i have one silly problem with Django M2M saving.
I don't use Django Admin (use my own custom templates)
So, I have simple relationship:
# models
class News(models.Model):
title = models.CharField(max_length=256)
class Webmaster(AbstractUser):
...
news = models.ManyToManyField(News)
I need after saving every news mark it as new to every webmaster. So i figure out something like this:
# models
class News(models.Model):
title = models.CharField(max_length=256)
def save(self, *args, **kwargs):
if self.id:
news = News.objects.all()[0]
self.webmasters.add(news)
super(News, self).save(*args, **kwargs)
But i try like 6-7 different ways, and my code still don't work, can you help? Thanks!
You have to use post_save () signal, add this code in models.py
def Webmaster_add(sender, instance, **kwargs):
#you can put here some condition stuff
w = Webmasters.objects.all()
for obj in w:
obj.news.add(instance)
# register the signal
post_save.connect(webmaster_add, sender=News)
Related
I am working on a project which is administered by a super admin who puts in data for different companies.
Lets say, I have these models:
class Company(models.Model):
name = models.CharField(max_length=100)
class ContactPerson(models.Model):
name = models.CharField(max_length=100)
company = models.ForeignKey(Company)
class Item(models.Model):
company = models.ForeignKey(Company)
contact_person = models.ForeignKey(ContactPerson)
I need to ensure that I (in django admin) in the edit mode I only see contact persons which belong to the selected company.
Being not in the year 2005 anymore I want to avoid writing loads of super ugly jQuery code.
I guess I could overwrite the admin form for Item. But still I had to make the contact_person optional, so when I create a new Item, the list of contact persons need to be empty. Then I'd select a company, save it and go back to edit. Now the contact_person list would be filled and I could add somebody. But if I now change the comany, I'd have to remove all selected contact persons. Sure, I could to this in the form... but it looks SO hacky and not like a nice django solution.
Anybody got some fancy ideas?
Actually, django provided me with a neat solution.
When you look at the UserAdmin class within the django code, you'll find a built-in way to handle a two-step creation process.
#admin.register(User)
class UserAdmin(admin.ModelAdmin):
...
add_form = UserCreationForm
...
def get_form(self, request, obj=None, **kwargs):
"""
Use special form during user creation
"""
defaults = {}
if obj is None:
defaults['form'] = self.add_form
defaults.update(kwargs)
return super().get_form(request, obj, **defaults)
When the attribute add_form is set and the object has no id yet (= we are creating it), it takes a different form than usual.
I wrapped this idea in an admin mixin like this:
class AdminCreateFormMixin:
"""
Mixin to easily use a different form for the create case (in comparison to "edit") in the django admin
Logic copied from `django.contrib.auth.admin.UserAdmin`
"""
add_form = None
def get_form(self, request, obj=None, **kwargs):
defaults = {}
if obj is None:
defaults['form'] = self.add_form
defaults.update(kwargs)
return super().get_form(request, obj, **defaults)
Now, when I have dependent fields, I create a small form, containing all values independent of - in my case - company and a regular form containing everything.
#admin.register(Item)
class ItemAdmin(AdminCreateFormMixin, admin.ModelAdmin):
form = ItemEditForm
add_form = ItemAddForm
...
Now I can customise the querysets of the dependent field in my edit form:
class ItemEditForm(forms.ModelForm):
class Meta:
model = Item
exclude = ()
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['contact_person'].queryset = ContactPerson.objects.filter(company=self.instance.company)
The only drawback is, that all dependent fields need to be nullable for the database. Otherwise you wouldn't be able to save it in the creation process.
Luckily, you can tell django that a field is required in the form but not on database level with blank=False, null=True in the model declaration.
Hope this helps somebody else as well!
I have been searching for an answer for hours, however every answer I found does not work. Also trying to find a bug on my own didn't bring me any results.
I have created a receiver function which should update model's total_likes attribute(based on number of users_like attribute) every time user click on the like button of the specific image. (This is a part of 'Django by Example` book). But the field's value stays always the same and is equal to default value of 0. Even if I try to assign the value to the field manually, in the django's shell, it does not change(code example in 'Update' section).
Can someone please have a look at the code and point me in the right directions if I am doing something wrong?
I am using Django 1.9.
