I'm currently having some difficulty implementing dynamic choice for a field in my model. The model in question is as below.
class Item(models.Model):
# Fields
...
item_type = models.ForeignKey(Type, on_delete=models.PROTECT)
Type model
class Type(models.Model):
# Fields
group = models.CharField(max_length=50, editable=False)
name = models.CharField(max_length=30, help_text="Enter category name")
...
# Methods
def __str__(self):
return str(self.name)
What I want is to limit the number of Type returned for this field. Each of my Type entry has a 'group' field, and I only want to return the Type entry that has the same group as the group that the current user is in. For example, an user in Group "g1" when create an Item could only select Type with "g1" in group field.
I've checked out limit_choices_to, but I'm not sure how I can get the group of the user opening the form so that I can pass it into limit_choices_to. If anyone can provide an advice or any different approach to solve this it would be appreciated.
You can override default objects manager or add custom one. In your case would be something like this.
class TypesManager(models.Manager):
def get_queryset(self, user_group):
qs = super(TypesManager,self).get_queryset().filter(group_id=user_group.id)
class Type(models.Model):
group = models.ForeignKey(Group, verbose_name='Group')
name = models.CharField(max_length=30, help_text="Enter category name")
# default_manager
objects = TypesManager()
# custom_manager
custom_manager = TypesManager()
# Methods
def __str__(self):
return str(self.name)'
You can read more about Managers here https://docs.djangoproject.com/en/2.0/topics/db/managers/
Or if you want to limit types only for specific form you can filter initial data in form init
Related
I have a database representing financial transactions. Columns representing payee and category are non-optional.
However, part of my app's functionality will be to ingest external spreadsheets of transactions which do not already have payee and category information. I would then populate a form where the user will select correct payees and categories through drop-down menus, and then save the completed information to the database.
Is the correct approach to simply create two separate but equivalent classes (see below)? Or is there some way to make one a sub-class to another, despite the fact that one is connected to a database and the other is not.
# An initial class representing a transaction read from an Excel sheet
# Payee and category information are missing at this stage, but will be filled
# in by the user later on
class TransactionFromSpreadsheet:
def __init__(self, date, amount):
self.date = date
self.amount = amount
self.payee = None
self.category = None
# The Django class that will be instantiated once all the user has completed all
# necessary information
class Transaction(models.Model):
date = models.DateField()
amount = models.DecimalField(max_digits=14, decimal_places=2)
category = models.ForeignKey('Category', on_delete=models.CASCADE)
payee = models.ForeignKey('Payee', on_delete=models.CASCADE)
One could use optional foreign keys and a custom manager to provide an easy way to query the "incomplete" or "complete" transactions.
class TransactionQueryset(models.query.QuerySet):
def complete(self):
return self.filter(category__isnull=False,
payee__isnull=False)
def incomplete(self):
return self.filter(category__isnull=True,
payee__isnull=True)
class TransactionManager(models.Manager):
def get_queryset(self):
return TransactionQueryset(self.model, using=self._db)
def complete(self):
return self.get_queryset().complete()
def incomplete(self):
return self.get_queryset().incomplete()
class Transaction(models.Model):
date = models.DateField()
amount = models.DecimalField(max_digits=14, decimal_places=2)
category = models.ForeignKey('Category', on_delete=models.CASCADE,
blank=True, null=True)
payee = models.ForeignKey('Payee', on_delete=models.CASCADE,
blank=True, null=True)
objects = TransactionManager()
And if you now need an incomplete transaction you could easily get these in a view:
def view_incomplete(request):
incompletes = Transaction.objects.incomplete()
return render(request, 'incomplete_template.html',
{'incompletes': incompletes})
It is now very comfortable to gather all heavily used filter conditions in the queryset and manager class.
And if you have non complementary filter conditions you could even chain the manager functions.
I had no idea adding data to a queryset would be so hard. It's like, if it didn't come directly from the db then it might as well not exist. Even when I annotate, the new fields are 2nd class citizens and aren't always available.
Why won't serialize capture my annotate fields?
Model
class Parc(models.Model):
# Regular Django fields corresponding to the attributes in the
# world borders shapefile.
prop_id = models.IntegerField(unique=True) # OBJECTID: Integer (10.0)
shp_id = models.IntegerField()
# GeoDjango-specific: a geometry field (MultiPolygonField)
mpoly = models.MultiPolygonField(srid=2277)
sale_price = models.DecimalField(max_digits=8, decimal_places=2, null=True)
floorplan_area = models.DecimalField(max_digits=8, decimal_places=2, null=True)
price_per_area = models.DecimalField(max_digits=8, decimal_places=2, null=True)
nbhd = models.CharField(max_length=200, null=True)
# Returns the string representation of the model.
def __str__(self): # __unicode__ on Python 2
return str(self.shp_id)
Query:
parcels = Parc.objects\
.filter(prop_id__in=attrList)\
.order_by('prop_id') \
.annotate(avg_price=Avg('sale_price'),
perc_90_price=RawAnnotation('percentile_disc(%s) WITHIN GROUP (ORDER BY sale_price)', (0.9,)),
)
geojson = serialize('geojson', parcels)
When I print geojson it has no key/values for avg_price or perc_90_price. At this point, I'm leaning towards creating a dummy field and then populating it with the my customer calculations after I retrieve the queryset but I'm open to ideas.
