Need suggestions for building many models with the same fields approximately

[cehceh]

Hi everyone,
I need your opinions about my models to build good and robust models by django.
I have the following models

# make a generic model 
class BasicData(models.Model):
    user = models.ForeignKey(
        "users.CustomUser",
        on_delete=models.CASCADE
    )

    active = models.BooleanField(default=False)

    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    is_deleted = models.BooleanField(default=False, verbose_name=_('Deleted'))
    deleted_at = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True


class CreateObject(BasicData):
    name = models.CharField(verbose_name="Name", max_length=100)
    type = models.CharField(verbose_name="Type", max_length=100, choices=OBJECT_TYPE)
    account_no = models.CharField(
                  verbose_name="Account No.", 
                  max_length=100, 
                  blank=True, null=True
     )
     updated_user = models.ForeignKey(
            "users.CustomUser", 
            related_name="user_make_create_object_changes", 
            on_delete=models.CASCADE
    )

    class Meta:
        verbose_name = _("create object")
        verbose_name_plural = _("Create Object")
        indexes = [
            models.Index(fields=["name"]),
            models.Index(fields=["type"]),
            models.Index(fields=["account_no"]),
            models.Index(fields=["active"]),
            models.Index(fields=["created_at"]),
            models.Index(fields=["updated_at"]),
            models.Index(fields=["is_deleted"]),
            models.Index(fields=["deleted_at"]),
        ]

    def __str__(self):
        return f"{self.name} - {self.type}"

I tended to use (CreateObject model) to build any model has the same fields(to reduce models coding), but I like to ask first in order to ensure that I have a robust models design.
- Here I have some questions (if I made the index for(active, create_at, updated_at, is_deleted and deleted_at)) in (BasicData) under class Meta:
- Will it apply in all models which inherit from (BasicData) and I don’t need to write it again and again in all models?

---

The next models have the same fields and I have others.

class UnitNames(BasicData):
    name = models.CharField(max_length=100)

    updated_user = models.ForeignKey(
        "users.CustomUser",
        related_name="user_make_unit_names_changes",
        on_delete=models.CASCADE,
    )

    class Meta:
        app_label = "configurations"
        verbose_name = "unit_names"
        verbose_name_plural = "UnitNames"
        indexes = [
            models.Index(fields=["name"]),
            models.Index(fields=["active"]),
            models.Index(fields=["created_at"]),
            models.Index(fields=["updated_at"]),
            models.Index(fields=["is_deleted"]),
            models.Index(fields=["deleted_at"]),
        ]

    def __str__(self):
        return "{}".format(self.name)  


class Branches(BasicData):
    name = models.CharField(max_length=100, unique=True)
    description = models.TextField(blank=True, null=True)

    updated_user = models.ForeignKey(
        "users.CustomUser",
        related_name="user_make_branches_changes",
        on_delete=models.CASCADE,
    )

    class Meta:
        app_label = "configurations"
        verbose_name = "branches"
        verbose_name_plural = "Branches"
        indexes = [
            models.Index(fields=["name"]),
            models.Index(fields=["active"]),
            models.Index(fields=["created_at"]),
            models.Index(fields=["updated_at"]),
            models.Index(fields=["is_deleted"]),
            models.Index(fields=["deleted_at"]),
        ]

    def __str__(self):
        return f"{self.name}"


class PosStation(BasicData):
    branch = models.ForeignKey(
        Branches,
        related_name="pos_branch",
        verbose_name=_("Branch"),
        on_delete=models.CASCADE,
    )
    name = models.CharField(max_length=100, unique=True, default="Text")
    description = models.TextField(blank=True, null=True, default="Text")

    updated_user = models.ForeignKey(
        "users.CustomUser",
        related_name="user_make_pos_station_changes",
        on_delete=models.CASCADE,
    )

    class Meta:
        app_label = "configurations"
        verbose_name = "pos_station"
        verbose_name_plural = "PosStations"
        ordering = ["-id"]
        indexes = [
            models.Index(fields=["name"]),
            models.Index(fields=["active"]),
            models.Index(fields=["created_at"]),
            models.Index(fields=["updated_at"]),
            models.Index(fields=["is_deleted"]),
            models.Index(fields=["deleted_at"]),
        ]

    def __str__(self):
        return f"{self.name}"


class Departments(BasicData):
    name = models.CharField(max_length=100)

    updated_user = models.ForeignKey(
        "users.CustomUser",
        related_name="user_make_departments_changes",
        on_delete=models.CASCADE,
    )

    class Meta:
        app_label = "configurations"
        verbose_name = "departments"
        verbose_name_plural = "Departments"
        indexes = [
            models.Index(fields=["name"]),
            models.Index(fields=["active"]),
            models.Index(fields=["created_at"]),
            models.Index(fields=["updated_at"]),
            models.Index(fields=["is_deleted"]),
            models.Index(fields=["deleted_at"]),
        ]

    def __str__(self):
        return f"{self.name}" 

