I'm trying to perform some custom validation on a model and I'm getting confused. Let me be specific. Let's say my code is as follows:
class FooManager(models.Manager):
def create_foo(self, name):
return self.create(foo_name = name)
class Foo(models.Model):
foo_name = models.CharField(max_length=30)
objects = FooManager()
def clean(self):
...
def save(self, *args, **kwargs):
self.full_clean()
super(User, self).save(*args, **kwargs)
Now, when I am working with this model from the shell, if I call:
f = Foo.objects.create_foo("")
It will raise a validation error before I get a chance to call save() on f. Why does this happen? Shouldn't the validation error only be raised once I call f.save()?
Note: the same thing happens if I use objects.create() as opposed to the custom defined create method. Any help would be greatly appreciated, as I'm finding validations in django to be fairly frustrating.
create() will automatically save, so even if you fix your error - you will still have to make sure the arguments to create fulfill the database requirements to save a record.
You forgot to put self in your manager
class FooManager(models.Manager):
def create_foo(self, name):
return self.create(foo_name = name)
Related
I am using a third party application and i wish to override the save() method of the original model to validate some data.
class CustomState(State):
class Meta:
proxy = True
def save(self, *args, **kwargs):
print('hellooo in save method of state')
super(State, self).save(*args, **kwargs)
However the code snippet above does not run.
Therefore my question is is there a way to override the save method of a model ? Or if thats not possible , is there a way to add in validation before the third party model instance is created?
the issue has nothing to do with the fact that your Model is proxy but the wrong way how you call the parent super().save():
class CustomState(State):
class Meta:
proxy = True
def save(self, *args, **kwargs):
print('hellooo in save method of state')
# The wrong way to call super
# super(State, self).save(*args, **kwargs)
super(CustomState, self).save(*args, **kwargs)
have a look at this tutorial, topic A super() Deep Dive
I guess what I need to do it overwrite my model's save method but do correct me if I'm wrong/have better suggestion.
This is what my model looks like:
class MergingModel(models.Model):
some_field = models.TextField()
And this is the unit test that I want to pass:
class MergingModelTests(TestCase):
def test_duplicates_are_overwriten(self):
MergingModel.create(id=1)
MergingModel.create(id=1, some_field="abc")
self.assertEquals(MergingModel.objects.count(),1)
self.assetEquals(MergingModel.objects.get(id=1).some_field,"abc")
I tried overwriting save method to check if record with id=x exists but that raised recursion errors, my code for save method looked like:
def save(self, *args, **kwargs):
if MergingModel.objects.filter(id__exact=self.id):
original = MergingModel.objects.get(id=self.id)
original.some_field = self.some_field
original.save()
else:
super().save( *args, **kwargs)
Then I tried overwriting create but I get error:
Key (id)=(ID1) already exists
So I'm not really sure what to do anymore.
I have a model with a custom save function, where I want to perform certain functions based on a condition like this:
class ClassName(models.Model):
def save(self, *args, **kwargs):
reindex = **kwargs.pop("reindex")
super().save(*args, **kwargs)
if reindex:
People.objects.create()
Now inside a task I want to call the following:
kwargs = { "reindex": False}
ClassName.objects.get_or_create(**kwargs)
When it does a create, it obviously runs the save function, but it's giving me an error saying reindex is not a field.
I have been researching it for a while now and can't figure out what to do.
Maybe someone can point me in the right direction.
I just want to pass in an argument into the get_or_create, so that I can conditionally perform a certain function in the save method.
When you do
kwargs = { "reindex": False}
ClassName.objects.get_or_create(**kwargs)
it is actually equivalent to
ClassName.objects.get_or_create(reindex=False)
Thus, since reindex appears not to be a field defined in the model ClassName, you get an error.
BTW, beyond things which appear erroneous, e.g. reindex = **kwargs.pop("reindex"), you should define reindex as one of the fields of your model. But I admit that I answer blindly, because to me, your class definition cannot work like so. If one assumes that reindex is an integer field, you could do
class ClassName(models.Model):
reindex = models.IntegerField(null=True)
def save(self, *args, **kwargs):
super(ClassName, self).save(*args, **kwargs)
if "reindex" in kwargs:
People.objects.create()
I have a model with a customized save() method that creates intermediate models if the conditions match:
class Person(models.Model):
integervalue = models.PositiveIntegerField(...)
some_field = models.CharField(...)
related_objects = models.ManyToManyField('OtherModel', through='IntermediaryModel')
...
def save(self, *args, **kwargs):
if self.pk is None: # if a new object is being created - then
super(Person, self).save(*args, **kwargs) # save instance first to obtain PK for later
if self.some_field == 'Foo':
for otherModelInstance in OtherModel.objects.all(): # creates instances of intermediate model objects for all OtherModels
new_Intermediary_Model_instance = IntermediaryModel.objects.create(person = self, other = otherModelInstance)
super(Person, self).save(*args, **kwargs) #should be called upon exiting the cycle
However, if editing an existing Person both through shell and through admin interface - if I alter integervalue of some existing Person - the changes are not saved. As if for some reason last super(...).save() is not called.
