How can I get the foreign key values? I have a common vehicle model that links to the year, series, engine type, body style, transmission and drive train...all as foreign keys. I'd like to get the values of these fields for my app, but I'm stuck as to how I'd go about them. Any ideas will be highly appreciated.
class Model(models.Model):
model = models.CharField(max_length=15, blank=False)
manufacturer = models.ForeignKey(Manufacturer)
date_added = models.DateField()
def __unicode__(self):
name = ''+str(self.manufacturer)+" "+str(self.model)
return name
class Year(models.Model):
ALPHA_NUMERIC_CHOICES = (
('1', 'Numeric'),
('A', 'Alphabetic'),
)
year = models.PositiveSmallIntegerField()
position_7_char = models.CharField(max_length=1, choices=ALPHA_NUMERIC_CHOICES)
position_10 = models.CharField(max_length=1, blank=False)
def __unicode__(self):
return unicode(self.year)
class Series(models.Model):
series = models.CharField(max_length=20, blank=True)
model = models.ForeignKey(Model)
date_added = models.DateField()
def __unicode__(self):
name = str(self.model)+" "+str(self.series)
return name
class CommonVehicle(models.Model):
year = models.ForeignKey(Year)
series = models.ForeignKey(Series)
engine = models.ForeignKey(Engine)
body_style = models.ForeignKey(BodyStyle)
transmission = models.ForeignKey(Transmission)
drive_train = models.ForeignKey(DriveTrain)
def __unicode__(self):
name = ''+str(self.year)+" "+str(self.series)
return name
class Vehicle(models.Model):
stock_number = models.CharField(max_length=6, blank=False)
vin = models.CharField(max_length=17, blank=False)
common_vehicle = models.ForeignKey(CommonVehicle)
exterior_colour = models.ForeignKey(ExteriorColour)
interior_colour = models.ForeignKey(InteriorColour)
interior_type = models.ForeignKey(InteriorType)
odometer_unit = models.ForeignKey(OdometerUnit)
status = models.ForeignKey(Status)
odometer_reading = models.PositiveIntegerField()
selling_price = models.PositiveIntegerField()
purchase_date = models.DateField()
sales_description = models.CharField(max_length=60, blank=False)
def __unicode__(self):
return self.stock_numberodels.ForeignKey(CommonVehicle)
You need the actual IDs? Try something like my_vehicle_ref.series.id.
Also, I hope you know that the series attribute right there is really an instance of Series, so you could access any of it's properties, e.g., my_vehicle_ref.series.model.model.
Related
I have a Warehouse model like the following:
class ShelfBin(models.Model):
bin_id = models.IntegerField(default=0)
bin_name = models.CharField(max_length=50, default=0)
class UnitShelf(models.Model):
shelf_id = models.IntegerField(default=0)
shelf_name = models.CharField(max_length=50, default=0)
bin = models.ManyToManyField(ShelfBin, blank=True)
class AisleUnit(models.Model):
unit_id = models.IntegerField(default=0)
unit_name = models.CharField(max_length=50, default=0)
shelf = models.ManyToManyField(UnitShelf, blank=True)
class ZoneAisle(models.Model):
aisle_id = models.IntegerField(default=0)
aisle_name = models.CharField(max_length=50, default=0)
unit = models.ManyToManyField(AisleUnit, blank=True)
class WarehouseZone(models.Model):
zone_id = models.IntegerField(default=0)
zone_name = models.CharField(max_length=50, default=0)
aisle = models.ManyToManyField(ZoneAisle, blank=True)
class Warehouse(models.Model):
owner = models.ForeignKey(User, on_delete=models.CASCADE)
name = models.CharField(max_length=250, default=0)
address = models.CharField(max_length=500, default=0)
zones = models.ManyToManyField(WarehouseZone, blank=True)
for this I have created a serializer like the following:
class WarehouseSerializer(serializers.ModelSerializer):
zones = WarehouseZonesSerializer(many=True)
class Meta:
model = Warehouse
fields = "__all__"
def create(self, validated_data):
print("validated data warehouse", validated_data)
zone_objects = validated_data.pop('zones', None)
instance = Warehouse.objects.create(**validated_data)
for item in zone_objects:
aisle_objects = item.pop('aisle')
wz_obj = WarehouseZone.objects.create(**item)
for data in aisle_objects:
unit_objects = data.pop('unit')
za_obj = ZoneAisle.objects.create(**data)
for u_data in unit_objects:
shelf_objects = u_data.pop('shelf')
au_obj = AisleUnit.objects.create(**u_data)
for s_data in shelf_objects:
bin_objects = s_data.pop('bin')
us_obj = UnitShelf.objects.create(**s_data)
for b_data in bin_objects:
b_obj = ShelfBin.objects.create(**b_data)
us_obj.bin.add(b_obj)
au_obj.shelf.add(us_obj)
za_obj.unit.add(au_obj)
wz_obj.aisle.add(za_obj)
instance.zones.add(wz_obj)
return instance
Now the problem is that sometimes warehouse can have zone, aisle, units, etc(all 5 sub-levels) but sometimes it can only be 1,2 or 0 level deep
and in that cases it raises error like this :
aisle_objects = item.pop('aisle')
KeyError: 'aisle'
So do I have to use try and except at each level of the loop or is there a better way to handle these exceptions?
My lab has a models.py as below:
class Book(models.Model):
isbn = models.CharField(max_length=10, unique=True)
name = models.CharField(max_length=100)
published_year = models.IntegerField()
total_qty = models.IntegerField()
current_qty = models.IntegerField()
max_duration = models.IntegerField()
author = models.ForeignKey(Author, on_delete=models.PROTECT)
category = models.ForeignKey(Category, on_delete=models.PROTECT)
def __str__(self):
return self.name
class BookCopy(models.Model):
class Status:
AVAILABLE = 1
BORROW =2
LOST = 3
barcode = models.CharField(max_length=30, unique=True)
buy_date = models.DateField(null=True, blank=True)
status = models.IntegerField()
book = models.ForeignKey(Book, on_delete=models.PROTECT)
def __str__(self):
return self.barcode
class User(models.Model):
username = models.CharField(max_length=30, unique=True)
fullname = models.CharField(max_length=100, null=True)
phone = models.CharField(max_length=10, null=True)
def __str__(self):
return self.fullname
class BookBorrow(models.Model):
class Status:
BORROWING = 1
RETURNED = 2
borrow_date = models.DateField()
deadline = models.DateField()
return_date = models.DateField(null=True)
status = models.IntegerField()
book_copy = models.ForeignKey(BookCopy, on_delete=models.PROTECT)
book_name = models.ForeignKey(Book, on_delete=models.PROTECT)
user = models.ForeignKey(User, on_delete=models.PROTECT)
And i wrote the api for borrow_book function like below:
#csrf_exempt
def muon_sach(request):
body = request.POST
username = body.get('username')
barcode = body.get('barcode')
user = User.objects.filter(username=username).first()
bookcopy = BookCopy.objects.filter(barcode = barcode).first()
if not user:
return HttpResponse(json.dumps({
'error':"Nguoi dung khong ton tai"
}))
if not bookcopy:
return HttpResponse(json.dumps({
'error':"ma sach khong ton tai"
}))
book_borrow = BookBorrow()
# resp = []
book_borrow.user = user
book_borrow.book_copy = bookcopy
book_borrow.borrow_date = datetime.now()
book_borrow.deadline = datetime.now() + timedelta(days=bookcopy.book.max_duration)
book_borrow.status = BookBorrow.Status.BORROWING
book_borrow.book_name = bookcopy.book.name
book_borrow.save()
bookcopy.status = BookCopy.Status.BORROW
bookcopy.save()
bookcopy.book.current_qty -=1
bookcopy.book.save()
return HttpResponse(json.dumps({'success':True}))
however when i test with postman (give username and barcode), it gets the error
xxx "BookBorrow.book_name" must be a "Book" instance."
Could you please advise where incorrect and assist me correct it ? Appreciate for any assist
You have to do the following:
#csrf_exempt
def muon_sach(request):
# ... more code here
bookcopy = BookCopy.objects.filter(barcode = barcode).first()
book_borrow.book_name = bookcopy.book
book_borrow.save()
# ... more code here
return HttpResponse(json.dumps({'success':True}))
So in the definition of your model you can see that book_name has the following structure:
class BookBorrow(models.Model):
# ... More code here
book_name = models.ForeignKey(Book, on_delete=models.PROTECT)
user = models.ForeignKey(User, on_delete=models.PROTECT)
It is clear that BookBorrow.book_name must accept a Book instance. So when you pass in you code book_borrow.book_copy = bookcopy it is passing a BookCopy instance so that's the error.
borrow_copy.book is the appropiate.
