Home  >  Article  >  Database  >  How to Handle Foreign Key Relationships with Models in Different Databases in Django?

How to Handle Foreign Key Relationships with Models in Different Databases in Django?

Barbara Streisand
Barbara StreisandOriginal
2024-10-29 19:59:02161browse

How to Handle Foreign Key Relationships with Models in Different Databases in Django?

Foreign Key and Cross-Database Constraints

When working with Django models stored in different databases, a common issue arises with foreign keys. For example, consider the following:

class LinkModel(models.Model): # in 'urls' database</p>
<pre class="brush:php;toolbar:false">id = models.AutoField(primary_key=True)
host_id = models.IntegerField()
path = models.CharField(max_length=255)

class NewsModel(models.Model): # in default database

id = models.AutoField(primary_key=True)
title = models.CharField(max_length=50)
link = models.ForeignKey(LinkModel)

Upon attempting to assign a foreign key to a model from a different database, an error will be raised:

Cannot assign "<LinkModel: />": instance is on database "default", value is on database "urls"<br>

This occurs because Django does not currently support cross-database foreign key relationships. All foreign key relationships must be defined within a single database.

Overcoming the Limitation

To resolve this issue, you can either create a router to explicitly route your models to specific databases or consider using a relational database management system (RDBMS) that supports cross-database relationships. Currently, Django does not provide an out-of-the-box solution for such relationships.

Alternatively, you can try applying a patch to the ForeignKey() class to address this issue, as described in the linked ticket.

The above is the detailed content of How to Handle Foreign Key Relationships with Models in Different Databases in Django?. For more information, please follow other related articles on the PHP Chinese website!

Statement:
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn