Why does Django allow Circular Model Relation

[Eddilbert Macharia]

Hello All,

I was working on a project, and realized that Django does not complain when you create Circular Model relationship even when creating migrations where i expected to have this complain

e.g.  the example does not make any sense as far as relationships go but it makes my point.

class User(models.Model):  
    # ... 
    product = models.ForeignKey("Product", on_delete=models.CASCADE)
    
class Products(models.Model): 
    bought_buy = models.ForeignKey(User, on_delete=models.CASCADE)

why is this or whats the reasoning behind Django team allowing this ?

[Javier Guerra Giraldez]

On 19 February 2016 at 13:00, Eddilbert Macharia <edd....@gmail.com> wrote:
> Hello All,
>
> I was working on a project, and realized that Django does not complain when
> you create Circular Model relationship even when creating migrations where i
> expected to have this complain

why would it complain? it might be (sometimes) less than optimal, but
it's valid to have circular relationships.



--
Javier

[Vadim Serdiuk]

Why should it be complained? I know a lot of the same cases that may be applied.

пятница, 19 февраля 2016 г., 15:00:12 UTC+2 пользователь Eddilbert Macharia написал:

[Eddilbert Macharia]

Hello vadim when would such a relationship be needed I'm curious

[Tim Chase]

On 2016-02-19 07:29, Eddilbert Macharia wrote:
> Hello vadim when would such a relationship be needed I'm curious

Think of a hierarchy at a company. Most employees have a
supervisor. So your table would reference the supervisor in the same
table:

class Employee(models.Model):
name = ...
# ...
supervisor = models.ForeignKey("Employee")

You can then query for a person's manager, as well as use the
reverse relationship to find out the employees that a person manages.

-tkc

[Alex Heyden]

You would use it any time the relationship means something different. It would generally be inappropriate to use it as a simple backwards relationship (Django does this for you), but there's no reason not to have multiple relationships in a number of directions. In an HR system, someone could be both my beneficiary and my employee. 

On Fri, Feb 19, 2016 at 9:29 AM, Eddilbert Macharia <edd....@gmail.com> wrote:

Hello vadim when would such a relationship be needed I'm curious

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