Question

How can I integrate m2m fields into modelAdmin, considering that this field has through argument and that I can’t change the DB? Or how can I use inlinetabular admin with add more button?

Description

I have Django 5 app working with legacy DB (PostgreSQL).

This DB has 3 tables described by models bellow:

class EmployeeLinkRole(models.Model):
    employee = models.ForeignKey(
        "Employees",
        models.DO_NOTHING,
        db_column="Employee_ID",
        primary_key=True,
    ) 
    role = models.ForeignKey("Roles", models.DO_NOTHING, db_column="Role_ID")

    class Meta:
        managed = False
        db_table = 'Timesheet"."Employee_Link_Role'
        unique_together = (("employee", "role"),)


class Employees(models.Model):
    employee_id = models.BigAutoField(
        db_column="Employee_ID", primary_key=True
    )
    employee_name = models.CharField(
        max_length=500, db_column="Employee_Name", blank=True, null=True
    )
    role = models.ManyToManyField(
        "Roles",
        through=EmployeeLinkRole,
        through_fields=("employee", "role"),
    )

    class Meta:
        managed = False
        db_table = 'Timesheet"."Employees'


class Roles(models.Model):
    role_id = models.AutoField(db_column="Role_ID", primary_key=True)
    role_name = models.CharField(max_length=500, db_column="Role_Name")

    class Meta:
        managed = False
        db_table = 'Timesheet"."Roles'

My admin code:

class RoleInline(admin.TabularInline):
    model = Employees.role.through


@admin.register(Employees)
class EmployeesAdmin(admin.ModelAdmin):
    inlines = [
        RoleInline,
    ]


@admin.register(Roles)
class RolesAdmin(admin.ModelAdmin):
    inlines = (RoleInline,)

Issue

The issue I am facing: inline model is show and work fine in both Employees and Roles models.
However I can’t make it to show “Add more” button in Employees admin.

In Employees

In Roles

Expectations

I need an “add more” button in my inlinetabular admin in both Employees and Roles admins.

What I checked

I’ve spent loads of time searching for a solution, including talking to GPT.

I’ve found out that the block with the button has “display: none” attribute.

I’ve already tried to add extra = 4 and max_num = 10 attributes to inline admin.

I’ve already tried to redefine save and has_changed methods of ModelAdmin class.

I’ve already tried to collectstatic.