django queries

django_queries.py

"""
python data structures: 
https://docs.python.org/2/tutorial/datastructures.html

reference pages
https://docs.djangoproject.com/en/1.5/

query filters
https://docs.djangoproject.com/en/1.5/ref/models/querysets/#methods-that-return-new-querysets

field lookups
https://docs.djangoproject.com/en/1.5/topics/db/queries/#field-lookups

LIST: python's collector workhorse (an 'array' in javascript)

        number_list = [1, 2, 3, 4, 5]

        slicing: 
            number_list[0] 
            number_list[3]
            number_list[1:2]
            number_list[-1]

        adding:
            number_list.append(6)

        counting:
            len(number_list)

DICTIONARY: the heart of objects and models: key-value pairs (an 'object' in javascript)

        person = {'first_name': 'John', 'last_name': 'Martin'}

        getting values:
            person['first_name'] returns 'John'

        seeing the keys:
            person.keys() returns ['first_name', 'last_name']

3 basic commands:

            dir()         -- this returns local variables, or the variables of an object named in the parens
            len()         -- this counts whatever is inside the parens 
            for ...       -- starts a loop that cycles through a collection of objects. example:

            for person in person_query:
                print person.name

"""
# to fire up a python session inside a django project:

python manage.py shell

# imports on the arrest-watcher server
from arrestee.models import Arrestee
from watchlist.models import Person
from crime_places.models import Place

# imports on the crime-watcher server
from crime.models import Incident, Agency
from places.models import Place, City, State, County, ZipCode

# helper function
def print_vals(obj):
    keylist = sorted([key for key in obj._meta.get_all_field_names()], key=lambda s: s.lower())
    try:
        print "%s model values for %s:\n" % (obj._meta.object_name, obj)
    except:
        pass
    for key in keylist:
        try:
            print "%s: %s" % (key, obj.__getattribute__(key))
        except:
            pass

header = [
    'first_name',
    'middle_name',
    'last_name',
    'name_suffix',
    'birth_date',
    'arrest_agency',
    'arrest_date',
    'arrest_location',
    'arrest_location_description',
    'gender',
    'race',
    'home_address',
    'home_city',
    'home_state',
    'home_zip',
    'transient',
    'employer',
    'occupation'
]

from csvkit import CSVKitWriter as ckw
x2 = Arrestee.objects.filter(
        booking_county__name='Hillsborough', 
        charge__description__contains='WRITTEN PROMISE').order_by('-arrest_date').distinct()

with open('written_promise.csv', 'w') as f:
    writer = ckw(f)
    writer.writerow(header)
    for each in x2:
        writer.writerow([each.__getattribute__(key) for key in header])