Error when setting table_name with inherit=True

[muneeb706]

Problem Statement

When table_name is set with inherit=True in base model then error is thrown when makemigrations command is entered.

For example:

from django.db import models
from simple_history.models import HistoricalRecords

class BaseModel(models.Model):
    created_date = models.DateTimeField(auto_now_add=True)
    last_updated_date = models.DateTimeField(auto_now=True)
    history = HistoricalRecords(inherit=True, table_name='base_model_history')
  
class ChildModel(BaseModel):
    title = models.CharField(max_length=255, blank=False, null=False)

Following error is thrown with above code:

(models.E028) db_table 'base_model_history' is used by multiple models: inherit.HistoricalBaseModel, inherit.HistoricalChildModel.

Describe the solution you'd like

Cause of Problem

As per my understanding, after looking at the source code, I found that Meta.db_table property of model is updated when table_name property is set. In case, when inherit=True, self.table_name still points to table_name set in the base model when create_history_model method is invoked for the child model. This logic is implemented in line 301-302 in create_history_model method.

Possible Solution

inherited flag is sent as an argument to create_history_model method, this can be used in the condition where table_name is checked. Condition at line 301 will look like this:
if not inherited and self.table_name is not None:

If it can not be done, then this behavior should be mentioned explicitly in the documentation.

Describe alternatives you've considered

Overridden create_history_model method to update table_name when inherited is set to True and table_name is set:

from django.db import models
from simple_history.models import HistoricalRecords


class CustomHistoricalRecords(HistoricalRecords):
    def create_history_model(self, model, inherited):
        if inherited and self.table_name:
            self.table_name=f"{model._meta.app_label}_{self.get_history_model_name(model)}"
        history_model = super().create_history_model(model, inherited)
        return history_model

class BaseModel(models.Model):
    created_date = models.DateTimeField(auto_now_add=True)
    last_updated_date = models.DateTimeField(auto_now=True)
    history = CustomHistoricalRecords(inherit=True, table_name="base_model_history")
  
class ChildModel(BaseModel):
    title = models.CharField(max_length=255, blank=False, null=False)

Additional context

I found this issue while looking for the solution of #1174