We Keep Coding

Django Rest Framework issue in def create method..facing null value in trial end field

There is a trial end field in subscription model, i want to initialize the field with trial_end_date ,
problem I'm facing now trial_end in subscription model showing null value, How can I extract out the field of trial end field and initialize it? I have attached the def create method looked at that.
I will appreciate your help .
def create(self, validated_data):
subscriptions_data = validated_data.pop('plan')
print(subscriptions_data)
user_memberships = UserMembership.objects.create(**validated_data)
trial_end = user_memberships.membership.get_trial_period_days()
trial_end_date = datetime.date.today() + datetime.timedelta(trial_end)
for subscription_data in subscriptions_data:
Subscription.objects.create(user_membership=user_memberships, **subscription_data,)
return user_memberships
[Model][2]
my aim is when in membership model plan contain trial period days , it will add in trial end field of subscription model

Probably because you are not passing trial_end_date's value in Subscription.objects.create(..). So you can fix it like this:
trial_end = user_memberships.membership.get_trial_period_days()
trial_end_date = datetime.date.today() + datetime.timedelta(trial_end)
for subscription_data in subscriptions_data:
Subscription.objects.create(trial_end = trial_end_date, user_membership=user_memberships, **subscription_data,)

How to do efficient reverse foreign key check on Django multi-table inheritance model?

I've got file objects of different types, which inherit from a BaseFile, and add custom attributes, methods and maybe fields. The BaseFile also stores the File Type ID, so that the corresponding subclass model can be retrieved from any BaseFile object:
class BaseFile(models.Model):
name = models.CharField(max_length=80, db_index=True)
size= models.PositiveIntegerField()
time_created = models.DateTimeField(default=datetime.now)
file_type = models.ForeignKey(ContentType, on_delete=models.PROTECT)
class FileType1(BaseFile):
storage_path = '/path/for/filetype1/'
def custom_method(self):
<some custom behaviour>
class FileType2(BaseFile):
storage_path = '/path/for/filetype2/'
extra_field = models.CharField(max_length=12)
I also have different types of events which are associated with files:
class FileEvent(models.Model):
file = models.ForeignKey(BaseFile, on_delete=models.PROTECT)
time = models.DateTimeField(default=datetime.now)
I want to be able to efficiently get all files of a particular type which have not been involved in a particular event, such as:
unprocessed_files_type1 = FileType1.objects.filter(fileevent__isnull=True)
However, looking at the SQL executed for this query:
SELECT "app_basefile"."id", "app_basefile"."name", "app_basefile"."size", "app_basefile"."time_created", "app_basefile"."file_type_id", "app_filetype1"."basefile_ptr_id"
FROM "app_filetype1"
INNER JOIN "app_basefile"
ON("app_filetype1"."basefile_ptr_id" = "app_basefile"."id")
LEFT OUTER JOIN "app_fileevent" ON ("app_basefile"."id" = "app_fileevent"."file_id")
WHERE "app_fileevent"."id" IS NULL
It looks like this might not be very efficient because it joins on BaseFile.id instead of FileType1.basefile_ptr_id, so it will check ALL BaseFile ids to see whether they are present in FileEvent.file_id, when I only need to check the BaseFile ids corresponding to FileType1, or FileType1.basefile_ptr_ids.
This could result in a significant performance difference if there are a very large number of BaseFiles, but FileType1 is only a small subset of that, because it will be doing a large amount of unnecessary lookups.
Is there a way to force Django to join on "app_filetype1"."basefile_ptr_id" or otherwise achieve this functionality more efficiently?
Thanks for the help
UPDATE:
Using annotations and Exists subquery seems to do what I'm after, however the resulting SQL still appears strange:
unprocessed_files_type1 = FileType1.objects.annotate(file_event=Exists(FileEvent.objects.filter(file=OuterRef('pk')))).filter(file_event=False)
SELECT "app_basefile"."id", "app_basefile"."name", "app_basefile"."size", "app_basefile"."time_created", "app_basefile"."file_type_id", "app_filetype1"."basefile_ptr_id",
EXISTS(
SELECT U0."id", U0."file_id", U0."time"
FROM "app_fileevent" U0
WHERE U0."file_id" = ("app_filetype1"."basefile_ptr_id"))
AS "file_event"
FROM "app_filetype1"
INNER JOIN "app_basefile" ON ("app_filetype1"."basefile_ptr_id" = "app_basefile"."id")
WHERE EXISTS(
SELECT U0."id", U0."file_id", U0."time"
FROM "app_fileevent" U0
WHERE U0."file_id" = ("app_filetype1"."basefile_ptr_id")) = 0
It appears to be doing the WHERE EXISTS subquery twice instead of just using the annotated 'file_event' label... Maybe this is just a Django/SQLite driver bug?

