Archive for the 'Django' Category

IBM releases DB2 adapter for SQLAlchemy

Antonio Cangiano February 13th, 2008

A while ago I informally announced IBM’s intention to develop an SQLAlchemy adapter for DB2 and Informix IDS. Today, I’m happy to inform you that we have a first working release for DB2 on Linux, Unix and Windows (LUW). Support for Informix IDS is next (almost done), and after that, it will be System i and z/OS’ turn.

This release will surely excite those Pythonistas who can appreciate DB2 for what it is: one of the most powerful data servers in the world. Which, in its Express-C version, also happens to be gratis (”free as in free beer”). But there is more to it than just that.

IBM has in fact created a project on Google Code, for supporting Python development with IBM Data Servers. Aside from downloads and SVN access, this gives the project a nice public bug tracker which was missing up until this point. A Google Group was also created in order to have an easy to follow support mailing list, and I invite you to join it now.

With the switch to Google Code, there was also an update to the Python drivers (now version 0.2.5), which contain a few improvements and a bug fix for the egg that wasn’t working properly on Linux.

The project currently hosts the following components:

  1. The ibm_db Python Egg for Linux and Windows which contains:
    • The ibm_db driver: a C extension module that wraps IBM’s Data Server Driver for ODBC and CLI APIs and provides a Python client interface for the DB2 and Informix IDS databases.
    • The ibm_db_dbi: a Python coded module that relies on the ibm_db Python driver, and complies with the DB-API 2.0 specs.
  2. The ibm_db_sa: a Python coded adapter which implements the SQLAlchemy 0.4 API specification.

Please use the driver and/or the adapter for SQLAlchemy and let us know if you encounter any issues or have any feedback about it.

Installing Django with PostgreSQL on Ubuntu

Antonio Cangiano December 26th, 2007

This how-to is essentially the same as my previous one, only this time I’ve provided step-by-step instructions for installing Django with PostgreSQL on Ubuntu 7.10.

First and foremost, we are going to install Django from its svn repository, as opposed to obtaining the 0.96 release archive. The reason for this is that the trunk version implements a few new features. The development code is also rather stable and used by most people in production mode, even for sites like the Washington Post.

Install Subversion

sudo apt-get install subversion

Checkout Django

svn co http://code.djangoproject.com/svn/django/trunk django_trunk

Tell Python where Django is

Ubuntu already ships with Python 2.5.1, thus you won’t have to install it. You can verify this by running python in your shell (use exit() to get out of the python shell). What you need to do is inform Python about the location of your django_trunk directory. To do this create the following file:

/usr/lib/python2.5/site-packages/django.pth

Within this file, place only one line containing the path to your django_trunk folder. In my case, this is:

/home/antonio/django_trunk

Of course, change it to the full path location of the directory on your filesystem.

Add django-admin.py to your PATH

The bin directory within the django folder (which is inside django_trunk itself) contains several management utilities. We need therefore to add the following to the PATH (again, change it to your own location):

/home/antonio/django_trunk/django/bin

How you go about doing this, depends on the shell you are using, and I’m assuming you are able to export a shell variable on your own. In case you are using the bash shell (as I do) you could export it in .bashrc. Alternatively, you could just create a symlink to the utility django-admin.py in /usr/bin, but I recommend the former approach.

Install PostgreSQL and Psycopg2

sudo apt-get install postgresql pgadmin3 python-psycopg2

This will install PostgreSQL 8.2.5, PgAdmin III and the driver Psycopg2 for you. Most people at this point will ask, what’s the default password for PostgreSQL on Ubuntu? You can use the following instructions to set the password for the user postgres both in Ubuntu and within PostgreSQL:

sudo su -
passwd postgres
su postgres
psql template1

The last instruction should open the psql shell, where you can run the following:

ALTER USER postgres WITH ENCRYPTED PASSWORD ‘mypassword’;

Verify the installation

You should be all set now, but let’s verify this right away. Open the shell and run the following instructions inside the python shell (start off with the python command).

>>> import django
>>> print django.VERSION
(0, 97, ‘pre’)
>>> import psycopg2
>>> psycopg2.apilevel
‘2.0′

By running exit() get out of the python shell, and verify that django-admin.py is in your path:

django-admin.py
Type ‘django-admin.py help’ for usage.

If you obtain a similar output for all three of them, you are really set.

Where to go from here

Now that Django is installed, you can go read the Django Book 1.0 that’s available for free online. Something equally well done and useful is really missing from the Rails community. Above all, experiment, Django (and programming in general) is learnt by doing. The Definitive Guide to Django: Web Development Done Right is also available for purchase in its deadtree version, which just came out. It’s cheap and it’s already a best seller on Amazon. Despite the availably of a free version online, I like having paper versions of tech books so that I can read without staring at the monitor. Furthermore, I feel like rewarding the authors (who are also the framework creators), while encouraging publishing companies that are willing to allow authors to make their books available for free on the web. Well done guys!

