Unlocking Object Details in Django Admin Logs: Beyond object_id

Purpose

• It stores the primary key (ID) of the model object that was added, changed, or deleted through the Django admin interface.
• object_id is a field within the LogEntry model inside Django's admin application.

Relationship with ContentType

• Together, content_type and object_id uniquely identify the specific model object that was affected by an admin action.
• ContentType provides a generic way to represent different model types in Django's content framework.
• The LogEntry model also has a field called content_type, which is a foreign key to the ContentType model.

Example

• A LogEntry record will be created, with:
  • action_flag set to ADDITION (indicating an addition)
  • content_type referencing the ContentType for the BlogPost model
  • object_id containing the primary key value of the newly created blog post
• Imagine you create a new blog post through the Django admin.

Usage

• However, it's often more convenient to use LogEntry.content_type and object_id in conjunction to construct the full URL for viewing or editing the object in the admin interface using reverse(). This approach ensures compatibility across different model types.
• You can access object_id from a LogEntry instance to retrieve the ID of the affected object.

from django.contrib.admin.models import LogEntry
from django.contrib.contenttypes.models import ContentType
from django.core.urlresolvers import reverse  # Assuming Django < 3.0

log_entry = LogEntry.objects.get(pk=1)  # Assuming you have a LogEntry instance
content_type = log_entry.content_type

# Construct the admin URL for the affected object
if content_type and log_entry.object_id:
    url_name = "admin:%s_%s_change" % (content_type.app_label, content_type.model)
    try:
        object_url = reverse(url_name, args=(log_entry.object_id,))
    except NoReverseMatch:
        pass  # Handle cases where the URL pattern doesn't exist

• While you can access object_id directly, using content_type and reverse() is generally recommended for better flexibility and error handling.
• object_id is a text field because it might contain different data types depending on the model's primary key field (e.g., integer for AutoField, UUID for UUIDField).

---

Filtering Log Entries by Object ID

from django.contrib.admin.models import LogEntry

# Get all log entries related to a specific object (e.g., a blog post with ID 10)
object_id = 10
log_entries = LogEntry.objects.filter(object_id=object_id)

for entry in log_entries:
    print(f"Action: {entry.action_flag}, Object: {entry.object_repr}")

Custom Admin View with LogEntry Information

from django.contrib.admin.models import LogEntry
from django.contrib.admin.views.decorators import staff_member_required
from django.shortcuts import render

@staff_member_required
def custom_admin_view(request, object_id, model_name):
    # Retrieve the object based on model_name and object_id
    # (This would typically involve using a model manager or querying the specific model)
    obj = None  # Replace with actual object retrieval logic

    # Get related log entries
    log_entries = LogEntry.objects.filter(content_type__model=model_name, object_id=object_id)

    context = {
        'object': obj,
        'log_entries': log_entries,
    }

    return render(request, 'custom_admin_view.html', context)

from django.contrib.admin.models import LogEntry
from django.contrib.contenttypes.models import ContentType
from django.contrib.admin import ModelAdmin

class MyModelAdmin(ModelAdmin):
    def get_queryset(self, request):
        qs = super().get_queryset(request)
        return qs.select_related('content_type')  # Pre-fetch ContentType for efficiency

    def has_view_permission(self, request, obj=None):
        # Customize view permission based on object_id or content_type (optional)
        return super().has_view_permission(request, obj)

    def has_delete_permission(self, request, obj=None):
        # Customize delete permission based on object_id or content_type (optional)
        return super().has_delete_permission(request, obj)

    def get_object_repr(self, obj):
        # Customize object representation for display within LogEntry
        content_type = obj.content_type
        if content_type and obj.object_id:
            return f"{content_type.app_label}.{content_type.model} ({obj.object_id})"
        return super().get_object_repr(obj)

---

Leverage content_type and Model Access

• content_type provides the model information, while you can use the model's manager or queryset methods to retrieve the specific object based on the object_id.
• The combined power of content_type and your model's manager or queryset methods can often achieve a similar outcome as using object_id.

Example

from django.contrib.admin.models import LogEntry
from django.contrib.contenttypes.models import ContentType
from your_app.models import YourModel

log_entry = LogEntry.objects.get(pk=1)  # Assuming you have a LogEntry instance
content_type = log_entry.content_type

# Retrieve the affected object using content_type and model-specific methods
if content_type and log_entry.object_id:
    model_class = content_type.model_class()
    affected_object = model_class.objects.get(pk=log_entry.object_id)

Custom Fields or Signals

• Custom fields within the model itself would be directly accessible for each object, while signals could be used to capture additional data or perform actions when changes occur.
• If you need more specific information beyond the primary key for tracking purposes, consider adding custom fields to your models or using Django signals.

Example (Custom Field)

from django.db import models

class YourModel(models.Model):
    name = models.CharField(max_length=100)
    custom_tracking_id = models.CharField(max_length=255, blank=True)

    def save(self, *args, **kwargs):
        # Generate or update custom_tracking_id as needed
        super().save(*args, **kwargs)

from django.db.models.signals import post_save, post_delete
from django.dispatch import receiver
from your_app.models import YourModel

@receiver(post_save, sender=YourModel)
def track_model_save(sender, instance, created, **kwargs):
    if created:
        # Perform actions or store additional data when a new object is saved

@receiver(post_delete, sender=YourModel)
def track_model_delete(sender, instance, **kwargs):
    # Perform actions or store data when an object is deleted