When I save my form I perform validation of data that is defined in my model
def clean(self):
model = self.__class__
if self.unit and (self.is_active == True) and model.objects.filter(unit=self.unit, is_terminated = False , is_active = True).exclude(id=self.id).count() > 0:
raise ValidationError('Unit has active lease already, Terminate existing one prior to creation of new one or create a not active lease '.format(self.unit))
How can I trigger same clean method during simple update without a need to duplicate clean logic in my update view?(In my view I just perform update without any form)
Unit.objects.filter(pk=term.id).update(is_active=False)
update don't call the save method of your model and so it's not possible for django to raise ValidationError exceptions in this case.
You need to at least call the full_clean method of your model before doing the update.
Maybe like this ?
unit = Unit.objects.get(pk=term.id)
unit.is_active = False
try:
unit.full_clean()
except ValidationError as e:
# Handle the exceptions here
unit.save()
Reference: https://docs.djangoproject.com/en/1.11/ref/models/instances/#validating-objects
I am learning Django,looked into django validation but the below type i want.searched in google no result.
In my app,their are two character fields,i want it to be validate so that the conditons are,
1.Either any one of the field is entered.
2.It should validate the entered data are integer.
that means,both fields are not mandatory,but any one is mandatory and that mandatory field should accept number only.
How to do it in django.
class MyForm(forms.Form):
field_one = forms.IntegerField(required=False)
field_two = forms.IntegerField(required=False)
def clean(self):
cleaned_data = self.cleaned_data
field_one = cleaned_data.get('field_one')
field_two = cleaned_data.get('field_two')
if not any([field_one, field_two]):
raise forms.ValidationError(u'Please enter a value')
return cleaned_data
Using an IntegerField will validate that only numeric characters are
present, covering your blank space use case.
Specifying required=False on both fields allows either field to be left blank.
Implementing clean() on the form gets you access to both fields.
.get() will return None if the key isn't found, so the use of
any([field_one, field_two]) will return true if at least one of the
values in the list isn't None. If neither value is found, the
ValidationError will be raised.
Hope that helps you out.
I have a problem with a model's clean() method and basic field validation. here's my model and the clean() method.
class Trial(models.Model):
trial_start = DurationField()
movement_start = DurationField()
trial_stop = DurationField()
def clean(self):
from django.core.exceptions import ValidationError
if not (self.movement_start >= self.trial_start):
raise ValidationError('movement start must be >= trial start')
if not (self.trial_stop >= self.movement_start):
raise ValidationError('trial stop must be >= movement start')
if not (self.trial_stop > self.trial_start):
raise ValidationError('trial stop must be > trial start')
My clean() method checks whether certain values are in the correct range. If the user forget to fill out a field, e.g. movement_start, then I get an error:
can't compare datetime.timedelta to NoneType
I'm surprised that I get this error, since the original clean() function should be catching that missing entry (after all movement_start is a required field). So how can I the basic checking for missing values, and my custom check whether values are in certain ranges? Can this be done with model's clean() method, or do I need to use Forms?
EDIT1 to make it more clear: trial_start, movement_start and trial_stop are all required fields. I need to write a clean() method which first checks that all three fields have been filled out, and then, check whether the values are in a certain range.
The following code for example DOES NOT work, since trial_start might be empty. I want to avoid having to check for the existence of each field - django should do that for me.
class TrialForm(ModelForm):
class Meta:
model = Trial
def clean_movement_start(self):
movement_start = self.cleaned_data["movement_start"]
trial_start = self.cleaned_data["trial_start"]
if not (movement_start >= trial_start):
raise forms.ValidationError('movement start must be >= trial start')
return self.cleaned_data["movement_start"]
EDIT2 The reason that I wanted to add this check to the model's clean() method is that objects that are created on the python shell, will automatically be checked for correct values. A form will be fine for views, but I need the value check also for the shell.
I guess that's the way to go:
class TrialForm(ModelForm):
class Meta:
model = Trial
def clean(self):
data = self.cleaned_data
if not ('movement_start' in data.keys() and 'trial_start' in data.keys() and 'trial_stop' in data.keys()):
raise forms.ValidationError("Please fill out missing fields.")
trial_start = data['trial_start']
movement_start = data['movement_start']
trial_stop = data['trial_stop']
if not (movement_start >= trial_start):
raise forms.ValidationError('movement start must be >= trial start')
if not (trial_stop >= movement_start):
raise forms.ValidationError('trial stop must be >= movement start')
if not (trial_stop > trial_start):
raise forms.ValidationError('trial stop must be > trial start')
return data
EDIT the downside of this approach is, that value checking will only work if I create objects through the form. Objects that are created on the python shell won't be checked.
