I have Django database with 2 models: DeviceModel and Device. Let's say, for example, DeviceModel object is "LCD panel" and Device object is "LCD panel №547". So these two tables have ManyToOne relationship.
class DeviceModel(models.Model):
name = models.CharField(max_length=255)
class Device(models.Model):
device_model = models.ForeignKey(DeviceModel)
serial_number = models.CharField(max_length=255)
Now I need to add some relations between DeviceModel objects. For example "LCD Panel" can be in "Tablet" object or in "Monitor" object. Also another object can be individual, so it doesn't link with other objects.
I decided to do this with ManyToMany relationship, opposed to using serialization with JSON or something like that (btw, which approach is better in what situation??).
I filled all relationships between device models and know I need to add relationship functional to Device table.
For that purpose I added "master_dev" foreignkey field pointing to 'self'. It works exactly as I need, but I want to restrict output in django admin panel. It should display only devices, that are connected through device_links. Current code:
class DeviceModel(models.Model):
name = models.CharField(max_length=255)
device_links = models.ManyToManyField('self')
class Device(models.Model):
device_model = models.ForeignKey(DeviceModel)
serial_number = models.CharField(max_length=255)
master_dev = models.ForeignKey('self', blank=True, null=True)
So, how can I limit output of master_dev field in admin panel?
There is a function "limit_choices_to", but I can't get it to work...
in forms.py:
def master_dev_chioses():
chioses = DeviceModel.objects.filter(do your connection filter here - so not all Devicemodels comes to choicefield)
class DeviceForm(forms.ModelForm):
class Meta:
model = Device
def __init__(self, *args, **kwargs):
super(Device, self).__init__(*args, **kwargs)
self.fields['master_dev'].choices = master_dev_chioses()
While there is no direct answer to my question about "limit_choices_to" function, I post solution that achieves desired output:
from django import forms
from django.contrib import admin
from .models import DeviceModel, Device
class DeviceForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(DeviceForm, self).__init__(*args, **kwargs)
try:
linked_device_models = self.instance.device_model.device_links.all()
linked_devices = Device.objects.filter(device_model__in=linked_device_models)
required_ids = set(linked_devices.values_list("id", flat=True))
self.fields['master_dev'].queryset = Device.objects.filter(id__in=required_ids).order_by("device_model__name", "serial_number")
except:
# can't restrict masters output if we don't know device yet
# admin should edit master_dev field only after creation
self.fields['master_dev'].queryset = Device.objects.none()
class Meta:
model = Device
fields = ["device_model", "serial_number", "master_dev"]
class DeviceAdmin(admin.ModelAdmin):
form = DeviceForm
list_display = ('id', 'device_model', 'serial_number')
list_display_links = ('id', 'device_model')
search_fields = ('device_model__name', 'serial_number')
list_per_page = 50
list_filter = ('device_model',)
Related
I have an example model which has a fk relation with user model and Blog model. Now I have a get api which only requires certain fields of user to be displayed.
My model:
class Example(models.Model):
user = models.ForeignKey(
settings.AUTH_USER_MODEL,
on_delete=models.CASCADE,
null=True,
related_name="user_examples",
)
blog = models.ForeignKey(
Blog,
on_delete=models.CASCADE,
null=True,
related_name="blog_examples",
)
/................./
Now my view:
class ExampleView(viewsets.ModelViewSet):
queryset = Example.objects.all()
serializer_class = ExampleSerializer
def list(self, request, *args, **kwargs):
id = self.kwargs.get('pk')
queryset = Example.objects.filter(blog=id)
serializer = self.serializer_class(queryset,many=True)
return Response(serializer.data,status=200)
My serializer:
class ExampleSerializer(serializers.ModelSerializer):
class Meta:
model = Example
fields = ['user','blog','status']
depth = 1
Now when I call with this get api, I get all example objects that is required but all the unnecessary fields of user like password, group etc . What I want is only user's email and full name. Same goes with blog, I only want certain fields not all of them. Now how to achieve this in a best way??