You have specified book_name to be a Foreign Key to Book, and you try to assign to it the book.name value.
Either you need to set this field as a CharField or you need to rename the field from book_name to book and use book_borrow.book = bookcopy.book
My table named Value has a one to many relationship with the table Country and the table Output_outcome_impact. I have a query that is working fine and gets what I want but then I need to do an average of the value field, but this average needs to be done for each unique id_output_outcome_impact and not the whole query.
class Country(models.Model):
country_name = models.CharField(max_length=255, primary_key=True)
CONTINENTCHOICE = (
('Africa', 'Africa'),
('America', 'America'),
('Asia', 'Asia'),
('Europe', 'Europe'),
('Oceania', 'Oceania')
)
region = models.CharField(max_length=255)
continent = models.CharField(max_length=255, choices=CONTINENTCHOICE)
GDP_per_capita = models.IntegerField(null=True)
unemployment_rate = models.FloatField(null=True)
female_unemployment_rate = models.FloatField(null=True)
litteracy_rate = models.FloatField(null=True)
def __str__(self):
return self.country_name
class OutputOutcomeImpact(models.Model):
output_outcome_impact_name = models.CharField(max_length=255, primary_key=True)
TYPECHOICE = (
('Output', 'Output'),
('Outcome', 'Outcome'),
('Impact', 'Impact'),
)
type = models.CharField(max_length=255, choices=TYPECHOICE)
description = models.TextField()
TARGETGROUP = (
('Standard', 'Standard'),
('Investors', 'Investors'),
('Local authorities and NGOs', 'Local authorities and NGOs'),
)
target_group = models.CharField(max_length=255,choices=TARGETGROUP)
question = models.TextField(null=True, blank=True)
parent_name = models.ForeignKey('self', on_delete=models.PROTECT, null=True, blank=True)
indicator = models.ForeignKey(Indicator, on_delete=models.PROTECT)
def __str__(self):
return self.output_outcome_impact_name
class Activity(models.Model):
activity_name = models.CharField(max_length=255, primary_key=True)
description = models.TextField()
product_service = models.TextField()
output_outcome = models.TextField()
outcome_impact = models.TextField()
output_outcome_impacts = models.ManyToManyField('OutputOutcomeImpact')
countries = models.ManyToManyField('Country')
sectors = models.ManyToManyField('Sector')
def __str__(self):
return self.activity_name
class Value(models.Model):
value_name = models.CharField(max_length=255, primary_key=True)
country = models.ForeignKey(Country, on_delete=models.PROTECT)
id_output_outcome_impact = models.ForeignKey(OutputOutcomeImpact, on_delete=models.PROTECT)
value_has_source = models.ManyToManyField('Source')
value = models.FloatField()
function_name = models.CharField(max_length=255, default = "multiply")
def __str__(self):
return self.value_name
region_values = Value.objects.filter(id_output_outcome_impact__output_outcome_impact_name__in = output_pks, country_id__region = region).exclude(country_id__country_name = country).values()
So the result of the query is available below, and what I would like to achieve is to set the value field to an average of every object that has the same id_output_outcome_impact_id, here Dioxins and furans emissions reduction appears twice so I would like to get the 2 values set as their average.
<QuerySet [{'value_name': 'Waste_to_dioxins', 'country_id': 'Malawi', 'id_output_outcome_impact_id': 'Dioxins and furans emissions reduction', 'value': 0.0003, 'function_name': 'multiply'}, {'value_name': 'Waste_to_dioxins_south_africa', 'country_id': 'South Africa', 'id_output_outcome_impact_id': 'Dioxins and furans emissions reduction', 'value': 150.0, 'function_name': 'multiply'}, {'value_name': 'Households getting electricity per kWh', 'country_id': 'Malawi', 'id_output_outcome_impact_id': 'Households that get electricity', 'value': 0.0012, 'function_name': 'multiply'}, {'value_name': 'Dioxin to disease', 'country_id': 'Malawi', 'id_output_outcome_impact_id': 'Reduction of air pollution related diseases', 'value': 0.31, 'function_name': 'multiply'}]>
I am wondering if django models allow such modification (I went through the doc and saw the annotate function with the average but couldn't make it work for my specific case), that would be nice. Thanks.
