I have a class like so:
class EmailForm(forms.Form):
users = forms.MultipleChoiceField(required=False, widget=MultipleHiddenInput())
subject = forms.CharField(max_length=100)
message = forms.Textarea()
def __init__(self, users, *args, **kwargs):
super(EmailForm, self).__init__(*args, **kwargs)
self.users.choices = users
# self.fields['users'].choices = []
The commented line at the bottom works perfectly if I use it instead of self.users.
Am I right in thinking that users, subject and message are class level so that is why they are popped out of the attribute list?
So self.fields is the per object copy of the attributes in case I want to change them in some way?
Thanks.
The Form class uses the DeclarativeFieldsMetaclass, which enables the declarative syntax for the fields.
The implementation means that the form class and instance does not actually have an attribute self.field_name for each field. That is why trying to use self.users gives an error.
The fields of the form instance can be accessed as self.fields, which is created when you call super in the __init__ method.
The fields of the form class can be accessed as self.base_fields.
Related
I got the two following models:
class Stuff(models.Model):
...
def custom_function(self):
...
class MyModel(models.Model):
name = models.CharField(max_length=200)
many_stuff = models.ManyToManyField(Stuff, related_name="many_stuff+")
many_other_stuff = models.ManyToManyField(Stuff, related_name="many_other_stuff+")
def __init__(self, *args, **kwargs):
super(MyModel, self).__init__(*args, **kwargs)
for stuff in self.many_stuff.all():
many_stuff.custom_function()
def on_save(self, *args, **kwargs):
for stuff in self.many_stuff.all():
many_stuff.custom_function()
super(MyModel, self).save(*args, **kwargs)
When I create a new instance of MyModel through the Django Admin, I want to execute for each Stuff object, a function. It works on_save but I cannot make it work on __init__ for some reason. If I create the new instance, the functions don't get executed. If I save the newly created instance, the functions do get executed.
To be more specific, when I use this __init__ method, the model breaks on instance creation with the error:
MyModel needs to have a value for field "id" before this many-to-many relationship can be used.
I also attempted doing the same thing with the post_save signal, instead of using __init__ and on_save but I had the same problem. On object creation, the function custom_function did not get executed, but it did when I saved the object after it has been created by clicking on the save button.
Any ideas?
You simply cant create M2M join while creating object.
Because M2M model fields don't have real db fields, but have intermediary table that stores id from both model. When you create relation between two objects, both objects must have an id value ready to use.
First create MyModel instance without M2M fields, than set M2M fields. Something like that;
newModel = MyModel.objects.create(name=someting)
newStuff = Stuff.objects.create(..)
newModel.many_stuff.add(newStuff)
I'm using django-tables2 and trying to create a new DeleteColumn class:
tables.py
class DeleteColumn(tables.TemplateColumn):
def __init__(self, *args, **kwargs):
super(DeleteColumn, self).__init__(*args, **kwargs)
self.template_name='wakemeup/admin/delete_link.html'
self.verbose_name=''
class SchoolsTable(tables.Table):
test = DeleteColumn()
class Meta:
model = School
I keep getting this error, though: ValueError: A template must be provided
Am I not creating the class properly? Why doesn't the template_name value specified in the class get passed along when creating a new instance of DeleteColumn?
Can someone please point me in the right direction?
If you take a look at the source of TemplateColumn (http://django-tables2.readthedocs.io/en/latest/_modules/django_tables2/columns/templatecolumn.html) you'll see that __init__() checks for a template_column or template_name attribute and if neither is found the ValueError you mention is thrown.
Now the problem is that you set the template_name attribute after you have called super(...).__init__ in your class, thus the template_name attribute is empty!
Edited
Sorry I didn't check the source code very thouroughly, it's been written in a funny way and doesn't use the attributes. In any case, from what I see now, you'll need to override __init__ to pass the template_name parameter to the parent's init, something like this:
class DeleteColumn(tables.TemplateColumn):
def __init__(self, *args, **kwargs):
# This will pass ``template_name`` to the super().__init__ along with any args and kwargs
super(DeleteColumn, self).__init__(*args, template_name='wakemeup/admin/delete_link.html', **kwargs)
self.verbose_name=''
I hope it works now!
