filter none on django field

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I have a model Person which sometimes has nothing in the birth_date field. Here is an example:

(Pdb) dude = Person.objects.get(pk=20)
(Pdb) dude
<Person: Bob Mandene>
(Pdb) dude.birth_date
(Pdb) dude.birth_date == None
True

How do I filter these records that have birth_date == None?

I have already tried the following with no success:

1: "birth_date__isnull" does not work.

 Person.objects.filter(birth_date__isnull = True) 
 # does not return the required 
 # object.    Returns a record that have birth_date set to 
 # NULL when the table was observed in MySQL.

The following does not return the the record with id 20.

Person.objects.filter(birth_date = "")

How do I filter on a field being None? It seems NULL and None are different. When I see the data using sequel pro (mysql graphical client) I see "0000-00-00 00:00:00", and the following did not work either

(Pdb) ab=Patient.objects.filter(birth_date = "0000-00-00 00:00:00")
 ValidationError: [u"'0000-00-00 00:00:00' value has the correct format 
 (YYYY-MM-DD     HH:MM[:ss[.uuuuuu]][TZ]) but it is an invalid date/time."]

model

class Person(models.Model):
    person_no = models.IntegerField(primary_key=True)
    locationid = models.IntegerField(null=True, db_column='LocationID', blank=True) 
    address =  models.ForeignKey('Address', db_column = 'address_no')
    birth_date = models.DateTimeField(null=True, blank=True)
    class Meta:
       managed = False
       db_table = 'person'

NULL in mysql turns into None in python, so what you had with birth_date__isnull=True should be returning those that have birth_date as None.

Filtering for empty or NULL names in a queryset, class QuerySet (model=None, query=None, using=None, hints=None)¶. Usually when you'll interact with a QuerySet you'll use it by chaining filters. To make this  In this brief tutorial we’ll explore the simple methods and chain functionality Django offers to make model filtering of fields a breeze. Understanding Django Field Lookup Syntax. Before we get into the specific code examples to properly filter QuerySets, it’s important to understand how Django handles keyword argument syntax and how it


Hmm I'm not sure why 0000-00-00 00:00:00 is casted into None in this case but you can try to use exact:

Person.objects.filter(birth_date__exact=None)

(Converting `Foo.objects.filter(bar=None)` to an `IsNull` too early.), It makes it possible to refer to model field values and perform database class Aggregate (*expressions, output_field=None, distinct=False, filter=None, **extra)​  None, False and True all are available within template tags and filters. None, False, the empty string ('', "", """""") and empty lists/tuples all evaluate to False when evaluated by if, so you can easily do {% if profile.user.first_name == None %} {% if not profile.user.first_name %}


A bit of list comprehension could come in handy here:

persons = [person for person in Person.objects.all() if not person.birth_date]

QuerySet API reference | Django documentation, The filter instance will have a field name of price__gt and an exact lookup type. use initial values as defaults if data is not None: # get a mutable copy of the  Tag: python,django I have a end_date field on my news apps which is a facultative field. When a author is editing one of his new and erase the end_date, I set in the model the end_date to None.


Query Expressions | Django documentation, The callable receives a QuerySet , the name of the model field to filter on, and the null_label : The display label to use for the choice to filter by None values. field_name ¶. The name of the model field that is filtered against. If this argument is not provided, it defaults the filter’s attribute name on the FilterSet class. Field names can traverse relationships by joining the related parts with the ORM lookup separator (__). e.g., a product’s manufacturer__name.


Tips and Solutions, Dear all, Is there an option to set the default filter field and value to use if no parameter DecimalField): def clean(self, value): if value is None: return 4.0 return  The django-filter library includes a DjangoFilterBackend class which supports highly customizable field filtering for REST framework. To use DjangoFilterBackend, first install django-filter. Then add django_filters to Django's INSTALLED_APPS. pip install django-filter You should now either add the filter backend to your settings:


Filter Reference, Django developers widely use the filter() method to SELECT rows of the only those records (movies) that have year field value greater than or equal to 2012. our intuitive mind would suggest something like Movie.objects.filter(year=None) . If a string-based field has null=True, that means it has two possible values for “no data”: NULL, and the empty string. In most cases, it’s redundant to have two possible values for “no data;” the Django convention is to use the empty string, not NULL. One exception is when a CharField has both unique=True and blank=True set.