django-approval-workflow 0.8.2

A powerful, flexible Django package for implementing dynamic multi-step approval workflows

Django Approval Workflow

A powerful, flexible, and reusable Django package for implementing dynamic multi-step approval workflows in your Django applications.

✨ Features

• 🚀 Simplified Interface: New developer-friendly advance_flow API that takes objects directly
• ⚙️ MIDDLEWARE-Style Configuration: Configure handlers in settings just like Django MIDDLEWARE
• 🔄 Dynamic Workflow Creation: Create approval workflows for any Django model using GenericForeignKey
• 👥 Multi-Step Approval Process: Support for sequential approval steps with role-based assignments
• 🎭 Role-Based Approvals: Three strategies (ANYONE, CONSENSUS, ROUND_ROBIN) for dynamic role-based approvals
• 🔐 Automatic Permission Validation: Built-in user authorization for both direct and role-based assignments
• 🔗 Role-Based Permissions: Hierarchical role support using MPTT (Modified Preorder Tree Traversal)
• ⚡ High-Performance Architecture: Enterprise-level optimizations with O(1) lookups and intelligent caching
• 📊 Repository Pattern: Centralized data access with single-query optimizations
• 🔄 Flexible Actions: Approve, reject, delegate, escalate, or request resubmission at any step
• 🎯 Enhanced Hook System: Before and after hooks for complete workflow lifecycle control
• 🧩 Custom Fields Support: Extensible extra_fields JSONField for custom data without package modifications
• ⏰ SLA Tracking: Built-in SLA duration tracking for approval steps
• 🌐 REST API Ready: Built-in REST API endpoints using Django REST Framework
• 🛠️ Django Admin Integration: Full admin interface for managing workflows
• 🎨 Extensible Handlers: Custom hook system for workflow events with settings-based configuration
• 📝 Form Integration: Optional dynamic form support for approval steps
• ✅ Comprehensive Testing: Full test suite with pytest (77+ tests passing)
• 🔄 Backward Compatibility: Maintains compatibility with existing implementations

🚀 Quick Start

Installation

pip install django-approval-workflow

Django Settings

Add approval_workflow to your INSTALLED_APPS:

INSTALLED_APPS = [
    # ... your apps
    'approval_workflow',
    'mptt',  # Required for hierarchical roles
    'rest_framework',  # Optional, for API endpoints
]

# Optional: Configure handlers like Django MIDDLEWARE
APPROVAL_HANDLERS = [
    'myapp.handlers.DocumentApprovalHandler',
    'myapp.handlers.TicketApprovalHandler',
    'myapp.custom.StageApprovalHandler',
]

# Other optional settings
APPROVAL_ROLE_MODEL = "myapp.Role"  # Default: None
APPROVAL_ROLE_FIELD = "role"  # Default: "role"
APPROVAL_DYNAMIC_FORM_MODEL = "myapp.DynamicForm"  # Default: None
APPROVAL_FORM_SCHEMA_FIELD = "form_info"  # Default: "schema"
APPROVAL_HEAD_MANAGER_FIELD = "head_manager"  # Default: None

Run Migrations

python manage.py migrate approval_workflow

📖 New Simplified Usage

✨ Enhanced advance_flow Interface

The new interface eliminates the need to manually find approval instances:

from approval_workflow.services import start_flow, advance_flow
from django.contrib.auth import get_user_model

User = get_user_model()

# Create users
manager = User.objects.get(username='manager')
employee = User.objects.get(username='employee')

# Your model instance
document = MyDocument.objects.create(title="Important Document")

# Start an approval workflow
flow = start_flow(
    obj=document,
    steps=[
        {"step": 1, "assigned_to": employee},
        {"step": 2, "assigned_to": manager},
    ]
)

# ✨ NEW: Simple interface - just pass the object and user
result = advance_flow(document, 'approved', employee, comment="Looks good!")

# ✨ NEW: Automatic permission checking and error handling
try:
    advance_flow(document, 'approved', unauthorized_user)
except PermissionError as e:
    print(f"Access denied: {e}")
except ValueError as e:
    print(f"No current approval found: {e}")

🔄 All Workflow Actions

# Approve a document
advance_flow(document, 'approved', current_user, comment="Approved by manager")

# Reject with detailed feedback
advance_flow(ticket, 'rejected', current_user, comment="Missing required documentation")

# Request resubmission with additional review steps
advance_flow(
    document, 
    'resubmission', 
    current_user,
    comment="Need legal review before final approval",
    resubmission_steps=[
        {"step": 5, "assigned_to": legal_reviewer},
        {"step": 6, "assigned_to": director}
    ]
)

# Delegate to another user
advance_flow(
    ticket, 
    'delegated', 
    current_user,
    comment="Delegating while on vacation",
    delegate_to=specialist_user
)