I'm trying to write use Django FormView and a bit of ingenuity to create a view which will allow me to get inputs from a user that will be fed to a function. I'd like the code to be reusable, so I'd like to make a view that will be able to take a target function as a parameter and automagically create a form appropriate to that function. There is more plumbing to be done, but the general idea would be:
class FormViewForFunction(FormView):
template_name = '...'
func = None
def get_form_class(self):
class _FunctionForm(forms.Form):
pass
a = inspect.getargspec(self.func)
for argname in a['args']:
setattr(_FunctionForm, argname, forms.CharField())
return _FunctionForm
The idea would be that then you could set up something in your URLConf that used FormViewForFunction.as_view(func=***insert any function you want***) and you would wind up being presented with a form that was appropriate for specifying parameters for that function. Let's not worry about what would happen on form submission. For now I'm just stuck getting the form to generate properly.
With the code above, the form doesn't wind up having any fields! What am I doing wrong?
form's fields are initialized during initialization, you should override the __init__ method and then append the fields to the self.fields dictionary
This should work:
class FormViewForFunction(FormView):
template_name = '...'
func = None
def get_form_class(self):
a = inspect.getargspec(self.func)
class _FunctionForm(forms.Form):
def __init__(self, *args, **kwargs):
super(_FunctionForm, self).__init__(*args, **kwargs)
for argname in a['args']:
self.fields[argname] = forms.CharField()
return _FunctionForm
I have a filter where I need to access the request.user. However, django-filter does not pass it. Without using the messy inspect.stack() is there a way to get the current user in the method member_filter below?
class ClubFilter(django_filters.FilterSet):
member = django_filters.MethodFilter(action='member_filter')
class Meta:
model = Club
fields = ['member']
def member_filter(self, queryset, value):
# get current user here so I can filter on it.
return queryset.filter(user=???)
For example this works but feels wrong...
def member_filter(self, queryset, value):
import inspect
request_user = None
for frame_record in inspect.stack():
if frame_record[3] == 'get_response':
request_user = frame_record[0].f_locals['request'].user
print(request_user)
is there maybe a way to add this to some middleware that injects user into all methods? Or is there a better way?
Yes, you can do it, and it's very easy.
First, define __init__ method in your ClubFilter class that will take one extra argument:
class ClubFilter(django_filters.FilterSet):
# ...
def __init__(self, *args, **kwargs):
self.user = kwargs.pop('user')
super(ClubFilter, self).__init__(*args, **kwargs)
With having your user saved into attribute inside ClubFilter, you can use it in your filter. Just remember to pass current user from your view inside FilterSet.
Try self.request.user.
Why it must work.
you can access the request instance in FilterSet.qs property, and then filter the primary queryset there.
class ClubFilter(django_filters.FilterSet):
member = django_filters.MethodFilter(action='member_filter')
class Meta:
model = Club
fields = ['member']
#property
def qs(self):
primary_queryset=super(ClubFilter, self).qs
return primary_queryset.filter(user=request.user)
I'm experimenting with django-nonrel on appengine and trying to use a djangotoolbox.fields.ListField to implement a many-to-many relation. As I read in the documentation a ListField is something that you can use to make a workaround for djamgo-nonrel not supporting many-to-many relations.
This is an excerpt from my model:
class MyClass(models.Model):
field = ListField(models.ForeignKey(AnotherClass))
So if I am getting this right I am creating a list of foreign keys to another class to show a relationship with multiple instances of another class
With this approach everything works fine ... No Exceptions. I can create `MyClass' objects in code and views. But when I try to use the admin interface I get the following error
No form field implemented for <class 'djangotoolbox.fields.ListField'>
So I though I would try something that I haven't done before. Create my own field. Well actually my own form for editing MyClass instances in the admin interface. Here is what I did:
class MyClassForm(ModelForm):
field = fields.MultipleChoiceField(choices=AnotherClass.objects.all(), widget=FilteredSelectMultiple("verbose_name", is_stacked=False))
class Meta:
model = MyClass
then I pass MyClassForm as the form to use to the admin interface
class MyClassAdmin(admin.ModelAdmin):
form = MyClassForm
admin.site.register(MyClass, MyClassAdmin)
I though that this would work but It doesn't. When I go to the admin interface I get the same error as before. Can anyone tell what I am doing wrong here ... or if you have any other suggestions or success stories of using the ListField, SetField, etc. from djangotoolbox.fields in the admin interface it would be very much appreciated.
OK, here is what I did to get this all working ...
