Notes on Django: Population Script

After my last Django post I happened across this population script from Tango with Django. So I’ve updated it and adapted it to my own needs. Ha, Screw You Technical Debt!

example models.py

class Genre(models.Model):
    name = models.CharField()


class Musician(models.Model):
    genre = models.ManyToManyField(Genre)  # Note the m2m field
    name = models.CharField()
    bio = models.TextField()
    alive = models.BooleanField()

example populate.py

import os


def populate():

    print 'Populating Database...'
    print '----------------------\n'

    username = 'uname'
    email = 'uname@domain.com'
    password = 'secret'

    blues = add_genre('Blues')
    jazz = add_genre('Jazz')

    add_musician('Billie Holiday',
                'Eleanora Fagan, professionally known as Billie Holiday, was \
                an American jazz musician and singer-songwriter. Nicknamed \
                "Lady Day" by her friend and music partner Lester Young, \
                Holiday had a seminal influence on jazz music and pop singing. \
                Her vocal style, strongly inspired by jazz instrumentalists, \
                pioneered a new way of manipulating phrasing and tempo.',
                False,
                blues, jazz)

    add_musician('Big Mama Thornton',
                "Willie Mae 'Big Mama' Thornton was an American rhythm and \
                blues singer and songwriter. She was the first to record \
                Leiber and Stoller's 'Hound Dog' in 1952, which became her \
                biggest hit. It spent seven weeks at number one on the \
                Billboard R&B charts in 1953 and sold almost two million \
                copies. However, her success was overshadowed three years \
                later, when Elvis Presley recorded his more popular rendition \
                of 'Hound Dog'. Similarly, Thornton's 'Ball 'n' Chain' had a \
                bigger impact when performed and recorded by Janis Joplin in \
                the late 1960s.",
                False,
                blues)

    add_musician('Ella Fitzgerald',
                'Ella Jane Fitzgerald was an American jazz singer often \
                referred to as the First Lady of Song, Queen of Jazz and \
                Lady Ella. She was noted for her purity of tone, impeccable \
                diction, phrasing and intonation, and a "horn-like" \
                improvisational ability, particularly in her scat singing.',
                False,
                jazz)


    create_super_user(username, email, password)

    print '\nCurrently Populated:'
    print '--------------------\n'

    for m in Musician.objects.all():
        for g in Genre.objects.filter(musician__name__startswith=m):
            print '- {0}: {1}'.format(str(m), str(g))

    print '\nSuperUser:', User.objects.get(is_superuser=True).username
    print '\n' + ('=' * 80) + '\n'


def add_genre(name):
    g, created = Genre.objects.get_or_create(name=name)
    '''
    get_or_create returns a tuple of (object, created), where
    the object is the db entry and created is a Boolean referring
    to whether the object was just created or not.  So, if nothing's
    gone wrong False will indicate the object already exists
    '''
    print '- Genre: {0}, Created: {1}'.format(str(g), str(created))
    return g


def add_musician(name, bio, alive, *genre):
    m, created = Musician.objects.get_or_create(name=name,
                                                bio=bio,
                                                alive=alive)
    m.genre.add(*genre)
    print '- Musician: {0}, Created: {1}'.format(str(m), str(created))
    return m


def create_super_user(username, email, password):
    '''
    for some reason get_or_create didn't work with creating the
    SuperUser so here is a try/except, with an IntegrityError
    raised if the SuperUser already exists
    '''
    try:
        u = User.objects.create_superuser(username, email, password)
        return u
    except IntegrityError:
        pass

if __name__ == '__main__':
    print '\n' + ('=' * 80) + '\n'
    import django
    os.environ.setdefault('DJANGO_SETTINGS_MODULE',
                          'Project.settings')
    django.setup()
    from app.models import Genre, Musician
    from django.contrib.auth.models import User
    from django.db import IntegrityError
    populate()  # Call the populate function, which calls the
                # add_genre and add_musician functions

And in our root project directory, where manage.py is, we run our script.

vagrant@django:~/shared/ProjectRootDirectory$ python populate.py
================================================================================

Populating Database...
----------------------

- Genre: Blues, Created: True
- Genre: Jazz, Created: True
- Musician: Billie Holiday, Created: True
- Musician: Big Mama Thornton, Created: True
- Musician: Ella Fitzgerald, Created: True

Currently Populated:
--------------------

- Billie Holiday: Jazz
- Billie Holiday: Blues
- Big Mama Thornton: Blues
- Ella Fitzgerald: Jazz

SuperUser: uname

================================================================================

So, buggering about with models and the database just got easier, now that it takes minutes to destroy it and rebuild it. Super.