Django admin - 编辑页面上的错误模型对象

Question

I have 3 inherited classes (Fitters -> Workers -> Staffs) connected with tables in my Database (class names in the plural, but that's not important now).

User can add/edit/remove only Fitters. The Workers and Staffs tables are updated automatically (cascaded).

It works fine: when I add new Fitter, all changes come to all tables in database. But when I want to edit any Fitter via Django admin tool, I go to edit Fitter page and I see incorrectly filled fields.

For example:

• In Staffs table I have "John Smith" with id=41
• In Workers table I have the record with id=21 and ForeignKey=41 (to John Smith)
• In Fitters table I have the record with id=5 and ForeignKey=21 (to record in Workers table)

When I go to edit Fitter "John Smith" page, I see all fields filled by "Kevin Thomas" (id=21 in Staffs table!). So, Django misses the Workers table and goes directly to the Staffs table.

How can I fix it?

Here is my draft code:

class Staffs(models.Model):
    id = models.AutoField(primary_key=True)

    name = models.CharField(max_length=135, blank=True)
    surname = models.CharField(max_length=135, blank=True)

    def __unicode__(self):
        return self.name + " " + self.surname

    class Meta:
        db_table = u'staffs'

class Workers(Staffs):
    idWorker = models.AutoField(primary_key=True, db_column='id')

    staffs_idstaff = models.OneToOneField('Staffs', db_column='Staffs_idstaff', parent_link=True)
    brigades_idbrigade = models.ForeignKey('Brigades', db_column='Brigades_idBrigade')

    def __unicode__(self):
        return self.staffs_idstaff.name + " " + self.staffs_idstaff.surname

    class Meta:
        db_table = u'workers'

class Fitters(Workers):
    idFitter = models.AutoField(primary_key=True, db_column='id')

    qualification = models.CharField(max_length=135, blank=True)
    workers_idworker = models.OneToOneField('Workers', db_column='Workers_idWorker', parent_link=True)

    def __unicode__(self):
        staff = self.workers_idworker.staffs_idstaff
        return staff.name + " " + staff.surname

    class Meta:
        db_table = u'fitters'

EDIT1:

I tried to change my code like this:

class Staffs(models.Model):
    id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=135, blank=True)
    surname = models.CharField(max_length=135, blank=True)

    class Meta:
        db_table = u'staffs'

class Workers(Staffs):
    idWorker = models.AutoField(primary_key=True)
    brigades_idbrigade = models.ForeignKey('Brigades')

    class Meta:
        db_table = u'workers'

class Fitters(Workers):
    idFitter = models.AutoField(primary_key=True)
    qualification = models.CharField(max_length=135, blank=True)

    class Meta:
        db_table = u'fitters'

It's pretty simple now. I synced my database, but I have the absolutely same problem!

EDIT2:

Part of my admin.py file:

from django.contrib import admin
from appclient.models import *

admin.site.register(Fitters)
admin.site.register(Staffs)
admin.site.register(Workers)
...

SOLUTION:

Solution is I don't need use my own id's and ForeignKey's for each model. Djando automatically creates special field for each model and uses it as an id (PrimaryKey) and for link to the parent tables (ForeignKey).

Here is solution:

class Staffs(models.Model):
    name = models.CharField(max_length=135, blank=True)
    surname = models.CharField(max_length=135, blank=True)

    class Meta:
        db_table = u'staffs'

class Workers(Staffs):
    brigades_idbrigade = models.ForeignKey('Brigades')

    class Meta:
        db_table = u'workers'

class Fitters(Workers):
    qualification = models.CharField(max_length=135, blank=True)

    class Meta:
        db_table = u'fitters'

Thanks to everyone who helped me.

Answer 1

This does seem somewhat strange. However, as far as I understand, Django will automatically setup the required one-to-one mappings between parents and children, when using multi-table inheritance . As you have also set these up manually, it might very well be that some kind of inconsistency is introduced due this.

If you take a look directly in the database, are the two different one-to-one relations consistent?

What happens if you remove the explicit one-to-one fields from your models?