I know this is late, but to answer why this might be happening for people who end up here: There's no "original clean". The clean method is a hook for custom validation, so you are the one who provides its code. Not sure how OP was using the clean hook, but: After defining it you should be calling full_clean() over your models so that Django runs model validation in its entirety. See the details in the docs for the order in which it calls the different validation methods and such https://docs.djangoproject.com/en/1.11/ref/models/instances/#validating-objects (perhaps important to note: full_clean() isn't automatically called by a model's save() which is part of why when you use the shell and save straight away you'll be skipping the validation)
(note ModelForms also have various validation steps and will call a model's full_clean: https://docs.djangoproject.com/en/1.11/topics/forms/modelforms/#validation-on-a-modelform )
I'm struggling with a similar issue but with a ForeignKey. In your case, I would just check that the fields are not empty, and I would simplify your Boolean expressions:
class Trial(models.Model):
trial_start = DurationField()
movement_start = DurationField()
trial_stop = DurationField()
def clean(self):
from django.core.exceptions import ValidationError
if self.trial_start:
if self.movement_start and self.movement_start < self.trial_start:
raise ValidationError('movement start must be >= trial start')
if self.trial_stop:
if self.trial_stop <= self.trial_start:
raise ValidationError('trial stop must be > trial start')
if self.movement_start:
if self.trial_stop < self.movement_start:
raise ValidationError('trial stop must be >= movement start')
You can add the following code in your model:
def save(self, *args, **kwargs):
self.full_clean()
return super().save(*args, **kwargs)
With this wherever you create your object (form, view, shell, test) the validation will be called.
I am trying to create a custom cleaning method which look in the db if the value of one specific data exists already and if yes raises an error.
I'm using a model form of a class (subsystem) who is inheriting from an other class (project).
I want to check if the sybsystem already exists or not when i try to add a new one in a form.
I get project name in my view function.
class SubsytemForm(forms.ModelForm):
class Meta:
model = Subsystem
exclude = ('project_name')
def clean(self,project_name):
cleaned_data = super(SubsytemForm, self).clean(self,project_name)
form_subsystem_name = cleaned_data.get("subsystem_name")
Subsystem.objects.filter(project__project_name=project_name)
subsystem_objects=Subsystem.objects.filter(project__project_name=project_name)
nb_subsystem = subsystem_objects.count()
for i in range (nb_subsystem):
if (subsystem_objects[i].subsystem_name==form_subsystem_name):
msg = u"Subsystem already existing"
self._errors["subsystem_name"] = self.error_class([msg])
# These fields are no longer valid. Remove them from the
# cleaned data.
del cleaned_data["subsystem_name"]
return cleaned_data
My view function :
def addform(request,project_name):
if form.is_valid():
form=form.save(commit=False)
form.project_id=Project.objects.get(project_name=project_name).id
form.clean(form,project_name)
form.save()
This is not working and i don't know how to do.
I have the error : clean() takes exactly 2 arguments (1 given)
My model :
class Project(models.Model):
project_name = models.CharField("Project name", max_length=20)
Class Subsystem(models.Model):
subsystem_name = models.Charfield("Subsystem name", max_length=20)
projects = models.ForeignKey(Project)
There are quite a few things wrong with this code.
Firstly, you're not supposed to call clean explicitly. Django does it for you automatically when you call form.is_valid(). And because it's done automatically, you can't pass extra arguments. You need to pass the argument in when you instantiate the form, and keep it as an instance variable which your clean code can reference.
Secondly, the code is actually only validating a single field. So it should be done in a specific clean_fieldname method - ie clean_subsystem_name. That avoids the need for mucking about with _errors and deleting the unwanted data at the end.
Thirdly, if you ever find yourself getting a count of something, iterating through a range, then using that index to point back into the original list, you're doing it wrong. In Python, you should always iterate through the actual thing - in this case, the queryset - that you're interested in. However, in this case that is irrelevant anyway as you should query for the actual name directly in the database and check if it exists, rather than iterating through checking for matches.
