Select values from two tables using Django - django

Question

I have two tables as follows,
cabinet
cabinet_id cabinet_name
1 Test1
2 Test2
3 Test3
cabinet_maping
id product_id cabinet_id size
1 34 1 20
2 34 3 25
How can I select all cabinet_name from cabinet table where cabinet_maping.product_id = 34 in Django
Expected Output as follows,
cabinet_id cabinet_name size
1 Test1 20
2 Test2 0
3 Test3 25

Answer 1

I think that yours models could look like
class Cabinet(models.Model):
name = models.CharField(max_length = 30)
class cabinet_maping(models.Model):
product = models.ForeignKey(Product)
cabinet = models.ForeignKey(Cabinet)
size = .....
You should do sth like this:
cabinet_name = cabinet_maping.objects.filter(product__id = 34)
for item in cabinet_name:
print item.cabinet.id
print item.cabinet.name
print item.size
I didn't check it but i think that should work (that works :))

Answer 2

I agree with Silwestpl that your models are wrong as using Foreign Key would make this query a lot easier. But just an answer to your question would be. I am assuming that you dont have any relationships between the two tables as you haven't mentioned any.
x = Cabinet_mapping.objects.filter(product_id = somevalue).distinct('cabinet_id')
response_list = []
for y in x:
response_dict = {}
response_dict['cabinet_id'] = y.cabinet_id
response_dict['cabinet_name'] = cabinet.objects.get(id = y.cabinet_id).cabinet_name
response_dict['size'] = y.size
response_list.append(response_dict)
return response_list
This would be the answer according to the details you have provided.
But Ideally I would do something like this
class Product(models.Model):
# id is generated automatically.
## any other fields that you want for product.
class Cabinet(models.Model):
# again id is auto-genearated.
cabinet_name = models.CharField(max_length=100)
cabinet_size = models.IntegerField()
products = models.ManytoManyField(Product)#This automatically maps product_id n cabinet_id.
And your query would be.
x = Cabinet.objects.filter(product.id=some_value)
print (x.id , x.cabinet_name, x.cabinet_size) # I used print, but you can use it anyway you want.
This would be what you require. Please use the second solution if you are looking into something serious.