Advanced Django Admin: Inlines, Actions, and Custom Admin Views

# Inline Editing
from django.contrib import admin
from .models import Post, Comment, Image

# Tabular inline (table format)
class CommentInline(admin.TabularInline):
    model = Comment
    extra = 1  # Number of empty forms
    fields = ['author', 'text', 'approved']
    readonly_fields = ['created_at']

# Stacked inline (full form format)
class ImageInline(admin.StackedInline):
    model = Image
    extra = 0
    max_num = 5  # Maximum number of inlines
    min_num = 1  # Minimum number required
    fields = ['image', 'caption', 'order']

@admin.register(Post)
class PostAdmin(admin.ModelAdmin):
    inlines = [CommentInline, ImageInline]
    list_display = ['title', 'author', 'published_date']

# Advanced inline configuration
class CommentInline(admin.TabularInline):
    model = Comment
    extra = 1
    can_delete = True  # Allow deletion
    show_change_link = True  # Link to full edit page
    
    # Customize queryset
    def get_queryset(self, request):
        qs = super().get_queryset(request)
        return qs.filter(approved=True)
    
    # Conditional readonly fields
    def get_readonly_fields(self, request, obj=None):
        if obj and obj.is_published:
            return ['author', 'text']
        return []

# Inline with custom form
from django import forms

class CommentInlineForm(forms.ModelForm):
    class Meta:
        model = Comment
        fields = '__all__'
    
    def clean_text(self):
        text = self.cleaned_data['text']
        if len(text) < 10:
            raise forms.ValidationError('Comment too short')
        return text

class CommentInline(admin.TabularInline):
    model = Comment
    form = CommentInlineForm

# Generic inline (for generic relations)
from django.contrib.contenttypes.admin import GenericTabularInline
from .models import Tag

class TagInline(GenericTabularInline):
    model = Tag
    extra = 1

# Custom Admin Actions
from django.contrib import admin
from django.utils import timezone

@admin.register(Post)
class PostAdmin(admin.ModelAdmin):
    list_display = ['title', 'status', 'published_date']
    actions = ['make_published', 'make_draft', 'export_as_csv']
    
    # Action method
    @admin.action(description='Publish selected posts')
    def make_published(self, request, queryset):
        updated = queryset.update(
            status='published',
            published_date=timezone.now()
        )
        self.message_user(request, f'{updated} posts published successfully.')
    
    @admin.action(description='Move to draft')
    def make_draft(self, request, queryset):
        queryset.update(status='draft')
        self.message_user(request, 'Selected posts moved to draft.')
    
    # Action with confirmation
    @admin.action(description='Delete with confirmation')
    def delete_with_warning(self, request, queryset):
        count = queryset.count()
        if count > 10:
            self.message_user(
                request,
                f'Cannot delete more than 10 posts at once',
                level='error'
            )
            return
        queryset.delete()
        self.message_user(request, f'{count} posts deleted')
    
    # Export action
    import csv
    from django.http import HttpResponse
    
    @admin.action(description='Export to CSV')
    def export_as_csv(self, request, queryset):
        response = HttpResponse(content_type='text/csv')
        response['Content-Disposition'] = 'attachment; filename="posts.csv"'
        
        writer = csv.writer(response)
        writer.writerow(['ID', 'Title', 'Status', 'Author', 'Views'])
        
        for post in queryset:
            writer.writerow([
                post.id,
                post.title,
                post.status,
                post.author.username,
                post.views
            ])
        
        return response

# Action with intermediate page
from django.shortcuts import render

@admin.action(description='Send notification')
def send_notification(modeladmin, request, queryset):
    if 'apply' in request.POST:
        message = request.POST.get('message')
        for post in queryset:
            # Send notification
            send_email(post.author.email, message)
        modeladmin.message_user(request, f'Sent to {queryset.count()} authors')
        return
    
    return render(request, 'admin/send_notification.html', {
        'posts': queryset,
        'action': 'send_notification'
    })

# Disable default delete action
@admin.register(Post)
class PostAdmin(admin.ModelAdmin):
    def get_actions(self, request):
        actions = super().get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions

# Custom Admin Views
from django.contrib import admin
from django.urls import path
from django.shortcuts import render
from django.http import HttpResponse

@admin.register(Post)
class PostAdmin(admin.ModelAdmin):
    change_list_template = 'admin/post_changelist.html'
    
    def get_urls(self):
        urls = super().get_urls()
        custom_urls = [
            path('statistics/', self.admin_site.admin_view(self.statistics_view), name='post_statistics'),
            path('import/', self.admin_site.admin_view(self.import_view), name='post_import'),
            path('export/', self.admin_site.admin_view(self.export_view), name='post_export'),
        ]
        return custom_urls + urls
    
    def statistics_view(self, request):
        from django.db.models import Count, Avg, Sum
        
        stats = {
            'total_posts': Post.objects.count(),
            'published': Post.objects.filter(status='published').count(),
            'drafts': Post.objects.filter(status='draft').count(),
            'avg_views': Post.objects.aggregate(Avg('views'))['views__avg'],
            'total_views': Post.objects.aggregate(Sum('views'))['views__sum'],
            'by_author': Post.objects.values('author__username').annotate(count=Count('id')),
        }
        
        context = {
            **self.admin_site.each_context(request),
            'title': 'Post Statistics',
            'stats': stats,
        }
        return render(request, 'admin/post_statistics.html', context)
    
    def import_view(self, request):
        if request.method == 'POST':
            csv_file = request.FILES['file']
            # Process CSV import
            import csv
            reader = csv.reader(csv_file.read().decode('utf-8').splitlines())
            next(reader)  # Skip header
            
            imported = 0
            for row in reader:
                Post.objects.create(
                    title=row[0],
                    content=row[1],
                    author_id=row[2]
                )
                imported += 1
            
            self.message_user(request, f'Imported {imported} posts')
            return redirect('..')
        
        context = {
            **self.admin_site.each_context(request),
            'title': 'Import Posts',
        }
        return render(request, 'admin/post_import.html', context)
    
    def export_view(self, request):
        import csv
        response = HttpResponse(content_type='text/csv')
        response['Content-Disposition'] = 'attachment; filename="posts_export.csv"'
        
        writer = csv.writer(response)
        writer.writerow(['ID', 'Title', 'Content', 'Author', 'Status', 'Views'])
        
        for post in Post.objects.all():
            writer.writerow([
                post.id,
                post.title,
                post.content,
                post.author.username,
                post.status,
                post.views
            ])
        
        return response

# Custom dashboard
class MyAdminSite(admin.AdminSite):
    site_header = 'My Admin'
    
    def get_urls(self):
        urls = super().get_urls()
        custom_urls = [
            path('dashboard/', self.admin_view(self.dashboard_view), name='dashboard'),
        ]
        return custom_urls + urls
    
    def dashboard_view(self, request):
        context = {
            **self.each_context(request),
            'title': 'Dashboard',
            'recent_posts': Post.objects.order_by('-created_at')[:10],
        }
        return render(request, 'admin/dashboard.html', context)

# Template: admin/post_changelist.html
# {% extends "admin/change_list.html" %}
# {% block object-tools-items %}
#   {{ block.super }}
#   <li>
#     <a href="{% url 'admin:post_statistics' %}" class="button">Statistics</a>
#   </li>
#   <li>
#     <a href="{% url 'admin:post_import' %}" class="button">Import</a>
#   </li>
#   <li>
#     <a href="{% url 'admin:post_export' %}" class="button">Export</a>
#   </li>
# {% endblock %}