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Django REST: ignoring custom fields which are not part of model

My TimeReport model looks like this:
class TimeReport(models.Model):
minutes_spent = models.PositiveIntegerField()
task = models.ForeignKey(Task, on_delete=models.CASCADE)
created_at = models.DateTimeField(auto_now_add=True)
modified_at = models.DateTimeField(auto_now=True)
reported_for = models.DateField()
note = models.TextField(null = True, blank=True)
status = models.CharField(max_length=50, choices=State.choices, default=State.new)
user = models.ForeignKey(User, on_delete=models.PROTECT)
And my model serializer:
class TimeReportCreateSerializer(serializers.ModelSerializer):
class Meta:
model = TimeReport
fields = (
'id',
'minutes_spent',
'reported_for',
'note',
'status',
'task_custom_id',
)
task_custom_id = serializers.CharField()
def create(self, validated_data):
user = User.objects.get(auth_user_id = self.context['user_id'])
task = Task.objects.filter(custom_id = validated_data['task_custom_id']).filter(user = user.id).first()
report = TimeReport(**validated_data)
report.user = user
report.task = task
report.save()
return report
So, the problem is, that I want to take a custom value in a serializer, which is not a part of a model and do some custom logic with it - in this case search for the right 'task' in the database. But when I try to parse the model by using report = TimeReport(**validated_data), it gives me an exception:
TypeError at /api/report/
TimeReport() got an unexpected keyword argument 'task_custom_id'
Im kind of new to Django and python itself, so - what is the best approach?

If you are going to use that field only for creation, you should use write_only option.
task_custom_id = serializers.CharField(write_only=True)
See the docs here https://www.django-rest-framework.org/api-guide/fields/#write_only

You just need to remove task_custom_id from the dictionary
class TimeReportCreateSerializer(serializers.ModelSerializer):
class Meta:
model = TimeReport
fields = (
'id',
'minutes_spent',
'reported_for',
'note',
'status',
'task_custom_id',
)
task_custom_id = serializers.CharField()
def create(self, validated_data):
user = User.objects.get(auth_user_id = self.context['user_id'])
task_custom_id = validated_data.pop("task_custom_id")
task = Task.objects.filter(custom_id = task_custom_id).filter(user = user.id).first()
report = TimeReport(**validated_data)
report.user = user
report.task = task
report.save()
return report

task = Task.objects.filter(custom_id = validated_data.pop('task_custom_id')).filter(user = user.id).first()
the **validated_data will return (task_custom_id=value, field1=value1 ...) and task_custom_id it's not a TimeReport field so all u need is to pop it from validated_data before calling the constructor TimeReport

Django Models Select a car model based on Car Make

Somewhat new to Django and I'm trying to create a car listing site. I've already ran into problems with the models. I can't seem figure out how I can create a model where if you select a particular make (e.g. Dodge) then you can select a model related to that make (e.g. Charger, Challenger, Viper etc.) or if you selected McLaren you could select from the 720s, 765lt, Senna, P1 etc.
models.py
class Make(models.Model):
make = models.CharField('Make', max_length=150)
class Meta:
ordering = ['make']
unique_together = ["make"]
verbose_name_plural = "Manufacturers"
def __str__(self):
return self.make
class CarModel(models.Model):
year = models.IntegerField(default=datetime.datetime.today().year)
make = models.ForeignKey(Make, on_delete=models.CASCADE)
model = models.CharField('Model', max_length=150)
trim = models.CharField('Trim', max_length=150, help_text='Trim level')
class Meta:
ordering = ['make', 'model', 'trim', 'year']
unique_together = ("year", "make", "model", "trim")
verbose_name_plural = "Models"
def __str__(self):
return f' {self.year} {self.make} {self.model} {self.trim}'
class CarListing(models.Model):
content = models.FileField("Media")
make = models.ForeignKey(Make, on_delete=models.CASCADE)
make_model = models.ForeignKey(CarModel, on_delete=models.CASCADE)
class Meta:
ordering = ['make_model']
verbose_name_plural = "Car Listings"
def __str__(self):
return f' {self.make_model.year} {self.make_model.make}
{self.make_model.model}
{self.make_model.trim} '