I'll start from the beginning
This is what what my model looked like
class MyClass(models.Model):
field = ListField(models.ForeignKey(AnotherClass))
I wanted to be able to use the admin interface to create/edit instances of this model using a multiple select widget for the list field. Therefore, I created some custom classes as follows
class ModelListField(ListField):
def formfield(self, **kwargs):
return FormListField(**kwargs)
class ListFieldWidget(SelectMultiple):
pass
class FormListField(MultipleChoiceField):
"""
This is a custom form field that can display a ModelListField as a Multiple Select GUI element.
"""
widget = ListFieldWidget
def clean(self, value):
#TODO: clean your data in whatever way is correct in your case and return cleaned data instead of just the value
return value
These classes allow the listfield to be used in the admin. Then I created a form to use in the admin site
class MyClassForm(ModelForm):
def __init__(self, *args, **kwargs):
super(MyClasstForm,self).__init__(*args, **kwargs)
self.fields['field'].widget.choices = [(i.pk, i) for i in AnotherClass.objects.all()]
if self.instance.pk:
self.fields['field'].initial = self.instance.field
class Meta:
model = MyClass
After having done this I created a admin model and registered it with the admin site
class MyClassAdmin(admin.ModelAdmin):
form = MyClassForm
def __init__(self, model, admin_site):
super(MyClassAdmin,self).__init__(model, admin_site)
admin.site.register(MyClass, MyClassAdmin)
This is now working in my code. Keep in mind that this approach might not at all be well suited for google_appengine as I am not very adept at how it works and it might create inefficient queries an such.
As far as I understand, you're trying to have a M2M relationship in django-nonrel, which is not an out-of-the-box functionality. For starters, if you want a quick hack, you can go with this simple class and use a CharField to enter foreign keys manually:
class ListFormField(forms.Field):
""" A form field for being able to display a djangotoolbox.fields.ListField. """
widget = ListWidget
def clean(self, value):
return [v.strip() for v in value.split(',') if len(v.strip()) > 0]
But if you want to have a multiple selection from a list of models normally you'd have to use ModelMultipleChoiceField, which is also not functional in django-nonrel. Here's what I've done to emulate a M2M relationship using a MultipleSelectField:
Let's say you have a M2M relationship between 2 classes, SomeClass and AnotherClass respectively. You want to select the relationship on the form for SomeClass. Also I assume you want to hold the references as a ListField in SomeClass. (Naturally you want to create M2M relationships as they're explained here, to prevent exploding indexes if you're working on App Engine).
So you have your models like:
class SomeClass(models.Model):
another_class_ids = ListField(models.PositiveIntegerField(), null=True, blank=True)
#fields go here
class AnotherClass(models.Model):
#fields go here
And in your form:
class SomeClassForm(forms.ModelForm):
#Empty field, will be populated after form is initialized
#Otherwise selection list is not refreshed after new entities are created.
another_class = forms.MultipleChoiceField(required=False)
def __init__(self, *args, **kwargs):
super(SomeClassForm,self).__init__(*args, **kwargs)
self.fields['another_class'].choices = [(item.pk,item) for item in AnotherClass.objects.all()]
if self.instance.pk: #If class is saved, highlight the instances that are related
self.fields['another_class'].initial = self.instance.another_class_ids
def save(self, *args, **kwargs):
self.instance.another_class_ids = self.cleaned_data['another_class']
return super(SomeClassForm, self).save()
class Meta:
model = SomeClass
Hopefully this should get you going for the start, I implemented this functionality for normal forms, adjust it for admin panel shouldn't be that hard.
This could be unrelated but for the admin interface, be sure you have djangotoolbox listed after django.contrib.admin in the settings.. INSTALLED_APPS
You could avoid a custom form class for such usage by inquiring for the model object
class ModelListField(ListField):
def __init__(self, embedded_model=None, *args, **kwargs):
super(ModelListField, self).__init__(*args, **kwargs)
self._model = embedded_model.embedded_model
def formfield(self, **kwargs):
return FormListField(model=self._model, **kwargs)
class ListFieldWidget(SelectMultiple):
pass
class FormListField(MultipleChoiceField):
widget = ListFieldWidget
def __init__(self, model=None, *args, **kwargs):
self._model = model
super(FormListField, self).__init__(*args, **kwargs)
self.widget.choices = [(unicode(i.pk), i) for i in self._model.objects.all()]
def to_python(self, value):
return [self._model.objects.get(pk=key) for key in value]
def clean(self, value):
return value