Helper class
class RawAnnotation(RawSQL):
"""
RawSQL also aggregates the SQL to the `group by` clause which defeats the purpose of adding it to an Annotation.
"""
def get_group_by_cols(self):
return []
I use annotations with Django Rest Framework and the Serializers in that library.
In particular, the serializer method allows you to access the query set. You can do something like this.
class SomeSerializer(serializers.ModelSerializer):
avg_price = serializers.SerializerMethodField()
def get_avg_price(self, obj):
try:
return obj.avg_price
except:
return None
As mentioned by Carl Kroeger Ihl, you can also use:
class SomeSerializer(serializers.ModelSerializer):
avg_price = serializers.IntegerField(allow_null=True)
http://www.django-rest-framework.org/api-guide/fields/#serializermethodfield
So here's the issue i'm having with this Django Model.
I have a foriegn key to class SecretSantaGroup in class assignees called group.
I want to reference this fk in creator and assignee.
pretty much the data I want is like this:
creator = self.group.members
assignee = self.group.members
But I'm having issues on going about it and could use some help.
I want to be able to reference all the users in that specific group, just having trouble going about it.
class SecretSantaGroups(models.Model):
groupName = models.TextField()
members = models.ManyToManyField(User)
def __str__(self):
return self.groupName
class Meta:
verbose_name_plural = 'Secret Santa Groups'
class assignees(models.Model):
group = models.ForeignKey(SecretSantaGroups)
#person that gives gifts
creator = models.ForeignKey(self.group.members, null=True)
#person who receives gift
assignee = models.ForeignKey(self.group.members, null=True)
EDIT
---I used terrible wording, the assignees class is supposed to be who gets who in the group. 1 person gets another in each secret santa group. so gifter and giftee
class assignees(models.Model):
group = models.ForeignKey(SecretSantaGroups)
#person that gives gifts
giver = models.???(self.group.members, null=True)
#person who receives gift
giftee = models.???(self.group.members, null=True)
Unless I'm mistaken, it seems like what you're trying to do is define an association with all possible users for the SecretSantaGroup and then define which of those users is "assigned" or whatever you want to call it.
I also don't know if you want to edit these within Django admin, or part of a different view, but how I would define the model is as such:
class SecretSantaGroup(models.Model):
name = models.CharField(max_length=255)
creator = models.ForeignKey(User, related_name='creator')
members = models.ManyToMany(User, related_name='members')
assigned = models.ManyToMany(User, related_name='assigned', blank=True, null=True)
def __unicode__(self):
return self.name
If you want to limit the choices of "assigned" in Django admin, you'll need to do this in two steps. First, you would need to assign which members, then you'd need to assign the QuerySet of "assigned" to the objects in members so the choices are limited, and then you can assign which ones you want.
This can be done via a custom form. I have NOT tested this code:
class SecretSantaGroupForm(forms.ModelForm):
class Meta:
model = SecretSantaGroup
def __init__(self, *args, **kwargs):
super(SecretSantaGroupForm, self).__init__(*args, **kwargs)
self.fields['assigned'].queryset = self.instance.members.all()
Then you can assign the custom admin form on your model admin.
If you're doing this on the public side, you'll still need the same type of override, and you'll still have to do this in two steps, as best as I can tell. Hope that helps you out.
I have this model:
class Invoice(models.Model):
owner = models.ForeignKey(settings.AUTH_USER_MODEL)
data = models.TextField(default=None, blank=True, null=True)
number = models.PositiveIntegerField(default=0, null=False)
What I need is to auto-increment the field number for each separated user. The rationale is that each user has a list of Invoice, starting from number=1 to number=latest.number+1.
I do known about F() expressions, but can't figure out how to reference the latest/greatest number for each specific user. Maybe Invoice.objects.filter(owner=request.user).aggregate(Max('number')) is the path, but how do I ensure there is no race conditions between Max() and F()?