Kindly if you have any suggestions to enhance my models, I will appreciate it
Thanks,

[Rigo-Villalta]

I think your design is OK. An abstract Models is a Python Class, so every model based in an abstract class will heritage all its methods and properties.

[KenWhitesell]

See the docs for Abstract base classes for the implications of class inheritance with regards to the Meta class.

Side note: You may also want to consider whether you really need indexes on all those fields for all tables.

[cehceh]

Thanks for your replys (@Rigo-Villalta and @KenWhitesell)
**I mean that if I can do as the following: Is it possible to add the index in the class Meta in “BasicData”

class BasicData(models.Model):
    user = models.ForeignKey(
        "users.CustomUser",
        on_delete=models.CASCADE
    )

    active = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    is_deleted = models.BooleanField(default=False, verbose_name=_('Deleted'))
    deleted_at = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True
        indexes = [
            models.Index(fields=["active"]),
            models.Index(fields=["created_at"]),
            models.Index(fields=["updated_at"]),
            models.Index(fields=["is_deleted"]),
            models.Index(fields=["deleted_at"]),
        ]

**And the second inquiry is Can I use ONE model (CreateObject) instead of building (UnitNames, PosStation, Branches and Departments)

I will give an example:
Using of (UnitNames) model: is for adding measuring unit name like(kilogram, meter, liter and so on)
Using of (Branches) model: is for adding branch name like(New York branch and so on)

Using of (Department) model: is for adding department name like(IT department, Purchasing department and so on)

**Is it possible and Is it a good way to make (CreateObject) model to perform the mission of all these models by select only the type ?
(i.e I want to use “CreateObject” and choose the type (UNIT) from (choices=OBJECT_TYPE) to create the unit name instead of using “UnitNames” and choose type(BRANCH) from (choices=OBJECT_TYPE))

BANK = "bank"
UNIT = "unit"
BRANCH = "branch"
DEPARTMENT = "department"
CREDIT_CARD = "visa"
SAFE = "safe"

OBJECT_TYPE = (
    (BANK, "Bank"),
    (UNIT, "Unit"),
    (BRANCH, "Branch"),
    (DEPARTMENT, "Department"),
    (CREDIT_CARD, "Visa"),
    (SAFE, "Safe"),
)

Hope my inquiry is clear now.
Thanks

[KenWhitesell]

First a side note: Please do not bold large chunks of your text. It makes it very difficult to read.

@cehceh

I mean that if I can do as the following: Is it possible to add the index in the class Meta in “BasicData”

That is answered by the docs referenced in my previous response.

@cehceh

Is it possible and Is it a good way to make (CreateObject) model to perform the mission of all these models by select only the type ?

Is it possble? Yes.

Is it a good way? Absolutely not.

As an abstract model, you shouldn’t be thinking of BasicData as if it were a model. You should be thinking of it as a template that you will use and extend in your “real” models.

You could also implement this BasicData as a mixin model as well, but I’m not sure it really provides any benefit in your case. (For an example of model mixins, see Model Extensions — django-extensions 3.2.3 documentation)

[cehceh]

@KenWhitesell

Is it a good way? Absolutely not.

That’s exactly what I want to hear (I prefer to make separated model for them)

@KenWhitesell

That is answered by the docs referenced in my previous response.

Thanks it’s helpful .

As I get help here and found awesome people give advices and help, So I will open another inquiries to understand and learn

Thanks @KenWhitesell so much

[cehceh]

Please @KenWhitesell how can I mark your answer as a solution to my issue. I didn’t found a (Solution button)
Thanks again (@KenWhitesell , @Rigo-Villalta )

[KenWhitesell]

I have asked the Admins about this - I’ll let you know what I find out.

[KenWhitesell]

I have been told that this has now been made available. Please check and let me know.