Associate classes with django-filters

Bonjour, I have a question regarding django-filters. My problem is:
I have two classes defined in my models.py that are:
class Volcano(models.Model):
vd_id = models.AutoField("ID, Volcano Identifier (Index)",
primary_key=True)
[...]
class VolcanoInformation(models.Model):
# Primary key
vd_inf_id = models.AutoField("ID, volcano information identifier (index)",
primary_key=True)
# Other attributes
vd_inf_numcal = models.IntegerField("Number of calderas")
[...]
# Foreign key(s)
vd_id = models.ForeignKey(Volcano, null=True, related_name='vd_inf_vd_id',
on_delete=models.CASCADE)
The two of them are linked throught the vd_id attribute.
I want to develop a search tool that allows the user to search a volcano by its number of calderas (vd_inf_numcal).
I am using django-filters and for now here's my filters.py:
from .models import *
import django_filters
class VolcanoFilter(django_filters.FilterSet):
vd_name = django_filters.ModelChoiceFilter(
queryset=Volcano.objects.values_list('vd_name', flat=True),
widget=forms.Select, label='Volcano name',
to_field_name='vd_name',
)
vd_inf_numcal = django_filters.ModelChoiceFilter(
queryset=VolcanoInformation.objects.values_list('vd_inf_numcal', flat=True),
widget=forms.Select, label='Number of calderas',
)
class Meta:
model = Volcano
fields = ['vd_name', 'vd_inf_numcal']
My views.py is:
def search(request):
feature_list = Volcano.objects.all()
feature_filter = VolcanoFilter(request.GET, queryset = feature_list)
return render(request, 'app/search_list.html', {'filter' : feature_filter, 'feature_type': feature_type})
In my application, a dropdown list of the possible number of calderas appears but the search returns no result which is normal because there is no relation between VolcanoInformation.vd_inf_numcal, VolcanoInformation.vd_id and Volcano.vd_id.
It even says "Select a valid choice. That choice is not one of the available choices."
My question is how could I make this link using django_filters ?
I guess I should write some method within the class but I have absolutely no idea on how to do it.
If anyone had the answer, I would be more than thankful !

In general, you need to answer two questions:
What field are we querying against & what query/lookup expressions need to be generated.
What kinds of values should we be filtering with.
These answers are essentially the left hand and right hand side of your .filter() call.
In this case, you're filtering across the reverse side of the Volcano-Volcano Information relationship (vd_inf_vd_id), against the number of calderas (vd_inf_numcal) for a Volcano. Additionally, you want an exact match.
For the values, you'll need a set of choices containing integers.
AllValuesFilter will look at the DB column and generate the choices from the column values. However, the downside is that the choices will not include any missing values, which look weird when rendered. You could either adapt this field, or use a plain ChoiceFilter, generating the values yourself.
def num_calderas_choices():
# Get the maximum number of calderas
max_count = VolcanoInformation.objects.aggregate(result=Max('vd_inf_numcal'))['result']
# Generate a list of two-tuples for the select dropdown, from 0 to max_count
# e.g, [(0, 0), (1, 1), (2, 2), ...]
return zip(range(max_count), range(max_count))
class VolcanoFilter(django_filters.FilterSet):
name = ...
num_calderas = django_filters.ChoiceFilter(
# related field traversal (note the connecting '__')
field_name='vd_inf_vd_id__vd_inf_numcal',
label='Number of calderas',
choices=num_calderas_choices
)
class Meta:
model = Volcano
fields = ['name', 'num_calderas']
Note that I haven't tested the above code myself, but it should be close enough to get you started.

