Django multiple models, same table

Question

I have a legacy database, with a table that represents nodes in the filesystem. There are few types of nodes e.g. A, B, C and different types have different properties. In current database design there is one table that holds the information about a node. If the node is of type A then only fields relevant to the type A are set. Now I would like to express the types A, B, C as models. The problem that arises is:

1. I would like to have such behaviour, all the three types have a name property. I would like to filter all the nodes in the filesystem by name property and get a list of objects of good types.

2. Each node as a parent link, expressed as foreign key in the database, so probably some form of inheritance should take place.

Is it possible in django?

Answer 1

Yes, it is possible. Here is an example:

models.py

from django.db import models

# Create your models here.
class NodeA(models.Model):

    name_a = models.CharField(max_length=75, blank=True, null=True)

    class Meta:
        db_table = 'Nodes'
        managed = False

class NodeB(models.Model):

    name_b = models.CharField(max_length=75, blank=True, null=True)

    class Meta:
        db_table = 'Nodes'
        managed = False

class NodeC(models.Model):

    name_c = models.CharField(max_length=75, blank=True, null=True)

    class Meta:
        db_table = 'Nodes'
        managed = False

Database schema (SQLITE)

 Nodes {
    id        integer   primary key
    name_a    TEXT
    name_b    TEXT
    name_c    TEXT }

Proof of concept

import NodeA, NodeB, NodeC

a = NodeA()
a.name_a = 'Node A'
a.save()

b = NodeB()
b.name_b = 'Node B'
b.save()

c = NodeC()
c.name_c = 'Node C'
c.save()

This produces:

id        name_a        name_b        name_c
1         Node A
2                       Node B
3                                     Node C