# models.py
class Image(models.Model):
...
users_like = models.ManyToManyField(settings.AUTH_USER_MODEL,
related_name='images_liked',
blank=True)
total_likes = models.PositiveIntegerField(default=5)
def save(self, *args, **kwargs):
if not self.slug:
self.slug = slugify(self.title)
super(Image, self).save(*args, **kwargs)
# signals.py
from django.db.models.signals import m2m_changed
from django.dispatch import receiver
from .models import Image
#receiver(m2m_changed, sender=Image.users_like.through)
def users_like_changed(sender, instance, **kwargs):
instance.total_likes = instance.users_like.count()
instance.save()
# apps.py
from django.apps import AppConfig
class ImagesConfig(AppConfig):
name = 'images'
verbose_name = 'Image bookmarks'
def ready(self):
# import signal handlers
import images.signals
# __init__.py
default_app_config = 'images.apps.ImagesConfig'
Update:
When I run code below from django shell, this does change the total_likes value, but it looks like it do just temporary:
from images.models import Image
for image in Image.objects.all():
print(image.total_likes)
image.total_likes = image.users_like.count()
print(image.total_likes)
image.save()
print(image.total_likes)
Output from code above:
0 #initial/default value of 0
3 #current number of users who like the picture
3
Because when I run the for loop code again, to see the results(or even check the field value in admin interface) i still get the initial/default value of 0.
Can someone see the problem why the field does not get updated?
Ok, so the problem was with the custom save() method on the model class.
I needed to call the save() method of the parent class like this:
def save(self, *args, **kwargs):
if not self.slug:
self.slug = slugify(self.title)
super(Image, self).save(*args, **kwargs)
and it made it work.
I have two apps in Django where one app's model (ScopeItem) on its instance creation must create an instance of the other app's model as well (Workflow); i.e. the ScopeItem contains it's workflow.
This works nicely when tried from the shell. Creating a new ScopeItem creates a Workflow and stores it in the ScopeItem. In admin I get an error, that the workflow attribute is required. The attribute is not filled in and the model definition requires it to be set. The overwritten save method though does this. Hence my question is, how to call save before the check in admin happens?
If I pick an existing Workflow instance in admin and save (successfully then), then I can see that my save method is called later and a new Workflow is created and attached to the ScopeItem instance. It is just called too late.
I am aware that I could allow empty workflow attributes in a ScopeItem or merge the ScopeItem and the Workflow class to avoid the issue with admin. Both would cause trouble later though and I like to avoid such hacks.
Also I do not want to duplicate code in save_item. Just calling save from there apparently does not cut it.
Here is the code from scopeitems/models.py:
class ScopeItem(models.Model):
title = models.CharField(max_length=64)
description = models.CharField(max_length=4000, null=True)
workflow = models.ForeignKey(Workflow)
def save(self, *args, **kwargs):
if not self.id:
workflow = Workflow(
description='ScopeItem %s workflow' % self.title,
status=Workflow.PENDING)
workflow.save()
self.workflow = workflow
super(ScopeItem, self).save(*args, **kwargs)
And workflow/models.py:
from django.utils.timezone import now
class Workflow(models.Model):
PENDING = 0
APPROVED = 1
CANCELLED = 2
STATUS_CHOICES = (
(PENDING, 'Pending'),
(APPROVED, 'Done'),
(CANCELLED, 'Cancelled'),
)
description = models.CharField(max_length=4000)
status = models.IntegerField(choices=STATUS_CHOICES)
approval_date = models.DateTimeField('date approved', null=True)
creation_date = models.DateTimeField('date created')
update_date = models.DateTimeField('date updated')
def save(self, *args, **kwargs):
if not self.id:
self.creation_date = now()
self.update_date = now()
super(Workflow, self).save(*args, **kwargs)
In scopeitems/admin.py I have:
from django.contrib import admin
from .models import ScopeItem
from workflow.models import Workflow
class ScopeItemAdmin(admin.ModelAdmin):
list_display = ('title', 'description', 'status')
list_filter = ('workflow__status', )
search_fields = ['title', 'description']
def save_model(self, request, obj, form, change):
obj.save()
def status(self, obj):
return Workflow.STATUS_CHOICES[obj.workflow.status][1]
admin.site.register(ScopeItem, ScopeItemAdmin)
You could set the field blank=True on workflow.