Thanks a lot ! That's exactly what I was looking for ! I didn't understand how the .filter() works.
What I did, for other attributes is to generate the choices but in a different way. For instance if I just wanted to display a list of the available locations I would use:
# Location attribute
loc = VolcanoInformation.objects.values_list('vd_inf_loc', flat=True)
vd_inf_loc = django_filters.ChoiceFilter(
field_name='vd_inf_vd_id__vd_inf_loc',
label='Geographic location',
choices=zip(loc, loc),
)

How to prevent field value repetition on already assigned date in Odoo?

I am working with Odoo 10.
I have a one2many field with two columns in the hr.employee model. If the field "Bonus" (many2one field) is assigned to a particular date, it should not be saved or repeated once again on the same date.
How to achieve this?

Take a look at this below code, this is one possible solution, not the best.
from odoo import models, fields, api
from odoo.exceptions import ValidationError
class HrEmployee(models.Model):
_inherit = 'hr.employee'
prod_details_ids = fields.One2many(
string=u'Product details',
comodel_name='prod.details',
inverse_name='employee_id',
)
class ProdDetails(models.Model):
_name = 'prod.details'
employee_id = fields.Many2one(
string=u'Employee',
comodel_name='hr.employee',
)
date = fields.Date(
string=u'Date',
default=fields.Date.context_today,
)
bonus_id = fields.Many2one(
string=u'Bonus',
comodel_name='res.partner', # just an example
)
And then you need to add the constrains:
Solution 1
_sql_constraints = [
('bonus_unique', 'unique(employee_id, date, bonus_id)',
_('Date + Bonus cannot be repeated in one employee!')),
]
Solution 2
#api.one
#api.constrains('date', 'bonus_id')
def _check_unique_date(self):
# you have more freedom here if you want to check more things
rest = self.employee_id.prod_details_ids - self
for record in rest:
if record.date == self.date and record.bonus_id.id == self.bonus_id.id:
raise ValidationError("Date + Bonus already exists and violates unique field constraint")
Note: If you have date already in your database make sure that the constrains can be added with this data, because if not the constraint cannot be added to the database. This happens with the _sql_constraints at least

Use constrains to stop creating another record with the same name, so duplication of records doesnot occur.

you can use constraints and the search_count() method to check if there is a record. like below
#api.constraints('date')
def validate_date(self):
result = self.search_count([your_domain])
if result:
raise ValidationError(_('Your Text'))

Django IntegerField returns ExpressionNode

I got a model containing two counters :
class MyObject(models.Model):
...
student_c = models.PositiveIntegerField(default=0, blank=True, null=True)
company_c = models.PositiveIntegerField(default=0, blank=True, null=True)
def total_followers(self):
return self.student_c + self.company_c
one is working perfectly and returns an integer value but the other one returns :
django.db.models.expressions.ExpressionNode object at 0x7ff4d8320a10
I tried to change PositiveIntegerField to IntegerField and to rename the field with another name but I still get the same result ? I destroyed the database and rebuilt it many times
In my template I can see this : (+: (DEFAULT: ), 1)
In fact I'm trying to do an atomic increment like this:
project = get_object_or_404(Project, pk=kwargs['pk'])
project.student_c = F('student_c') + 1
project.save(update_fields=['student_c']) or even just project.save()
This is where the problem is coming from. I looked there and I found the same code :
Atomic increment of a counter in django
What am I doing wrong ?
Any help would be very appreciated.
Thanks

I'm not sure you're using the F() object correctly. Have you tried just doing
Projects.objects.filter(pk=kwargs['pk']).update(student_c=F('student_c') + 1)
That would replace those three lines. Also you could try this for the second line:
project.student_c = project.student_c + 1

I don't know if this is similar to your problem, but maybe can help you
http://www.voidspace.org.uk/python/weblog/arch_d7_2011_04_30.shtml
Maybe you need to call .save before call total_followers in your view...
For example:
import model.MyObject
myObj = MyObject.objects.create(....)
myObj.save()
myObj.total_followers()