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Purpose

• It takes a tuple or list containing the names of fields you want to exclude.
• The exclude attribute of ModelAdmin is used to hide specific fields from the Django admin interface when editing or creating model instances.

How it Works

1. Registration
   When you register a model with the admin using admin.site.register(MyModel, MyModelAdmin), Django considers the exclude attribute in MyModelAdmin.
2. Field Listing
   The admin interface uses the exclude list to filter out the specified fields from the default set of fields for your model.
3. Hidden Fields
   The excluded fields are no longer displayed in the admin forms for creating, editing, or viewing model instances.

Example

from django.contrib import admin
from .models import Book

class BookAdmin(admin.ModelAdmin):
    exclude = ('slug',)  # Exclude the 'slug' field from the admin interface

admin.site.register(Book, BookAdmin)

In this example, the slug field will be hidden from the admin forms for creating, editing, and viewing Book instances.

Important Points

• exclude is primarily for controlling the display of fields in the admin interface. It doesn't affect database access or manipulation.
• Consider using readonly_fields to make fields read-only instead of hiding them completely, if appropriate.
• exclude has higher precedence than fields in ModelAdmin. If you specify a field in both exclude and fields, it will be excluded.

• Conditional logic
  Use conditional logic within your admin templates to hide fields based on specific scenarios.
• get_fields() method
  Override this method in your ModelAdmin class to dynamically determine which fields to exclude based on specific conditions.

---

Excluding Multiple Fields

class ProductAdmin(admin.ModelAdmin):
    exclude = ('description', 'created_at')  # Exclude 'description' and 'created_at' fields

Dynamic Exclusion with get_fields()

from django.contrib import admin

class ArticleAdmin(admin.ModelAdmin):
    def get_fields(self, request, obj=None):
        fields = super().get_fields(request, obj)
        if obj:  # Only exclude 'author' when editing existing articles
            fields = [f for f in fields if f != 'author']
        return fields

admin.site.register(Article, ArticleAdmin)

Using readonly_fields for Read-Only Fields

class OrderAdmin(admin.ModelAdmin):
    exclude = ('created_at',)  # Exclude 'created_at' but keep it read-only
    readonly_fields = ('total_price',)  # Make 'total_price' read-only

admin.site.register(Order, OrderAdmin)

Conditional Exclusion with Template Logic

(This example requires modifying your admin templates)

{% if request.user.is_superuser %}
  {{ form.title }}  {% endif %}

---

get_fields() method

• You can access information like the current user, the instance being edited (if any), and use them to control the displayed fields.
• This method allows you to dynamically determine which fields to include or exclude based on specific conditions.
• Override the get_fields() method in your ModelAdmin class.

from django.contrib import admin

class ProductAdmin(admin.ModelAdmin):
    def get_fields(self, request, obj=None):
        fields = super().get_fields(request, obj)  # Get default fields
        if not request.user.is_staff:  # Exclude 'wholesale_price' for non-staff users
            fields = [f for f in fields if f != 'wholesale_price']
        return fields

admin.site.register(Product, ProductAdmin)

Custom ModelForm

• Set the form attribute of your ModelAdmin class to your custom form.
• Define the fields or exclude attributes in the Meta class of your form to control which fields are included.
• Create a custom ModelForm subclass for your model.

from django import forms
from .models import User

class UserForm(forms.ModelForm):
    class Meta:
        model = User
        exclude = ('password',)  # Exclude password field

class UserAdmin(admin.ModelAdmin):
    form = UserForm

admin.site.register(User, UserAdmin)

Fieldsets

• This allows you to create a more organized layout for the admin interface without completely hiding fields.
• You can define which fields belong to each fieldset.
• Use fieldsets in your ModelAdmin class to group related fields together.

class ArticleAdmin(admin.ModelAdmin):
    fieldsets = (
        ('Basic Information', {
            'fields': ('title', 'slug'),
        }),
        ('Content', {
            'fields': ('content',),
        }),
    )

admin.site.register(Article, ArticleAdmin)

Template Logic (Conditional Visibility)

• You can use Django template tags like {% if %} to conditionally display or hide fields based on various factors.
• This approach involves modifying your admin templates.

{{ form.description }}  {% if show_description %}
  {{ form.description }}
{% endif %}

• Template Logic: Offers fine-grained control over field visibility based on custom conditions.
• Fieldsets: Great for organizing related fields and improving the admin interface layout.
• Custom ModelForm: Useful for global field control or specific logic within the form itself.
• get_fields(): Ideal for dynamic exclusion based on request context or object state.