You said you don't want to allow "empty workflow attributes in a ScopeItem." Setting blank=True is purely validation-related. Thus, on the backend workflow will still be NOT NULL. From the Django docs:
If a field has blank=True, form validation will allow entry of an empty value.
Referring to your example you should be able to use:
workflow = models.ForeignKey(Workflow, blank=True)
You need to exclude the field from the form used in the admin, so that it won't be validated.
class ScopeItemForm(forms.ModelForm):
class Meta:
exclude = ('workflow',)
model = ScopeItem
class ScopeItemAdmin(admin.ModelAdmin):
form = ScopeItemForm
...
admin.site.register(ScopeItem, ScopeItemAdmin)
#Daniel Roseman's answer is correct as long as you don't need to edit the workflow field in admin at any time. If you do need to edit it then you'll need to write a custom clean() method on the admin form.
forms.py
class ScopeItemAdminForm(forms.ModelForm):
class Meta:
model = ScopeItem
def clean(self):
cleaned_data = super(ScopeItemAdminForm, self).clean()
if 'pk' not in self.instance:
workflow = Workflow(
description='ScopeItem %s workflow' % self.title,
status=Workflow.PENDING)
workflow.save()
self.workflow = workflow
return cleaned_data
admin.py
class ScopeItemAdmin(admin.ModelAdmin):
form = ScopeItemAdminForm
...
admin.site.register(ScopeItem, ScopeItemAdmin)
Answering my own question:
As #pcoronel suggested, the workflow attribute in ScopeItem must have blank=True set to get out of the form in the first place.
Overwriting the form's clean method as suggested by #hellsgate was also needed to create and store the new Workflow.
To prevent code duplication I added a function to workflow/models.py:
def create_workflow(title="N/A"):
workflow = Workflow(
description='ScopeItem %s workflow' % title,
status=Workflow.PENDING)
workflow.save()
return workflow
This makes the ScopeItemAdminForm look like this:
class ScopeItemAdminForm(forms.ModelForm):
class Meta:
model = ScopeItem
def clean(self):
cleaned_data = super(ScopeItemAdminForm, self).clean()
cleaned_data['workflow'] = create_workflow(cleaned_data['title'])
return cleaned_data
Additionally I changed the save method in scopeitems/models.py to:
def save(self, *args, **kwargs):
if not self.id:
if not self.workflow:
self.workflow = create_workflow(self.title)
super(ScopeItem, self).save(*args, **kwargs)
I'm making a Django app with custom users. I've outlined the key components of my problem below, missing code is denoted by '...'. My custom user model has a foreign key relationship as follows:
class MyCustomUser(models.AbstractBaseUser, models.PermissionsMixin)
...
location = models.ForeignKey(Location)
class Location(models.Model)
name = models.CharField(max_length=50, blank=True, null=True)
I've written a custom user form that includes this field as follows:
class MyCustomUserCreationForm(models.ModelForm)
...
location = forms.ModelChoiceField(Location.objects.all())
This all appears to be working correctly, however, there is no plus button to the right of the select field for location. I want to be able to add a location when I create a user, in the same way that you can add polls when creating choices in the Django tutorial. According to this question, I might not see the green plus if I don't have permission to change the model, but I am logged in as a superuser with all permissions. Any idea what I'm doing wrong?
You need to set a RelatedFieldWidgetWrapper wrapper in your model form:
The RelatedFieldWidgetWrapper (found in django.contrib.admin.widgets)
is used in the Admin pages to include the capability on a Foreign Key
control to add a new related record. (In English: puts the little green plus sign to the right of the control.)
class MyCustomUserCreationForm(models.ModelForm)
...
location = forms.ModelChoiceField(queryset=Location.objects.all())
def __init__(self, *args, **kwargs):
super(MyCustomUserCreationForm, self).__init__(*args, **kwargs)
rel = ManyToOneRel(self.instance.location.model, 'id')
self.fields['location'].widget = RelatedFieldWidgetWrapper(self.fields['location'].widget, rel, self.admin_site)
I could make a mistake in the example code, so see these posts and examples:
RelatedFieldWidgetWrapper
More RelatedFieldWidgetWrapper – My Very Own Popup
Django admin - How can I add the green plus sign for Many-to-many Field in custom admin form
How can I manually use RelatedFieldWidgetWrapper around a custom widget?