You will have to specify the required fields in nested serializers. e.g.
class BlogSerializer(serializers.ModelSerializer):
class Meta:
model = Blog
fields = ['title', 'author']
class ExampleSerializer(serializers.ModelSerializer):
blog = BlogSerializer()
class Meta:
model = Example
fields = ['user','blog','status']
are you setting depth in serializer's init method or anywhere else? beacause ideally it should only display id's and not anything else. if yes then set depth to zero and use serializer's method field to return data that you need on frontend. I can provide you with example code samples
I'm trying to build a filter that corresponds to the has_images method on my Django admin, but I can't because it strictly says that has_images is not a field of the model. I tried setting it up as a property, but it also didn't work.
I thought about defining has_images as a field and really calculating it, based on the changes on the model, but I think that would be not optimal.
What would be a good solution here?
models.py
class Product(models.Model):
name = models.CharField("Name", max_length=255)
def has_images(self):
return self.images.all().count() > 0
has_images.boolean = True
class ProductImage(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name="images")
file = models.ImageField("Product Image")
admin.py
class ProductImageInline(admin.TabularInline):
model = ProductImage
fields = ('file',)
extra = 1
class ProductAdmin(VersionAdmin):
list_display = ('id', 'name', 'has_images',)
inlines = (ProductImageInline,)
Expected result:
Can you share the contents of the admin.py file?
Or let me explain it as follows. Add a feature called list_filter = ('images') into the ProductAdmin class you created in admin.py. If this feature doesn't work (I'm not sure as I haven't tried it), if you create an Admin Class for ProductImages directly, you can already view the pictures and the corresponding Product on that page.
----------- EDIT ----------------
This is how I solved the problem.
models.py
from django.db import models
class Product(models.Model):
name = models.CharField("Name", max_length=255)
is_image = models.BooleanField(default=False, editable=False)
def save(self, *args, **kwargs):
if self.images.count():
self.is_image = True
else:
self.is_image = False
super(Product, self).save(*args, **kwargs)
class ProductImage(models.Model):
product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name="images")
file = models.ImageField("Product Image")
def save(self, *args, **kwargs):
super(ProductImage, self).save(*args,**kwargs)
self.product.save()
admin.py
from django.contrib import admin
from .models import *
class ProductImageInline(admin.TabularInline):
model = ProductImage
fields = ('file',)
extra = 1
class ProductAdmin(admin.ModelAdmin):
list_display = ('id', 'name',)
list_filter = ('is_image',)
inlines = (ProductImageInline,)
admin.site.register(Product, ProductAdmin)
Here I added an is_image BooleanField field with False by default. Every time the save method of the Product model runs, it checks whether there is an image in the ProductImage to which the Product model is attached. If there is an image in it, is_image is set as True.
I have the (simple, I suppose) need of having a situation like so: there are many profiles, and there are many ensembles, and each profile has to be able to be part of one or more ensembles. This is my code:
class Ensemble(models.Model):
ensembleName = models.CharField(max_length=200)
members = models.ManyToManyField('Profile', related_name='members')
def __str__(self):
return self.ensembleName
class Profile(models.Model):
ensemble = models.ForeignKey(Ensemble, on_delete=models.CASCADE, blank=True, null=True)
[...]
It all works well, but to an extent. From the Django administration I can, from the 'ensemble' page, select its members. I can also select, from the 'profile' page, which ensembles that profile belongs. The issue is: they are not synchronised: if I add a profile to an ensemble via the 'profile' page this is not reflected in the 'ensemble' page and the other way round, i.e. in the 'profiles details' page I don't see the ensemble to which I previously assigned that profile from the 'ensemble' page.
My form
class ProfileUpdateForm(forms.ModelForm):
class Meta:
model = Profile
fields = ('image', 'role', 'skills', 'gender', etc...)