Use related_name for backwards compatibility.
class CarModel(models.Model):
year = models.IntegerField(default=datetime.datetime.today().year)
make = models.ForeignKey(Make, on_delete=models.CASCADE, related_name="models") # Note the related name here
model = models.CharField('Model', max_length=150)
trim = models.CharField('Trim', max_length=150, help_text='Trim level')
Then when you have a related name, you can easily access it by calling models on an instance
make = Make.objects.get(make="Dodge")
print(make.models) # Viper, Charger, Challenger, etc.
Note: make = Make.objects.get(make="Dodge") this will fire you an error if there are multiple records with the same query.
So you have to do something like this:
make = Make.objects.filter(make="Dodge") # return list of records`

TypeError: einsatznummer_generator() missing 1 required positional argument: 'self'

I have tried to add a kind of custom id to my Django model, which is built according to the date of a model field. This should be built according to the format: [year][number]. (e.g. 2021001, 2021002, 2021003..., 2022001)
For this purpose, I have designed the following model, which returns the error:
TypeError: insert_number_generator() missing 1 required positional argument: 'self'.
Because of einsatznummer_generator() is not a class, I don't have to initialise it. Can someone please explain the error in my Custom ID?
my models.py:
from django.db import models
from django.contrib.auth.models import User
from django.utils import timezone
from django.db.models.fields import CharField, NullBooleanField
import datetime
class EinsatzPublic(models.Model):
STATUS = (
(0,"Entwurf"),
(1,"Öffentlich"),
(2,"Archiv"),
(3,"Papierkorb"),
)
author = models.ForeignKey('auth.User', on_delete=models.CASCADE, editable=False, verbose_name="Autor")
created = models.DateTimeField(default=timezone.now, editable=False, verbose_name="Erstellt")
updated = models.DateTimeField(auto_now= True, editable=False, verbose_name="Aktualisiert")
status = models.IntegerField(choices=STATUS, default=0, verbose_name="Status")
einsatz_start = models.DateTimeField(verbose_name="Einsatzbeginn")
einsatz_end = models.DateTimeField(verbose_name="Einsatzende")
#! Custom ID:
def einsatznummer_generator(self):
year_einsatz = self.einsatz_start.strftime('%Y')
last_number = EinsatzPublic.objects.filter(einsatznummer__isnull=False).latest('einsatznummer')
if last_number == None:
last_number = 000
elif last_number[:-3] != year_einsatz:
last_number = 000
einsatznummer_gen = year_einsatz + (last_number + 1)
return einsatznummer_gen
einsatznummer = models.IntegerField(default=einsatznummer_generator() ,verbose_name="Einsatznummer", editable=False)
class Meta:
ordering = ['-created']
verbose_name = "Einsatz"
verbose_name_plural = "Einsätze"

Edit because I did not understand your question correctly:
You can't generate a default value based on other fields of the object because if the object doesn't exist yet, those fields don't exist too.
What you can do is define a model property with the #property decorator:
class EinsatzPublic(models.Model):
STATUS = (
(0,"Entwurf"),
(1,"Öffentlich"),
(2,"Archiv"),
(3,"Papierkorb"),
)
author = models.ForeignKey('auth.User', on_delete=models.CASCADE, editable=False, verbose_name="Autor")
created = models.DateTimeField(default=timezone.now, editable=False, verbose_name="Erstellt")
updated = models.DateTimeField(auto_now= True, editable=False, verbose_name="Aktualisiert")
status = models.IntegerField(choices=STATUS, default=0, verbose_name="Status")
einsatz_start = models.DateTimeField(verbose_name="Einsatzbeginn")
einsatz_end = models.DateTimeField(verbose_name="Einsatzende")
#property
def einsatznummer(self):
year_einsatz = self.einsatz_start.strftime('%Y')
last_number = EinsatzPublic.objects.filter(einsatznummer__isnull=False, einsatz_start__year=year_einsatz).latest('id').einsatznummer
if last_number == None:
last_number = 000
elif last_number[:-3] != year_einsatz:
last_number = 000
einsatznummer_gen = year_einsatz + (last_number + 1)
return einsatznummer_gen
class Meta:
ordering = ['-created']
verbose_name = "Einsatz"
verbose_name_plural = "Einsätze"
Then you can access the einsatznummer property like any other field.