# Escalate to higher authority
advance_flow(
    document, 
    'escalated', 
    current_user,
    comment="Escalating for executive approval"
)

⚙️ MIDDLEWARE-Style Handler Configuration

Configure approval handlers in Django settings just like MIDDLEWARE:

# settings.py
APPROVAL_HANDLERS = [
    'myapp.handlers.DocumentApprovalHandler',
    'myapp.handlers.TicketApprovalHandler',
    'myapp.custom.StageApprovalHandler',
]

Create powerful handlers with before/after hooks:

# myapp/handlers.py
from approval_workflow.handlers import BaseApprovalHandler
from django.core.mail import send_mail

class DocumentApprovalHandler(BaseApprovalHandler):
    def before_approve(self, instance):
        """Called before approval processing starts."""
        document = instance.flow.target
        document.status = 'being_approved'
        document.save()
        
    def on_approve(self, instance):
        """Called during approval processing."""
        print(f"Document {instance.flow.target.id} approved by {instance.action_user}")
        
    def after_approve(self, instance):
        """Called after entire workflow completes successfully."""
        document = instance.flow.target
        document.status = 'published'
        document.published_at = timezone.now()
        document.save()
        
        # Send publication notification
        send_mail(
            subject=f'Document "{document.title}" Published',
            message='Your document has been approved and published.',
            from_email='[e-mail]',
            recipient_list=[document.author.email],
        )
    
    def before_reject(self, instance):
        """Called before rejection processing."""
        # Log rejection attempt
        logger.info(f"Document {instance.flow.target.id} about to be rejected")
        
    def after_reject(self, instance):
        """Called after workflow is rejected and terminated."""
        document = instance.flow.target
        document.status = 'rejected'
        document.rejection_reason = instance.comment
        document.save()
        
        # Notify author of rejection
        send_mail(
            subject=f'Document "{document.title}" Rejected',
            message=f'Your document was rejected: {instance.comment}',
            from_email='[e-mail]',
            recipient_list=[document.author.email],
        )
    
    def on_resubmission(self, instance):
        """Called when resubmission is requested."""
        document = instance.flow.target
        document.status = 'needs_revision'
        document.revision_requested_at = timezone.now()
        document.save()
        
        # Create revision task
        RevisionTask.objects.create(
            document=document,
            requested_by=instance.action_user,
            reason=instance.comment,
            due_date=timezone.now() + timedelta(days=7)
        )

🎯 Complete Hook System

Available Hook Methods:

• before_approve(instance) - Called before approval starts
• on_approve(instance) - Called during approval processing
• after_approve(instance) - Called after workflow completes successfully
• before_reject(instance) - Called before rejection starts
• on_reject(instance) - Called during rejection processing
• after_reject(instance) - Called after workflow is rejected and terminated
• before_resubmission(instance) - Called before resubmission starts
• on_resubmission(instance) - Called during resubmission processing
• after_resubmission(instance) - Called after resubmission workflow completes
• before_delegate(instance) - Called before delegation starts
• on_delegate(instance) - Called during delegation processing
• after_delegate(instance) - Called after delegated workflow completes
• before_escalate(instance) - Called before escalation starts
• on_escalate(instance) - Called during escalation processing
• after_escalate(instance) - Called after escalated workflow completes
• on_final_approve(instance) - Called when final step is approved

🎭 Role-Based Workflows

Create sophisticated role-based approval workflows:

from approval_workflow.services import start_flow
from approval_workflow.choices import RoleSelectionStrategy

# Get role instances
manager_role = Role.objects.get(name="Manager")
director_role = Role.objects.get(name="Director")

# Create role-based workflow with different strategies
flow = start_flow(
    obj=document,
    steps=[
        {
            "step": 1,
            "assigned_role": manager_role,
            "role_selection_strategy": RoleSelectionStrategy.ANYONE,
            # Any manager can approve this step
        },
        {
            "step": 2,
            "assigned_role": director_role,
            "role_selection_strategy": RoleSelectionStrategy.CONSENSUS,
            # All directors must approve this step
        }
    ]
)

# Mixed role-based and user-based workflow
mixed_flow = start_flow(
    obj=document,
    steps=[
        {"step": 1, "assigned_to": specific_user},  # User-based step
        {
            "step": 2,
            "assigned_role": manager_role,
            "role_selection_strategy": RoleSelectionStrategy.ROUND_ROBIN,
            # Automatically assigns to manager with least workload
        }
    ]
)

# The new advance_flow automatically handles role-based permissions
advance_flow(document, 'approved', manager_with_role)  # ✅ Works if user has the role
advance_flow(document, 'approved', user_without_role)  # ❌ Raises PermissionError

Role Selection Strategies:

• ANYONE: Any user with the role can approve (first approval completes the step)
• CONSENSUS: All users with the role must approve before advancing
• ROUND_ROBIN: Automatically assigns to the user with the least current assignments

