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Changes between Version 1 and Version 2 of Ticket #35129, comment 4

-              v1
+              v2
 Under the hood `ForeignKey` is `Field` + `ForeignObject` + the equivalent of a `ForeignKeyConstraint(ForeignObject)` entry in `Model._meta.constraints` so if you care about the ORM + JOIN generation part and don't want a database constraint it's likely what you're looking for.
+In other words, doing
+{{{#!python
+class Journal(Model):
+    issn = models.CharField(max_length=9, primary_key=True)
+    name = models.CharField(max_length=255)
+class Biblio(Model):
+    journal = models.ForeignKey(Journal, models.ON_DELETE, null=True)
+}}}
+Is roughly the sugared equivalent of doing
+{{{#!python
+class Journal(Model):
+    issn = models.CharField(max_length=9, primary_key=True)
+    name = models.CharField(max_length=255)
+class Biblio(Model):
+    issn = models.CharField(max_length=50, null=True, db_index=True)
+    journal = models.ForeignObject(
+        Journal,
+        models.ON_DELETE,
+        from_fields=["issn"],
+        to_fields=["issn"],
+    )
+    class Meta:
+        constraints = [
+            ForeignKeyConstraint(Journal, from_fields=["issn"], to_fields=["issn"])  # XXX: This currently doesn't exist but it could
+        ]
+}}}