class Trail(models.Model):
    '''
    Main model for this application.  Contains all information for a particular trail
    '''
    trail_name = models.CharField(max_length=150)
    active = models.BooleanField(default=True)
    date_uploaded = models.DateTimeField(default=now())
    owner = models.ForeignKey(Account, default=1)

class Surface(models.Model):
    '''
    A many to many join table to map a surface type to many trails.  A trail can have many
    surface types.
    '''
    type = models.CharField(max_length=50, db_column='surface_type', unique=True)
    trails = models.ManyToManyField(Trail)

    class Meta:
        ordering = ('type', )

from django.models.db import Q

queries = [Q(type = surface) for surface in request.GET.getlist('keys')]
query = queries.pop()

for item in queries:
     query |= item

results = Trail.objects.filter(surface=type)