🏗️ Advanced Features

📝 Dynamic Form Integration

# Create form with validation schema
expense_form = DynamicForm.objects.create(
    name="Expense Approval Form",
    schema={
        "type": "object",
        "properties": {
            "amount": {"type": "number", "minimum": 0},
            "category": {"type": "string", "enum": ["travel", "equipment"]},
            "description": {"type": "string", "minLength": 10}
        },
        "required": ["amount", "category", "description"]
    }
)

# Use in workflow with automatic validation
flow = start_flow(
    obj=expense_request,
    steps=[
        {"step": 1, "assigned_to": manager, "form": expense_form}
    ]
)

# Form data is validated automatically
advance_flow(
    expense_request,
    'approved',
    manager,
    form_data={
        "amount": 750.00,
        "category": "travel", 
        "description": "Conference attendance in NYC"
    }
)

🧩 Custom Fields Support

# Add custom metadata to approval steps
flow = start_flow(
    obj=document,
    steps=[
        {
            "step": 1,
            "assigned_to": manager,
            "extra_fields": {
                "priority": "high",
                "department": "IT",
                "requires_signature": True,
                "custom_deadline": "2024-12-31",
                "tags": ["urgent", "compliance"]
            }
        }
    ]
)

# Access in handlers
class CustomApprovalHandler(BaseApprovalHandler):
    def on_approve(self, instance):
        priority = instance.extra_fields.get("priority", "normal")
        if priority == "high":
            send_urgent_notification(instance.assigned_to)

⚡ High-Performance Repository Pattern

from approval_workflow.utils import get_approval_repository, get_approval_summary

# Single optimized query for all operations
repo = get_approval_repository(document)
current = repo.get_current_approval()        # O(1) lookup
next_step = repo.get_next_approval()         # No additional database hit
progress = repo.get_workflow_progress()      # Efficient progress calculation

# Or get comprehensive summary
summary = get_approval_summary(document)
print(f"Progress: {summary['progress_percentage']}%")
print(f"Current step: {summary['current_step'].step_number}")

🔄 Dynamic Workflow Extension

# Extend existing workflows dynamically
new_instances = extend_flow(
    flow=flow,
    steps=[
        {"step": 3, "assigned_to": legal_reviewer},
        {"step": 4, "assigned_role": director_role, "role_selection_strategy": RoleSelectionStrategy.CONSENSUS}
    ]
)

🔧 Migration from Old Interface

The package maintains full backward compatibility:

# OLD interface (still works)
current_step = get_current_approval(document)
advance_flow(instance=current_step, action='approved', user=user)

# NEW interface (recommended)
advance_flow(document, 'approved', user)

🧪 Testing

Run the comprehensive test suite:

# Install development dependencies
pip install -r requirements-dev.txt

# Run all tests (77 tests)
pytest

# Run with coverage
pytest --cov=approval_workflow

🔧 Configuration Reference

Required Settings

INSTALLED_APPS = [
    'approval_workflow',
    'mptt',  # For hierarchical roles
]

Optional Settings

# Handler configuration (MIDDLEWARE style)
APPROVAL_HANDLERS = [
    'myapp.handlers.DocumentApprovalHandler',
    'myapp.handlers.TicketApprovalHandler',
]

# Role model configuration
APPROVAL_ROLE_MODEL = "myapp.Role"  # Must inherit from MPTTModel
APPROVAL_ROLE_FIELD = "role"        # Field linking User to Role

# Form integration
APPROVAL_DYNAMIC_FORM_MODEL = "myapp.DynamicForm"
APPROVAL_FORM_SCHEMA_FIELD = "schema"  # Field containing JSON schema

# Escalation configuration
APPROVAL_HEAD_MANAGER_FIELD = "head_manager"  # Direct manager field

📊 Performance Features

• O(1) Current Step Lookup: Uses denormalized CURRENT status for instant access
• Single Query Strategy: Repository pattern loads all data with one optimized query
• Multi-Level Caching: LRU cache, Django cache, and instance caching
• Strategic Indexing: Only 3 optimized database indexes for maximum performance
• Minimal Database Hits: Designed for high-volume production environments

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

👨‍💻 Author

Mohamed Salah
Email: [e-mail]
GitHub: Codxi-Co

---

Key Improvements in Latest Version:

• ✨ Simplified Interface: New advance_flow(object, action, user) API
• ⚙️ MIDDLEWARE-Style Configuration: Configure handlers in Django settings
• 🎯 Complete Hook System: Before/after hooks for full lifecycle control
• 🔐 Automatic Permission Validation: Built-in user authorization
• 🔄 Full Backward Compatibility: Existing code continues to work
• ✅ Comprehensive Testing: 77 tests ensuring reliability

For detailed examples and advanced usage, see the documentation and test files.