You can achieve this and similar functions by overriding save method in model and writing your custom logics to it.
class Invoice(models.Model):
owner = models.ForeignKey(settings.AUTH_USER_MODEL)
data = models.TextField(default=None, blank=True, null=True)
number = models.PositiveIntegerField(default=0, null=False)
def save(self, *args, **kwargs):
if self.pk:
self.number += 1
# Write all your logic here, like handeling max value etc
return super(Invoice, self).save(*args, **kwargs)
you can get your first or last object like this:
# For last Object
Model.objects.latest('field') # Field can be id or pk or ...
# For first Object
Model.objects.all().first() # You can also use it on filter
A simple solution is you can make the number field as the primary key since its nature would be similar.
class Invoice(models.Model):
owner = models.ForeignKey(settings.AUTH_USER_MODEL)
data = models.TextField(default=None, blank=True, null=True)
number = models.IntegerField(primary_key=True)
Or, you can make number as AutoField or BigAutoField.
number = models.AutoField()
I'd like to create a form allowing me to assign services to supplier from these models. There is no M2M relationship defined since I use a DB used by others program, so it seems not possible to change it. I might be wrong with that too.
class Service(models.Model):
name = models.CharField(max_length=30L, blank=True)
class ServiceUser(models.Model):
service = models.ForeignKey(Service, null=False, blank=False)
contact = models.ForeignKey(Contact, null=False, blank=False)
class SupplierPrice(models.Model):
service_user = models.ForeignKey('ServiceUser')
price_type = models.IntegerField(choices=PRICE_TYPES)
price = models.DecimalField(max_digits=10, decimal_places=4)
I've created this form:
class SupplierServiceForm(ModelForm):
class Meta:
services = ModelMultipleChoiceField(queryset=Service.objects.all())
model = ServiceUser
widgets = {
'service': CheckboxSelectMultiple(),
'contact': HiddenInput(),
}
Here is the view I started to work on without any success:
class SupplierServiceUpdateView(FormActionMixin, TemplateView):
def get_context_data(self, **kwargs):
supplier = Contact.objects.get(pk=self.kwargs.get('pk'))
service_user = ServiceUser.objects.filter(contact=supplier)
form = SupplierServiceForm(instance=service_user)
return {'form': form}
I have the feeling that something is wrong in the way I'm trying to do it. I have a correct form displayed but it is not instantiated with the contact and checkboxes aren't checked even if a supplier has already some entries in service_user.
You are defining services inside your Meta class. Put it outside, right after the beginning of SupplierServiceForm. At the very least it should show up then.
Edit:
I misunderstood your objective. It seems you want to show a multiple select for a field that can only have 1 value. Your service field will not be able to store the multiple services.
So, by definition, your ServiceUser can have only one Service.
If you don't want to modify the database because of other apps using it, you can create another field with a many to many relationship to Service. That could cause conflicts with other parts of your apps using the old field, but without modifying the relationship i don't see another way.
The solution to my problem was indeed to redefine my models in oder to integrate the m2m relationship that was missing, using the through argument. Then I had to adapt a form with a special init method to have all selected services displayed in checkboxes, and a special save() method to save the form using m2m relationship.
class Supplier(Contact):
services = models.ManyToManyField('Service', through='SupplierPrice')
class Service(models.Model):
name = models.CharField(max_length=30L, blank=True)
class ServiceUser(models.Model):
service = models.ForeignKey(Service, null=False, blank=False)
supplier = models.ForeignKey(Supplier, null=False, blank=False)
price = models.Decimal(max_digits=10, decimal_places=2, default=0)
And the form, adapted from the very famous post about toppings and pizza stuff.
class SupplierServiceForm(ModelForm):
class Meta:
model = Supplier
fields = ('services',)
widgets = {
'services': CheckboxSelectMultiple(),
'contact_ptr_id': HiddenInput(),
}
services = ModelMultipleChoiceField(queryset=Service.objects.all(), required=False)
def __init__(self, *args, **kwargs):
# Here kwargs should contain an instance of Supplier
if 'instance' in kwargs:
# We get the 'initial' keyword argument or initialize it
# as a dict if it didn't exist.
initial = kwargs.setdefault('initial', {})
# The widget for a ModelMultipleChoiceField expects
# a list of primary key for the selected data (checked boxes).
initial['services'] = [s.pk for s in kwargs['instance'].services.all()]
ModelForm.__init__(self, *args, **kwargs)
def save(self, commit=True):
supplier = ModelForm.save(self, False)
# Prepare a 'save_m2m' method for the form,
def save_m2m():
new_services = self.cleaned_data['services']
old_services = supplier.services.all()
for service in old_services:
if service not in new_services:
service.delete()
for service in new_services:
if service not in old_services:
SupplierPrice.objects.create(supplier=supplier, service=service)
self.save_m2m = save_m2m
# Do we need to save all changes now?
if commit:
self.save_m2m()
return supplier
This changed my first models and will make a mess in my old DB but at least it works.