So, putting it all together:
class SubsytemForm(forms.ModelForm):
class Meta:
model = Subsystem
exclude = ('project_name')
def __init__(self, *args, **kwargs):
self.project_name = kwargs.pop('project_name', None)
super(SubsystemForm, self).__init__(*args, **kwargs)
def clean_subsystem_name(self):
form_subsystem_name = self.cleaned_data.get("subsystem_name")
existing = Subsystem.objects.filter(
project__project_name=self.project_name,
subsytem_name=form_subsystem_name
).exists()
if existing:
raise forms.ValidationError(u"Subsystem already existing")
return form_subsystem_name
When you do form=form.save(commit=False) you store a Subsystem instance in the variable form but the clean method is defined in SubsystemForm. Isn't it?
I have model Foo which has field bar. The bar field should be unique, but allow nulls in it, meaning I want to allow more than one record if bar field is null, but if it is not null the values must be unique.
Here is my model:
class Foo(models.Model):
name = models.CharField(max_length=40)
bar = models.CharField(max_length=40, unique=True, blank=True, null=True, default=None)
And here is the corresponding SQL for the table:
CREATE TABLE appl_foo
(
id serial NOT NULL,
"name" character varying(40) NOT NULL,
bar character varying(40),
CONSTRAINT appl_foo_pkey PRIMARY KEY (id),
CONSTRAINT appl_foo_bar_key UNIQUE (bar)
)
When using admin interface to create more than 1 foo objects where bar is null it gives me an error: "Foo with this Bar already exists."
However when I insert into database (PostgreSQL):
insert into appl_foo ("name", bar) values ('test1', null)
insert into appl_foo ("name", bar) values ('test2', null)
This works, just fine, it allows me to insert more than 1 record with bar being null, so the database allows me to do what I want, it's just something wrong with the Django model. Any ideas?
EDIT
The portability of the solution as far as DB is not an issue, we are happy with Postgres.
I've tried setting unique to a callable, which was my function returning True/False for specific values of bar, it didn't give any errors, however seamed like it had no effect at all.
So far, I've removed the unique specifier from the bar property and handling the bar uniqueness in the application, however still looking for a more elegant solution. Any recommendations?
Django has not considered NULL to be equal to NULL for the purpose of uniqueness checks since ticket #9039 was fixed, see:
http://code.djangoproject.com/ticket/9039
The issue here is that the normalized "blank" value for a form CharField is an empty string, not None. So if you leave the field blank, you get an empty string, not NULL, stored in the DB. Empty strings are equal to empty strings for uniqueness checks, under both Django and database rules.
You can force the admin interface to store NULL for an empty string by providing your own customized model form for Foo with a clean_bar method that turns the empty string into None:
class FooForm(forms.ModelForm):
class Meta:
model = Foo
def clean_bar(self):
return self.cleaned_data['bar'] or None
class FooAdmin(admin.ModelAdmin):
form = FooForm
** edit 11/30/2015: In python 3, the module-global __metaclass__ variable is no longer supported.
Additionaly, as of Django 1.10 the SubfieldBase class was deprecated:
from the docs:
django.db.models.fields.subclassing.SubfieldBase has been deprecated and will be removed in Django 1.10.
Historically, it was used to handle fields where type conversion was needed when loading from the database,
but it was not used in .values() calls or in aggregates. It has been replaced with from_db_value().
Note that the new approach does not call the to_python() method on assignment as was the case with SubfieldBase.
Therefore, as suggested by the from_db_value() documentation and this example, this solution must be changed to:
class CharNullField(models.CharField):
"""
Subclass of the CharField that allows empty strings to be stored as NULL.
"""
description = "CharField that stores NULL but returns ''."
def from_db_value(self, value, expression, connection, contex):
"""
Gets value right out of the db and changes it if its ``None``.
"""
if value is None:
return ''
else:
return value
def to_python(self, value):
"""
Gets value right out of the db or an instance, and changes it if its ``None``.
"""
if isinstance(value, models.CharField):
# If an instance, just return the instance.
return value
if value is None:
# If db has NULL, convert it to ''.
return ''
# Otherwise, just return the value.
return value
def get_prep_value(self, value):
"""
Catches value right before sending to db.