class EnsemblesForm(forms.ModelForm):
class Meta:
model = Ensemble
fields = ('ensemble_name',)
def __init__(self, *args, **kwargs):
super(EnsemblesForm, self).__init__(*args, **kwargs)
self.fields['ensemble_name'].queryset = (obj for obj in Ensemble.objects.all()) #This doesn't output anything
I have an Event object in my postgres db, and created a new Collection object to group events by theme via a ManyToMany field relationship:
class Collection(models.Model):
event = models.ManyToManyField('Event', related_name='collections')
name = models.CharField(blank=True, max_length=280)
slug = AutoSlugField(populate_from='name')
image = models.ImageField(upload_to='collection_images/', blank=True)
description = models.TextField(blank=True, max_length=1000)
theme = models.ManyToManyField('common.Tag', related_name='themes')
date_created = models.DateTimeField(auto_now_add=True)
date_updated = models.DateTimeField(auto_now=True)
is_active = models.BooleanField(default=False)
def __str__(self):
return self.name
def get_absolute_url(self):
return reverse('collection', args=[self.slug])
def clean(self):
# because of the way db saves M2M relations, collection doesn't have a
# type at this time yet, so image inheritance is
# called from the signal which is triggered when M2M is created
# (that means if an image is later deleted, it won't inherit a new
# one when collection is saved)
if self.image:
validate_hero_image(self.image, 'image')
def save(self, *args, **kwargs):
try:
self.full_clean()
except ValidationError as e:
log.error('Collection validation error (name = %s): %s' % (self.name, e))
return super(Collection, self).save(*args, **kwargs)
in my admin, I'm defining and registering CollectionAdmin like this:
class CollectionAdmin(admin.ModelAdmin):
model = Collection
verbose_name = 'Collection'
list_display = ( 'name', )
however, if I go into admin and attempt to create a Collection "GET /admin/app/collection/add/" 200, the request frequently times out and the query load on my database from the Event M2M relationship seems quite heavy from logging. For reference currently the db has ~100,000 events. are there better ways to (re)structure my admin fields so I can select specific events (by name or id) to add to a Collection without effectively requesting a QuerySet of all events when that view is loaded (or creating them in db via shell)? thanks
There are multiple ways to accomplish this. For example, you could override the form fields the admin uses and specify another widget to use, like NumberInput.
You could also add your event model field to the raw_id_fields attribute of ModelAdmin. By doing so, Django won't try to create a fully populated select input but will offer you a way to search for events manually if needed:
class CollectionAdmin(admin.ModelAdmin):
model = Collection
verbose_name = 'Collection'
list_display = ('name', )
raw_id_fields = ('event', )
I've implemented a circular OneToMany relationship at a Django model and tried to use the limit_choices_to option at this very same class.
I can syncdb without any error or warning but the limit is not being respected.
Using shell I'm able to save and at admin I receive the error message:
"Join on field 'type' not permitted.
Did you misspell 'neq' for the lookup
type?"
class AdministrativeArea(models.Model):
type = models.CharField(max_length=1, choices=choices.ADMIN_AREA_TYPES)
name = models.CharField(max_length=60, unique=True)
parent = models.ForeignKey('AdministrativeArea',
null=True,
blank=True,
limit_choices_to = Q(type__neq='p') & Q(type__neq=type)
)
The basic idea for the limit_choices_to option is to guarantee that any type "p" cannot be parent ofr any other AdministrativeArea AND the parent cannot be of the same type as the current AdministrativeArea type.
I'm pretty new to Django ... what am I missing?
Thanks
You can create a model form that adjusts specific field's queryset dynamically when working with existing model instance.
### in my_app/models.py ###
class AdministrativeArea(models.Model):
type = models.CharField(max_length=1, choices=choices.ADMIN_AREA_TYPES)
name = models.CharField(max_length=60, unique=True)
parent = models.ForeignKey('AdministrativeArea',
null=True,
blank=True,
limit_choices_to = Q(type__neq='p')
)
### in my_app/admin.py ###
from django.contrib import admin
import django.forms as forms
from my_app.models import AdministrativeArea
class class AdministrativeAreaAdminForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(AdministrativeAreaAdminForm, self).__init__(*args, **kwargs)
instance = kwargs.get('instance', None)
if instance is not None:
parentField = self.fields['parent']
parentField.queryset = parentField.queryset.filter(type__neq=instance.type)
class Meta:
model = AdministrativeArea
class AdministrativeAreaAdmin(admin.ModelAdmin):
form = AdministrativeAreaAdminForm
Such form could be used also outside admin site if you need the filtering there.