Hi,
I am trying to make a django model that will show data from different
other models as a single model. Kind of like a database view to a
database table.
My idea is to make a custom field that maps to another field in some
other model
code for fields.py is as follows
---------------------------------------------------------------------------------------
from django.db import models
from django.db.models import get_model
class ViewField(models.Field):
def __init__(self, *args, **kwargs):
model = get_model(kwargs['app'], kwargs['model'])
if '__' in kwargs['field']:
self.var_name, self.field_name = kwargs['field'].split
('__')
else:
self.var_name = ''
self.field_name = kwargs['field']
for field in model._meta.fields:
if field.name == self.field_name:
self._field = field
break
else:
return None
del(kwargs['app'])
del(kwargs['model'])
del(kwargs['field'])
super(ViewField, self).__init__(*args, **kwargs)
def db_type(self):
return self._field.db_type()
def to_python(self, value):
return self._field.to_python(value)
def get_db_prep_value(self, value):
return self._field.get_db_prep_value(value)
def get_db_prep_lookup(self, lookup_type, value):
return self._field.get_db_prep_lookup(lookup_type, value)
def formfield(self, **kwargs):
return self._field.formfield(**kwargs)
def get_internal_type(self):
return self._field.get_internal_type()
def value_to_string(self, obj):
return self._field.value_to_string(obj)
def contribute_to_class(self, cls, name):
return self._field.contribute_to_class(cls, name)
---------------------------------------------------------------------------------------
I ve also made a custom manager. its code is as follows
---------------------------------------------------------------------------------------
from django.db.models import get_model
class ViewModelManager(models.Manager):
def __init__(self, *args, **kwargs):
self._model = get_model(kwargs['app'], kwargs['model'])
del(kwargs['app'])
del(kwargs['model'])
super(ViewModelManager, self).__init__(*args, **kwargs)
def get_query_set(self):
return self._model.objects.get_query_set()
def get_empty_query_set(self):
return self._model.objects.get_empty_query_set()
def none(self):
return self._model.objects.none()
def all(self):
return self._model.objects.all()
def count(self):
return self._model.objects.count()
def dates(self, *args, **kwargs):
return self._model.objects.dates(*args, **kwargs)
def distinct(self, *args, **kwargs):
return self._model.objects.distinct(*args, **kwargs)
def extra(self, *args, **kwargs):
return self._model.objects.extra(*args, **kwargs)
def get(self, *args, **kwargs):
return self._model.objects.get(*args, **kwargs)
def get_or_create(self, **kwargs):
return self._model.objects.get_or_create(**kwargs)
def create(self, **kwargs):
return self._model.objects.create(**kwargs)
def filter(self, *args, **kwargs):
return self._model.objects.filter(*args, **kwargs)
def aggregate(self, *args, **kwargs):
return self._model.objects.aggregate(*args, **kwargs)
def annotate(self, *args, **kwargs):
return self._model.objects.annotate(*args, **kwargs)
def complex_filter(self, *args, **kwargs):
return self._model.objects.complex_filter(*args, **kwargs)
def exclude(self, *args, **kwargs):
return self._model.objects.exclude(*args, **kwargs)
def in_bulk(self, *args, **kwargs):
return self._model.objects.in_bulk(*args, **kwargs)
def iterator(self, *args, **kwargs):
return self._model.objects.iterator(*args, **kwargs)
def latest(self, *args, **kwargs):
return self._model.objects.latest(*args, **kwargs)
def order_by(self, *args, **kwargs):
return self._model.objects.order_by(*args, **kwargs)
def select_related(self, *args, **kwargs):
return self._model.objects.select_related(*args, **kwargs)
def values(self, *args, **kwargs):
return self._model.objects.values(*args, **kwargs)
def values_list(self, *args, **kwargs):
return self._model.objects.values_list(*args, **kwargs)
def update(self, *args, **kwargs):
return self._model.objects.update(*args, **kwargs)
def reverse(self, *args, **kwargs):
return self._model.objects.reverse(*args, **kwargs)
def defer(self, *args, **kwargs):
return self._model.objects.defer(*args, **kwargs)
def only(self, *args, **kwargs):
return self._model.objects.only(*args, **kwargs)
def _insert(self, values, **kwargs):
return self._model.objects._insert(values, **kwargs)
def _update(self, values, **kwargs):
return self._model.objects._insert(values, **kwargs)
---------------------------------------------------------------------------------------
To make a view of a model Visit, I have the following code
---------------------------------------------------------------------------------------
from fields import ViewField
from models import ViewModelManager
class VisitView(models.Model):
id = ViewField(app = 'patient', model = 'visit', field = 'id',
primary_key = True)
name = ViewField(app = 'patient', model = 'patient', field =
'patient__name')
fee = ViewField(app = 'patient', model = 'visit', field = 'fee')
_base_manager = ViewModelManager(app = 'patient', model = 'visit')
def __unicode__(self):
return '%s' % self.id
class Meta:
managed = False
---------------------------------------------------------------------------------------
I am new to django, so i dont know if my approach is correct.
Any guidance is welcome
peace
goto
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