I have a table for users and another for what I call ‘documents’ in my database (I use postgresql). That last one has a ‘user/author’ column as a foreign key. How can I set a sequential index column for each user/author? Here’s what’s on my mind:
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user1fills the table with 10 rows, then that column varies from 1 up to 10. -
user2fills the same table with 5 more items. For thoseuser2’s rows that same column varies from 1 up to 5. -
If any row of a user gets deleted, that column (for that user’s data) gets “re-indexed”, i.e., if
user2deletes the 3rd entry, the former 4th gets re-indexed to 3, and the former 5th to 4.
How I came up with this problem?
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I want to use that column as an index in the url’s model-view. I could use a uuid key instead, but I find, for example,
myapp.com/edit/1,myapp.com/edit/2and so on more organized. -
Currently I perform the above described actions at view level: every time a row gets deleted all rows for that user gets re-indexed; every time a new row gets added, it’s index is set. The problem is that I feel that this shouldn’t be the role of a view.
So, what I want is to set a sequential index (positive integer) column unique only for each user/author at model’s level. Meaning: is there’s a field in Django models that can perform that action? Is there’s a similar alternative?
Here’s a very simple idea of the described parts of my app:
# apps/accounts/models.py
from django.contrib.auth.models import AbstractUser
from django.contrib.auth.models import PermissionsMixin
from django.db import models
class CustomUser:
email = models.EmailField(unique=True, null=False, blanck=True)
# apps/documents/models.py
from django.db import models
from accounts.models import CustomUser
class Document(models.Model):
author = models.ForeignKey(CustomUser, on_delete=models.CASCADE)
subject = models.CharField(max_length=64)
content = models.TextField()
that_index_I_described = models.IntegerField(default=0)
# apps/documents/views.py
from django.views.generic import CreateView
from django.views.generic import ListView
from django.views.generic import DeleteView
from django.urls import reverse_lazy
def reindex_documents(author):
# access, count rows, reindex if needed
return number_of_rows_for_author
class CreateDocuemnt(CreateView):
# login and passes mixins, validations and stuffs
exam.that_index_I_described = reindex_documents(self.author) + 1
exam.save()
class ViewDocuments(ListView):
# login and passes mixins
# queryset = all user's documents
class DeleteDocument(DeleteView):
# login and passes mixins
def get_url_success(self,):
reindex_documents(self.author)
return reverse_lazy('list-view')