It's method, so you need to call it via self.
default=self.einsatznummer_generator
And do not call the function, pass it without parantheses.

Django ForeignKey accept two models

I'm working on this big project with Django and I have to update the database. I have to add another table which will replace another later.
So I want to add in a model the possibility to have a field where I can have either the old model OR the new one.
Here is the code of the old model:
class Harvests(models.Model):
ident_culture = models.IntegerField(primary_key=True)
intitule_culture = models.CharField(max_length=50, blank=True)
nom_fertiweb = models.CharField(max_length=50, blank=True, null = True)
affichage_quintaux_tonne = models.CharField(max_length=1,
choices=RENDEMENT_CHOICES, default = 'T')
type_culture = models.ForeignKey("TypeCulture", null=True)
slug = models.SlugField(null=True, blank=True)
image = models.ImageField(upload_to = 'images_doc_culture/',
null=True, blank = True)
affichage = models.BooleanField(default = True)
class Meta:
verbose_name = "Liste - Culture"
verbose_name_plural = "Liste - Cultures"
ordering = ['intitule_culture']
def __str__(self):
return self.intitule_culture
def label(self):
return self.intitule_culture or ''
#classmethod
def get_choices(cls):
choices = [('', corp.EMPTY_CHOICE_LBL)]
c_category_lbl, c_category = '', []
for item in cls.objects.all():
choices.append((item.pk, item.intitule_culture))
return choices
And there is the code od the new one I created:
class Crops(models.Model):
intitule_culture = models.CharField(max_length=75, blank=True)
affichage_quintaux_tonne = models.CharField(max_length=2,
choices=RENDEMENT_CHOICES, default = 'T')
type_culture = models.ForeignKey("TypeCulture", null=True)
ident_culture = models.IntegerField(primary_key=True)
affichage = models.BooleanField(default = True)
id_marle = models.IntegerField(null=True)
class Meta:
verbose_name = "Liste - Culture 2019"
verbose_name_plural = "Liste - Cultures 2019"
ordering = ['intitule_culture']
def __str__(self):
return self.intitule_culture
def label(self):
return self.intitule_culture or ''
#classmethod
def get_choices(cls):
choices = [('', corp.EMPTY_CHOICE_LBL)]
c_category_lbl, c_category = '', []
for item in cls.objects.all():
choices.append((item.pk, item.intitule_culture))
return choices
I want to accept both models in the field culture in this model:
class CompanyHarvest(models.Model):
company = models.ForeignKey('corp.Company', verbose_name='Exploitation',
related_name ='cultures')
culture = models.ForeignKey(Harvests, verbose_name ='Culture')
precision = models.CharField(max_length=255, blank=True)
saison_culture = models.CharField(max_length=1, choices=SAISON_CHOICES,
default = 'P')
class Meta:
verbose_name = "Expl. - Culture"
verbose_name_plural = "Expl. - Cultures"
unique_together = ('company', 'culture', 'precision', 'saison_culture')
def __str__(self):
return str(self.culture) + ' ' + self.precision + \
' ' + str(self.get_saison_culture_display() )
#property
def slug(self):
return "_".join([slugify(str(self.culture or '')),
slugify(str(self.precision or ''))]
)
I'm new to Django, can anyone help me with this please ? (^-^)

This is not possible - at least not this way. And this is not a Django limitation but a SQL one, a foreign key cannot reference either one table or another.
A possible and simple obvious solution here would be to have two foreign keys in CompanyHarvest - one for each of the old and new model -, each with blank=True et default=None, but it can quickly make a mess of all the client code (all code using CompanyHarvest).
Much better solutions would be to either only keep the existing model (adding any new field/feature to it and eventually hiding obsolete ones) or migrate all old model records to the new model (this can be combined with the naive "two foreign keys" solution so you can keep the old table and records as archives if necessary).
Also - totally unrelated but -, this:
#classmethod
def get_choices(cls):
choices = [('', corp.EMPTY_CHOICE_LBL)]
c_category_lbl, c_category = '', []
for item in cls.objects.all():
choices.append((item.pk, item.intitule_culture))
return choices
1/ should be defined on the manager (cf https://docs.djangoproject.com/en/2.1/topics/db/managers/#adding-extra-manager-methods)
2/ should be written using .values() queryset (which will save on both the db query and building full-blown instances for no good reason):
for item in cls.objects.values("pk", "intitule_culture"):
choices.append(item)
3/ and could very possibly (i'd have to see how it's used) replaced by a ModelChoiceField in the calling code.
Oh and yes: if you allow blanks for text fields, you very probably want to force the empty string as default so you don't two possible (and incompatible) cases (sql NULL and the empty string) when no value is given.

Manager object has no attribute 'save'

In my serializers.py I have a OrderCreateSerializer:
class OrderCreateSerializer(ModelSerializer):
data_params = serializers.DictField() # 根据产品数据模型不同而异
class Meta:
model = Order
fields = (
"product_describe", # 产品描述 (购买xx产品 + 参数)
"billing_type", # 计费类型 ("包年包月")
"data_params", # 数据
)
def create(self, validated_data):
request = self.context.get("request")
if request and hasattr(request, "user"):
user = request.user
validated_data["order_num"] = generateOrderNum(userid=user.id)
validated_data["order_status"] = "未支付"
validated_data["order_status"] = "未支付"
data_dic = validated_data.pop("data_params") #
# data_dic["data"]["profile"]
validated_data["buytime"] = data_dic["data"]["buytime"]
validated_data["count"] = data_dic["data"]["count"]
validated_data["paytype"] = ""
validated_data["cost"] = ""
validated_data["account"] = user.account
return Order.objects.save(**validated_data) # this is the line 57
When I save the validated_data, it report the bellow error:
Manager object has no attribute 'save'
My Order model is like bellow, there is many fields in it :
class Order(models.Model):
"""
订单
"""
order_num = models.CharField(max_length=128, unique=True) # 订单编号
order_status = models.CharField(max_length=12) # 订单状态 "未支付"， "已支付，未完成"， "已完成"， "已经删除"，"其他"
product_describe = models.TextField() # 产品描述
billing_type = models.CharField(max_length=16) # 计费类型
buytime = models.CharField(max_length=16) # 比如：1月 永久
count = models.IntegerField() # 购买数量
paytype = models.CharField(max_length=16) # 支付方式（支付包，微信，xxx）
cost = models.DecimalField(max_digits=8, decimal_places=2, default=0.00) # 费用（需要花费多少钱）
account = models.ForeignKey(to=Account) # 所属账户
ctime = models.DateTimeField(auto_now_add=True) # 创建时间
uptime = models.DateTimeField(auto_now=True) # 更新时间
def __str__(self):
return self.product_describe
def __unicode__(self):
return self.product_describe
I don't know why there is the Manager object here.

You're calling save on the manager (ie, objects)
return Order.objects.save(**validated_data)
You call save on models.
I assume you're trying to create the model, in which case you want create.
return Order.objects.create(**validated_data)

Order.objects is an instance of the Manager class. The save method is a method of the model class.
Try:Order(**validated_data).save()