from django.contrib.gis.db import models

from django.contrib.localflavor.us.models import USStateField

class Location(models.Model):

    point = models.PointField()

    objects = models.GeoManager()

    def __unicode__(self): return self.point.wkt

class City(models.Model):

    name = models.CharField(max_length=50)

    state = USStateField()

    location = models.ForeignKey(Location)

    objects = models.GeoManager()

    def __unicode__(self): return self.name

class AugmentedLocation(Location):

    extra_text = models.TextField(blank=True)

    objects = models.GeoManager()

class DirectoryEntry(models.Model):

    listing_text = models.CharField(max_length=50)

    location = models.ForeignKey(AugmentedLocation)

    objects = models.GeoManager()

class Parcel(models.Model):

    name = models.CharField(max_length=30)

    city = models.ForeignKey(City)

    center1 = models.PointField()

    # Throwing a curveball w/`db_column` here.

    center2 = models.PointField(srid=2276, db_column='mycenter') 

    border1 = models.PolygonField()

    border2 = models.PolygonField(srid=2276)

    objects = models.GeoManager()

    def __unicode__(self): return self.name

# These use the GeoManager but do not have any geographic fields.

class Author(models.Model):

    name = models.CharField(max_length=100)

    objects = models.GeoManager()

class Book(models.Model):

    title = models.CharField(max_length=100)

    author = models.ForeignKey(Author, related_name='books', null=True)

    objects = models.GeoManager()