region_values = Value.objects.filter(id_output_outcome_impact__output_outcome_impact_name__in = output_pks, country_id__region = region).exclude(country_id__country_name = country).values('id_output_outcome_impact__output_outcome_impact_name').annotate(Avg('value'))
how to get status_updation and status_date respect to the order_number
class customer_database(models.Model):
customer_id = models.CharField(max_length=20, unique=True)
customer_name = models.CharField(max_length=20)
customer_email = models.EmailField()
def __str__(self):
return self.customer_id
class order_database(models.Model):
order_number = models.CharField(max_length=10, unique=True, primary_key=True)
order_timestamp = models.DateTimeField()
order_consignment_number = models.CharField(max_length=20)
order_customer = models.ForeignKey(customer_database, on_delete=models.CASCADE)
def __str__(self):
return self.order_number
class track_database(models.Model):
order_status = models.ForeignKey(order_database, on_delete=models.CASCADE)
status_updation = models.CharField(max_length=30)
status_timestamp = models.DateTimeField()
def __str__(self):
return self.status_updation
Try
query_order_number = '1234'
tracker = track_database.objects.filter(order_status.order_number = query_order_number)
print(tracker.status_updation)
print(tracker.status_timestamp)
Let me know if this doesn't work
Or you could go via the order number:
query_order_number = '1234'
order = order_database.objects.filter(order_number = query_order_number)
print(order.track_database.status_updation)
print(order.track_database.status_timestamp)
I'm trying to make a custom backend for my system and I've hit a bit of a snag....I want to give users the ability to add new makes/models/series that are not already in the system via a form. I'm wondering how I'll go about this...my models look as below:
class Manufacturer(models.Model):
MANUFACTURER_POPULARITY_CHOICES = (
('1', 'Primary'),
('2', 'Secondary'),
('3', 'Tertiary'),
)
manufacturer = models.CharField(max_length=15, blank=False)
date_added = models.DateField()
manufacturer_popularity = models.CharField(max_length=1,
choices=MANUFACTURER_POPULARITY_CHOICES)
def __unicode__(self):
return self.manufacturer
class Model(models.Model):
model = models.CharField(max_length=20, blank=False)
manufacturer = models.ForeignKey(Manufacturer)
date_added = models.DateField()
def __unicode__(self):
name = ''+str(self.manufacturer)+" "+str(self.model)
return name
class Series(models.Model):
series = models.CharField(max_length=20, blank=True, null=True)
model = models.ForeignKey(Model)
date_added = models.DateField()
def __unicode__(self):
name = str(self.model)+" "+str(self.series)
return name
class Engine(models.Model):
ENGINE_TYPE_CHOICES = (
('H', 'H'),
('I', 'I'),
('R', 'R'),
('V', 'V'),
('W', 'W'),
)
FUEL_TYPE_CHOICES = (
('G', 'Gas'),
('D', 'Diesel'),
)
size = models.DecimalField(max_digits=2, decimal_places=1)
type = models.CharField(max_length=1, choices=ENGINE_TYPE_CHOICES)
cylinders = models.PositiveSmallIntegerField()
spec = models.CharField(max_length=20, blank=True, null=True)
fuel_type = models.CharField(max_length=1, choices=FUEL_TYPE_CHOICES)
class CommonVehicle(models.Model):
year = models.ForeignKey(Year)
series = models.ForeignKey(Series)
engine = models.ForeignKey(Engine)
body_style = models.ForeignKey(BodyStyle)
transmission = models.ForeignKey(Transmission)
speeds = models.PositiveSmallIntegerField()
drive_train = models.ForeignKey(DriveTrain)
horse_power = models.PositiveSmallIntegerField()
litre_100km_city = models.DecimalField(max_digits=3, decimal_places=1)
litre_100km_hwy = models.DecimalField(max_digits=3, decimal_places=1)
def __unicode__(self):
name = ''+str(self.year)+" "+str(self.series)
return name
This seems to be a fairly standard job for a django model form. I would recommend following the documentation at http://docs.djangoproject.com/en/dev/topics/forms/modelforms/. There are detailed instructions there on how to create a form from a model and then save the returned submission to the database.