you from SQL injection attacks

Whereas this is true, it's also true that using "?" parameters for any user-entered values can solve the SQL injection problem just as well.

Scaling up, and scaling down

[DavidNWelton]

Ok, so some of these tools are not suitable for running Amazon. But guess what - most people are not running Amazon! A lot of people don't have the development resources that amazon has, either, so what they are really looking for is a sweet spot that lets them get going quickly, and will grow within reason.

I'm still mulling it over and working on it, but I talk some about "scaling down" in this article:

http://dedasys.com/articles/scalable_systems.html

You're right of course that you don't want stuff that falls over the first time traffic spikes a bit, but you absolutely must have something that you can use to produce a functional product. You can have the fanciest, most scalable system out there, but if you spend two months twiddling with XML config files, things just aren't going to work out.

Re:Does it scale?

[Scarblac]

if you want to do something for your professional career, don't waste your time with those kind of frameworks.

If you want to do something for your professional career, get familiar with as varied a collection of tools as you can. Know the pros and cons of each. Actually test their performance, make toy projects, steal ideas and patterns. Be opinionated, but prepared to honestly choose the best tool for the job you're given, and to explain why it is the best, to suits and to techies. A few hours getting to know something new is never wasted.

Re:Video software

[mykdavies]

What software do people use for making these neat videos?

vnc2swf

And to bring us (nearly) back on topic, the latest version is written in python!

Re:no sql?

[wootest]

Other people have answered in-depth, but the short answer is:

a) You do not need to worry about which vendor's dialect of SQL syntax you're using - provided you know how to create and populate the tables in any database system, you can switch at the drop of a hat if you need or want to.

b) Provided the layers are stable, it protects you from SQL query injections. The abstraction layer does the escaping for you.

c) Abstracted queries makes queries 'just another function/method call', and you get ordinary data structures back. This in combination with a) and b) and a competent framework (Rails, Django, TurboGears, Cake, Trax, WebObjects) makes coding much quicker as you don't have to keep the semantics of SQL and your database in mind - just the model itself.

There are *many* nuances to this, but the above three are some of the most pertinent ones. Peruse the other comments if you want to get in-depth.

Re:no sql?

[mixmasterjake]

Persistance layers are cool for a lot of reasons. Though, it definitely takes some getting used to for those of us who have developed a lot of SQL driven applications.

Don't let anyone fool you into thinking that a persistance layer will be less development work for you - I have found this to be untrue. I can use automated tools to get myself 80% of the way there. For anything substantial, though, it always seem to wind up being more work as I figure out how to configure & trick the persistance layer into giving me my data in the most efficient way. This can be frustrating when you know how to accomplish the same thing in 5 seconds using plain SQL. Maybe it's just me?

But, if you do manage to get over the hump, the benefit is that your business logic layer is very clean with no DB code whatsoever. If you use it properly, you can get 100% separation between these layers.

If you're using a strongly typed language, you get the added bonus of compile-time checks for certain illegal assigment errors. You don't have to fumble around with things like converting dates into SQL. You don't have to check for SQL injection. Lots of other little things.

Twisted

[jcr]

Also worth checking out: Twisted. I haven't had occasion to use it myself, but people I know swear by it.

-jcr

Re:Rails everywhere.

[arevos]

To me it seems like a silly exercise to replicate rails in python or what have you. Ruby is easy to pick up and a nice language to boot. Why bother really? Just learn ruby and get on board.

Whilst Rails is an excellent framework for web applications, I've found that it gets exponentially more difficult to work with when your database structures grow more complex than interconnected lists. I recently designed a double-booked accounts program in Rails, and whilst most of the code was simple to design, I quickly got bogged down in handling the accounts-tree and the double-booking of financial records. Here the documentation ran out, and I was forced to go through the Rails source to discover a solution to my problem, which turned out to be less than optimum.

Secondly, whilst I have done a fair bit of work in Ruby, I can't help but prefer Python. If there's little difference between Rails and, say, Turbogears, Django or Subway, then surely it comes down to personal preference. Python web frameworks appear to take a more piecemeal approach than Rail, which can provide a more flexible solution in certain situations.

Can't say I much like SQLObject's syntax, though; but CherryPy seems rather elegant.

Re:Perl on rails?

[holy zarquon's singi]

yeah, Maypole and Catalyst.

Re:Rails everywhere.

[Ian Bicking]

To me it seems like a silly exercise to replicate rails in python or what have you.

1. TurboGears is not a Rails clone.
2. Most parts of TurboGears existed before Rails: CherryPy, SQLObject, FormEncode (and Python of course).
3. Kid is most closely related to Zope Page Templates (from the Python world), not anything from Rails.
4. MochiKit has a certain relationship to Prototype (the Javascript library from Rails), and is compatible with it. However, it's not that the author particularly likes Prototype.

Rails has taught us some important lessons, but they aren't really technical lessons:

1. We shouldn't sit around and say "oh, those poor people using PHP/Java/etc, too bad they don't know about what you can do using X". Instead we should talk more loudly and insistently about the advantages of our platforms. If you do it right people will pay attention.
2. We haven't concentrated enough on full-stack integration. We've been overvaluing decoupled pick-and-choose components. Full-stack integration doesn't have to mean coupling -- it can just be a matter of presentation, and making sure tools are complimentary. Not all of the Python frameworks are coming at it from this direction, but TurboGears very much is.
3. Things like screencasts are nice.

After looking at various pieces of Rails, these lessons have stood out to me, but the particular technology in Rails has not. Sure, there are some good ideas, but nothing radical, and there's good ideas everywhere waiting to be mined. We're not beneath mining other people's ideas, but it does not follow that the result is merely a "replication" in part or in whole.

As for Ruby: I think the two languages are largely equivalent in terms of what you can do. I would not say the same about PHP or Java. As for Rails specifically, I think it is only ahead of Python options in the second derivative. With conscious players the second derivative doesn't mean a whole lot.