How to install Django with MySQL on Mac OS X

Antonio Cangiano December 22nd, 2007

Installing Django on Mac OS X Leopard is supposed to be very straightforward, but if you are new to it, you may encounter a few puzzling questions and, in the case of MySQL, even a couple of headaches. I’m writing about this for the benefit of those of you who may attempt and struggle with this feat. MacPorts is not required for this how-to.

First and foremost, we are going to install Django from its svn repository, as opposed to obtaining the 0.96 release archive. The reason for this is that the trunk version implements a few new features. The development code is also rather stable and used by most people in production mode, even for sites like the Washington Post.

Checkout Django

svn co http://code.djangoproject.com/svn/django/trunk django_trunk

Tell Python where Django is

Mac OS X 10.5 already ships with Python 2.5.1, thus you won’t have to install it. You can verify this by running python in the Terminal (use exit() to get out of the python shell). What you need to do is inform Python about the location of your django_trunk directory. To do this create the following file:

/Library/Python/2.5/site-packages/django.pth

Within this file, place only one line containing the path to your django_trunk folder. In my case, this is:

/Users/Antonio/Code/django_trunk

Of course, change it to the full path location of the directory on your filesystem.

Add django-admin.py to your PATH

The bin directory within the django folder (which is inside django_trunk itself) contains several management utilities. We need therefore to add the following to the PATH (again, change it to your own location):

/Users/Antonio/Code/django_trunk/django/bin

How you go about doing this, depends on the shell you are using, and I’m assuming you are able to export a shell variable on your own. In case you are using the bash shell (as I do) then you should have a .profile file in your home directory. Alternatively, you could just create a symlink to the utility django-admin.py in /usr/bin, but I recommend the former approach.

Grab and install MySQL

I would normally recommend PostgreSQL, at least until we have DB2 on Mac, but I realize that many of you use and prefer MySQL, which also seems to be the only one that requires special instructions due to a few installation issues when trying to get MySQL and Python to work together. You can install MySQL by grabbing and running one of the packages that are available on the official site. Choose the one for x86 and Mac OS X 10.4.

Install the MySQLdb driver

Get MySQL-python-1.2.2.tar.gz from SourceForge. Please follow these exact instructions because the source code won’t compile out of the box and will give you the following error when trying to build it:

/usr/include/sys/types.h:92: error: duplicate ‘unsigned’
/usr/include/sys/types.h:92: error: two or more data types
in declaration specifiers
error: Setup script exited with error: command ‘gcc’ failed

Run the following:

tar xvfz MySQL-python-1.2.2.tar.gz
cd MySQL-python-1.2.2

At this point, edit the _mysql.c file and comment out lines 37, 38 and 39 as follows:

//#ifndef uint
//#define uint unsigned int
//#endif

Now, from the MySQL-python-1.2.2 folder run:

python setup.py build
sudo python setup.py install

If you still get an error (and only in that case) you’ll need to edit the site.cfg file within the same folder and set threadsafe = False, before running the two commands above once again.
If instead, you don’t receive an error but you see warnings about files not required on this architecture, don’t be concerned about them. The last step required is to create a symbolic link with the following command:

sudo ln -s /usr/local/mysql/lib/ /usr/local/mysql/lib/mysql

All these adjustments are required because we are building and installing the driver on Mac and not on Linux.

Verify the installation

You should be all set now, but let’s verify this right away. Open Terminal and run the following commands in the python shell (start this with the python command).

Verify that MySQLdb is correctly installed:

>>> import MySQLdb
>>> MySQLdb.apilevel
‘2.0′

Now, verify that Django is working:

>>> import django
>>> print django.VERSION
(0, 97, ‘pre’)

By running exit() get out of the python shell, and verify that django-admin.py is in your path:

django-admin.py
Type ‘django-admin.py help’ for usage.

If you obtain a similar output for all three of them, you are really set to write the next YouTube.

Where to go from here

Now that Django is installed, you can go read the Django Book 1.0 that’s available for free online. Something equally well done and useful is really missing from the Rails community. Above all, experiment, Django (and programming in general) is learnt by doing. The Definitive Guide to Django: Web Development Done Right is also available for purchase in its deadtree version, which just came out. It’s cheap and it’s already a best seller on Amazon. Despite the availably of a free version online, I like having paper versions of tech books so that I can read without staring at the monitor. Furthermore, I feel like rewarding the authors (who are also the framework creators), while encouraging publishing companies that are willing to allow authors to make their books available for free on the web. Well done guys!

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