CODEWITHSUNDEEP
pythondjangodjango-models
Masterbuilder
Masterbuilder

Reputation: 509

Django model relationship with circular relationship

I am new to Django and trying to understand the model relationships, here is my use case:

I have a Creator object which can create multiple Listing under a Category. Category can have multiple Listings from multiple Creators.

Creator -- Creates a Listing about a service -- under a Category or multiple Category

I am trying to find the thought process behind picking the correct relationship while defining this kind circular relationship. Which one of the model should go first? Is it Category which is first and Creator second and Listing at the end, is Creator, Category and Listing all belong to a Many to Many relationship, if then how are they linked?

Upvotes: 1

Views: 265

Answers (2)

Amandeep Singh
Amandeep Singh

Reputation: 521

In Django Models there are three types of relationships.

one to one - when one entity is unique to other entity Example: A user model can be in one to one relationship to customer model. Every customer is unique user

many to many - When one entity can has relationship with many other entities and vice versa. Example : pizza and toppings, pizza can have many toppings, and same topping can be applied on various pizza

one to many - also called foreign key in Django when a single entity is related to many other entities but vice versa is not true.

Example: your Use case applies here. A creator can create multiple listings but a single listing can be mapped to single creator only, not multiple creator.

Upvotes: -1

Selcuk
Selcuk

Reputation: 59164

You don't have a circular relationship, this should cover your use case:

class Creator:
    ...


class Category:
    ...


class Listing:
    creator = models.ForeignKey(Creator, on_delete=models.PROTECT)
    category = models.ManyToMany(Category)

I am assuming that a Listing can be under multiple Categorys. If each listing can only have one Category, the second (category) relation must be a ForeignKey too.

Upvotes: 2

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