Django: override RelatedFieldWidgetWrapper
I have created method based on the answers above:
def add_related_field_wrapper(form, col_name):
rel_model = form.Meta.model
rel = rel_model._meta.get_field(col_name).rel
form.fields[col_name].widget =
RelatedFieldWidgetWrapper(form.fields[col_name].widget, rel,
admin.site, can_add_related=True, can_change_related=True)
And then calling this method from my form:
class FeatureForm(forms.ModelForm):
offer = forms.ModelChoiceField(queryset=Offer.objects.all(), required=False)
package = forms.ModelChoiceField(queryset=Package.objects.all(), required=False)
def __init__(self, *args, **kwargs):
super(FeatureForm, self).__init__(*args, **kwargs)
add_related_field_wrapper(self, 'offer')
add_related_field_wrapper(self, 'package')
That works fine on Django 1.8.2.
Google pointed me to this page when searching how to get a "+" icon next to fields in a custom form with ForeignKey relationship, so I thought I'd add.
For me, using django-autocomplete-light did the trick very well, using the "add another" functionality.
You don't even need to go that far, and besides, these answers are probably outdated as NONE of them worked for me in any capacity.
What I did to solve this is, as long as you have the ForeignKey field already in your model, then you can just create your custom ModelChoiceField:
class LocationModelChoiceField(forms.ModelChoiceField):
def label_from_instance(self, obj):
return "%" % (obj.name)
The key next is NOT to create a custom field for the ModelChoiceField in your ModelForm (ie location = forms.ModelChoiceField(Location.objects.all()))
In other words, leave that out and in your ModelForm have something like this:
class UserAdminForm(forms.ModelForm):
class Meta:
model = User
fields = '__all__'
Lastly, in your ModelAdmin:
class UserAdmin(admin.ModelAdmin):
model = User
form = UserAdminForm
def formfield_for_foreignkey(self, db_field, request, **kwargs):
if db_field.name == 'location':
return LocationModelChoiceField(queryset=Location.objects.order_by('name')) # if you want to alphabetize your query
return super().formfield_for_foreignkey(db_field, request, **kwargs)
Alternative Method : Using .remote_field instead of rel
def add_related_field_wrapper(self,form, col_name):
rel_model = form.Meta.model
rel = rel_model._meta.get_field(col_name).remote_field
form.fields[col_name].widget = RelatedFieldWidgetWrapper(form.fields[col_name].widget, rel, admin.site, can_add_related=True, can_change_related=True)
def __init__(self, *args, **kwargs):
super(CustomerAdminForm, self).__init__(*args, **kwargs)
self.add_related_field_wrapper(self, 'offer')
self.add_related_field_wrapper(self, 'package')
Thankyou,
I'm going to use 'prepopulated_fields' at Django admin to get a YouTube embed code from its video id, as below.
class VideoAdmin(admin.ModelAdmin):
prepopulated_fields = {"embed_code": ("embed_id",)}
inlines = (CourseVideoInline,)
but embed_code I can get from "Rmp6zIr5y4U" is "rmp6zir5y4u", all capital letters changed into small ones.
Have any ideas to solve this?or is any better ways to get embed code from video id by customizing Django admin?
Thanks!
Video model (related fields) is below.
class Video(models.Model):
embed_code = models.TextField(max_length=1000)
embed_id = models.CharField(max_length=200)
prepopulated_fields are mainly used for generating slugs from titles via javascript - hence why you see it in lowercase. You might be better off overwriting the models save function so that when an instance of your model is saved, it can grab the video_id and generate the embed_code:
class MyModel(models.Model):
video_id = ...
embed_code = ...
def save(self, *args, **kwargs):
# If we have enetered a video id, but there is not saved embed code, generate it
if not self.embed_code and self.video_id:
self.embed_code = "http://youtube.com/%s" % self.video_id
super(MyModel, self).save(*args, **kwargs)
an alternative is to do this at the admin view level (as opposed to the model level). You could do this by overwriting the save_model method of the ModelAdmin class. This gives you the added bonus of having access to the request and the form:
class MyModelAdmin(admin.ModelAdmin):
def save_model(self, request, obj, form, change):
video_id = forms.cleaned_data.get('video_id', None)
# If we are creating the object, and the video id is present
if video_id and not change:
obj.embed_code = video_id
obj.save()
This code is untested, it's just to illustrate the two places you might want to achieve what you are looking to do