"""
if value == '':
# If Django tries to save an empty string, send the db None (NULL).
return None
else:
# Otherwise, just pass the value.
return value
I think a better way than overriding the cleaned_data in the admin would be to subclass the charfield - this way no matter what form accesses the field, it will "just work." You can catch the '' just before it is sent to the database, and catch the NULL just after it comes out of the database, and the rest of Django won't know/care. A quick and dirty example:
from django.db import models
class CharNullField(models.CharField): # subclass the CharField
description = "CharField that stores NULL but returns ''"
__metaclass__ = models.SubfieldBase # this ensures to_python will be called
def to_python(self, value):
# this is the value right out of the db, or an instance
# if an instance, just return the instance
if isinstance(value, models.CharField):
return value
if value is None: # if the db has a NULL (None in Python)
return '' # convert it into an empty string
else:
return value # otherwise, just return the value
def get_prep_value(self, value): # catches value right before sending to db
if value == '':
# if Django tries to save an empty string, send the db None (NULL)
return None
else:
# otherwise, just pass the value
return value
For my project, I dumped this into an extras.py file that lives in the root of my site, then I can just from mysite.extras import CharNullField in my app's models.py file. The field acts just like a CharField - just remember to set blank=True, null=True when declaring the field, or otherwise Django will throw a validation error (field required) or create a db column that doesn't accept NULL.
You can add UniqueConstraint with condition of nullable_field=null and not to include this field in fields list.
If you need also constraint with nullable_field wich value is not null, you can add additional one.
Note: UniqueConstraint was added since django 2.2
class Foo(models.Model):
name = models.CharField(max_length=40)
bar = models.CharField(max_length=40, unique=True, blank=True, null=True, default=None)
class Meta:
constraints = [
# For bar == null only
models.UniqueConstraint(fields=['name'], name='unique__name__when__bar__null',
condition=Q(bar__isnull=True)),
# For bar != null only
models.UniqueConstraint(fields=['name', 'bar'], name='unique__name__when__bar__not_null')
]
Because I am new to stackoverflow I am not yet allowed to reply to answers, but I would like to point out that from a philosophical point of view, I can't agree with the most popular answer tot this question. (by Karen Tracey)
The OP requires his bar field to be unique if it has a value, and null otherwise. Then it must be that the model itself makes sure this is the case. It cannot be left to external code to check this, because that would mean it can be bypassed. (Or you can forget to check it if you write a new view in the future)
Therefore, to keep your code truly OOP, you must use an internal method of your Foo model. Modifying the save() method or the field are good options, but using a form to do this most certainly isn't.
Personally I prefer using the CharNullField suggested, for portability to models I might define in the future.
The quick fix is to do :
def save(self, *args, **kwargs):
if not self.bar:
self.bar = None
super(Foo, self).save(*args, **kwargs)
This is fixed now that https://code.djangoproject.com/ticket/4136 is resolved. In Django 1.11+ you can use models.CharField(unique=True, null=True, blank=True) without having to manually convert blank values to None.
Another possible solution
class Foo(models.Model):
value = models.CharField(max_length=255, unique=True)
class Bar(models.Model):
foo = models.OneToOneField(Foo, null=True)
I recently had the same requirement. Instead of subclassing different fields, I chose to override the save() metod on my model (named 'MyModel' below) as follows:
def save(self):
"""overriding save method so that we can save Null to database, instead of empty string (project requirement)"""
# get a list of all model fields (i.e. self._meta.fields)...
emptystringfields = [ field for field in self._meta.fields \
# ...that are of type CharField or Textfield...
if ((type(field) == django.db.models.fields.CharField) or (type(field) == django.db.models.fields.TextField)) \
# ...and that contain the empty string
and (getattr(self, field.name) == "") ]
# set each of these fields to None (which tells Django to save Null)
for field in emptystringfields:
setattr(self, field.name, None)
# call the super.save() method
super(MyModel, self).save()
If you have a model MyModel and want my_field to be Null or unique, you can override model's save method:
class MyModel(models.Model):
my_field = models.TextField(unique=True, default=None, null=True, blank=True)
def save(self, **kwargs):
self.my_field = self.my_field or None
super().save(**kwargs)
This way, the field cannot be blank will only be non-blank or null. nulls do not contradict uniqueness
For better or worse, Django considers NULL to be equivalent to NULL for purposes of uniqueness checks. There's really no way around it short of writing your own implementation of the uniqueness check which considers NULL to be unique no matter how many times it occurs in a table.
(and keep in mind that some DB solutions take the same view of NULL, so code relying on one DB's ideas about NULL may not be portable to others)