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User Domain Example

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This example demonstrates a complete user management domain with create, update, and deactivate operations.

Overview​

This example shows how to build a user management domain using Fluvius Framework. It includes:

  • User aggregate with business logic
  • Commands for user operations
  • Events for state changes
  • State management

Complete Example​

Aggregate Definition​

from fluvius.domain import Aggregate, action
from fluvius.data import DataModel, field, UUID_TYPE

class UserState(DataModel):
    name: str = field()
    email: str = field()
    active: bool = field(initial=True)
    created_at: datetime = field(factory=timestamp)

class UserAggregate(Aggregate):
    def __init__(self, domain):
        super().__init__(domain)
        self._state = None
    
    @action(evt_key='user-created', resources=['user'])
    async def create_user(self, name: str, email: str):
        """Create a new user"""
        if self._state is not None:
            raise ValueError("User already exists")
        
        self._state = UserState(
            name=name,
            email=email,
            active=True
        )
        return self._state
    
    @action(evt_key='user-updated', resources=['user'])
    async def update_user(self, name: str = None, email: str = None):
        """Update user information"""
        if self._state is None:
            raise ValueError("User does not exist")
        
        updates = {}
        if name is not None:
            updates['name'] = name
        if email is not None:
            updates['email'] = email
        
        self._state = self._state.update(**updates)
        return self._state
    
    @action(evt_key='user-deactivated', resources=['user'])
    async def deactivate_user(self):
        """Deactivate a user"""
        if self._state is None:
            raise ValueError("User does not exist")
        
        self._state = self._state.update(active=False)
        return self._state

Domain Definition​

from fluvius.domain import Domain
from .aggregate import UserAggregate

class UserDomain(Domain):
    __aggregate__ = UserAggregate
    
    class Meta:
        revision = 1
        tags = ["user", "identity"]
        title = "User Management Domain"
        description = "Domain for managing user accounts"

Usage​

import asyncio
from fluvius.domain.context import SanicContext
from fluvius.data import UUID_GENR
from user_domain import UserDomain

async def main():
    # Create context
    ctx = SanicContext.create(namespace='app-user')
    
    # Create domain
    domain = UserDomain(ctx)
    
    # Set aggregate root
    user_id = UUID_GENR()
    domain.set_aggroot('user', user_id)
    
    # Create and process commands
    commands = [
        domain.create_command('create-user', {
            'name': 'John Doe',
            'email': '[email protected]'
        }),
        domain.create_command('update-user', {
            'name': 'Jane Doe'
        }),
        domain.create_command('deactivate-user')
    ]
    
    # Process commands
    async for response in domain.command_processor.process(*commands):
        print(f'Response: {response}')
    
    # Query state
    user = await domain.statemgr.fetch('user', user_id)
    print(f'Final state: {user}')

if __name__ == '__main__':
    asyncio.run(main())

Key Concepts​

  1. Aggregate: Contains business logic and manages state
  2. Actions: Methods decorated with @action that generate events
  3. Commands: Created using domain.create_command()
  4. State: Managed through the aggregate and accessible via statemgr
  5. Events: Automatically generated from actions

Next Steps​