However, if I were to add else block to the outer if, like:
if self.pk is None:
...
else:
super(Person, self).save(*args, **kwargs)
the save() would work as expected for existing objects - changed integervalue is saved in database.
Am I missing something, or this the correct behavior? Is "self.pk is None" indeed a valid indicator that object is just being created in Django?
P.S. I am currently rewriting this into signals, though this behavior still puzzles me.
If your pk is None, super's save() is called twice, which I think is not you expect. Try these changes:
class Person(models.Model):
def save(self, *args, **kwargs):
is_created = True if not self.pk else False
super(Person, self).save(*args, **kwargs)
if is_created and self.some_field == 'Foo':
for otherModelInstance in OtherModel.objects.all():
new_Intermediary_Model_instance = IntermediaryModel.objects.create(person = self, other = otherModelInstance)
It's not such a good idea to override save() method. Django is doing a lot of stuff behind the scene to make sure that model objects are saved as they expected. If you do it in incorrectly it would yield bizarre behavior and hard to debug.
Please check django signals, it's convenient way to access your model object information and status. They provide useful parameters like instance, created and updated_fields to fit specially your need to check the object.
Thanks everyone for your answers - after careful examination I may safely conclude that I tripped over my own two feet.
After careful examination and even a trip with pdb, I found that the original code had mixed indentation - \t instead of \s{4} before the last super().save().
I am trying to add dynamically new form fields (I used this blog post), for a form used in admin interface :
class ServiceRoleAssignmentForm(forms.ModelForm):
class Meta:
model = ServiceRoleAssignment
def __init__(self, *args, **kwargs):
super(ServiceRoleAssignmentForm, self).__init__(*args, **kwargs)
self.fields['test'] = forms.CharField(label='test')
class ServiceRoleAssignmentAdmin(admin.ModelAdmin):
form = ServiceRoleAssignmentForm
admin.site.register(ServiceRoleAssignment, ServiceRoleAssignmentAdmin)
However, no matter what I try, the field doesn't appear on my admin form ! Could it be a problem related to the way admin works ? Or to ModelForm ?
Thank for any help !
Sébastien
PS : I am using django 1.3
When rendering your form in template, fields enumerating from fieldsets variable, not from fields. Sure you can redefine fieldsets in your AdminForm, but then validations will fail as original form class doesn't have such field. One workaround I can propose is to define this field in form definition statically and then redefine that field in form's init method dynamically. Here is an example:
class ServiceRoleAssignmentForm(forms.ModelForm):
test = forms.Field()
class Meta:
model = ServiceRoleAssignment
def __init__(self, *args, **kwargs):
super(ServiceRoleAssignmentForm, self).__init__(*args, **kwargs)
# Here we will redefine our test field.
self.fields['test'] = forms.CharField(label='test2')
I actually have a the same issue which I'm working through at the moment.
While not ideal, I have found a temporary workaround that works for my use case. It might be of use to you?
In my case I have a static name for the field, so I just declared it in my ModelForm. as normal, I then override the init() as normal to override some options.
ie:
def statemachine_form(for_model=None):
"""
Factory function to create a special case form
"""
class _StateMachineBaseModelForm(forms.ModelForm):
_sm_action = forms.ChoiceField(choices=[], label="Take Action")
class Meta:
model = for_model
def __init__(self, *args, **kwargs):
super(_StateMachineBaseModelForm, self).__init__(*args, **kwargs)
actions = (('', '-----------'),)
for action in self.instance.sm_state_actions():
actions += ((action, action),)
self.fields['_sm_action'] = forms.ChoiceField(choices=actions,
label="Take Action")
if for_model: return _StateMachineBaseModelForm
class ContentItemAdmin(admin.ModelAdmin):
form = statemachine_form(for_model=ContentItem)
Now as I mentioned before, this is not entirely 'dynamic', but this will do for me for the time being.
I have the exact same problem that, if I add the field dynamically, without declaring it first, then it doesn't actually exist. I think this does in fact have something to do with the way that ModelForm creates the fields.
I'm hoping someone else can give us some more info.
Django - Overriding get_form to customize admin forms based on request
Try to add the field before calling the super.init:
def __init__(self, *args, **kwargs):
self.fields['test'] = forms.CharField(label='test')
super(ServiceRoleAssignmentForm, self).__init__(*args, **kwargs)