cryptoassets.django 0.1

Cryptoassets library integration for Django

This package provides integration of cryptoassets.core Bitcoin and cryptoasset framework for Django web framework.

Features

• Use Django settings.py configure mechanism to set up cryptoassets.core
• Django management command mappings for cryptoassets helper service
• Django native logging
• Django event dispatch integration
• Setting up SQLAlchemy sessions and database conflict resolution inside Django

Usage

Add cryptoassets.django to your Django application list in settings.py:

INSTALLED_APPS = (
    'cryptoassets.django',
)

Add cryptoassets.core configuration as Python dictionary to your Django settings.py module under CRYPTOASSETS variable.

Example for settings.py:

# TESTNET settings
CRYPTOASSETS = {

    # It is recommended to use separate database for cryptoassets,
    # but you can share the database with Django as well.
    # In any case, cryptoassets
    # will use a separate db connection.
    # cryptoassets.django does not read the existing DATABASES setting.
    # Configure the connection using SQLAlchemy syntax:
    # http://cryptoassetscore.readthedocs.org/en/latest/config.html#database
    "database": {
        "url": "postgresql://localhost/cryptoassets",
        "echo": False,
    },

    # Configure block.io API service with Bitcoin testnet
    # (let's not play around with real Bitcoins yet)
    "coins": {
        "btc": {
            "backend": {
                "class": "cryptoassets.core.backend.blockio.BlockIo",
                "api_key": "923f-xxxx-yyyy-zzzz",
                "network": "btctest",
                "pin": "foobar123",
                # Cryptoassets helper process will use this UNIX named pipe to communicate
                # with bitcoind
                "walletnotify": {
                    "class": "cryptoassets.core.backend.sochainwalletnotify.SochainWalletNotifyHandler",
                    "pusher_app_key": "e9f5cc20074501ca7395"
                },
            }
        },
    },

    # Bind cryptoassets.core event handler to Django dispacth wrapper
    "events": {
        "django": {
            "class": "cryptoassets.core.event.python.InProcessEventHandler",
            "callback": "cryptoassets.django.incoming.handle_tx_update"
        }
    },

    # Start simple status at port 9001 for diagnostics
    "status_server": {
        "ip": "127.0.0.1",
        "port": 9001
    }
}

Note

If you copy-paste these settings please sign up at block.io for your own API key.

Initializing database

Run:

python manage.py cryptoassets_initialize_database

This will build database tables for configured cryptocurrencies.

This is Django management command warpper for cryptoassets-initialize-database.

Starting cryptoassets helper service

Start a helper service. This standalone process runs, connects to APIs and networks, listens to incoming transactions, broadcasts outgoing transaction.

Note

Cryptoassets helper service does not run within your web server process. It runs as a standalone process on your server.

Run:

python manage.py cryptoassets_helper_service

For more information see helper service command.

Handling incoming transactions

Make sure walletnotify is configured in CRYPTOASSETS setting as described above. It will translate incoming interprocess communication to Django events.

Grab incoming transactions in your application code in txupdate signal:

from cryptoassets.django.signals import txupdate
from django.dispatch import receiver

@receiver(txupdate)
def txupdate_received(event_name, data, **kwargs):
    """ Received transaction update from cryptoassets.core.

    """

    if data.get("transaction_type") != "deposit":
        # We are only interest updates on incoming transctions
        return

    transaction_hash = data["txid"]
    value = data['amount']
    address = data['address']
    confirmations = int(data.get('confirmations', -1))

    logger.info("Transaction update received: %s BTC:%s address:%s confirmations:%d", transaction_hash, value, address, confirmations)

The handler is executed inside cryptoassets helper service process.

More information about cryptoassets.core events.

Accessing cryptoassets data

Accessing database models

To get access to database models:

from cryptoassets.django.app import get_cryptoassets

cryptoassets = get_cryptoassets()
BitcoinWallet = cryptoassets.coins.get("btc").coin_description.Wallet

Making database queries

All database access goes through a separate SQLAlcemy session which is wrapped with database transaction conflict resolver.

For convenience, cryptoassets.django.assetsdb.managed_transaction() decorator is provided:

Example code:

from cryptoassets.django.app import get_cryptoassets
from cryptoassets.django import assetdb

def get_wallet(session):
    """Return the master shared wallet used to receive payments. """
    cryptoassets = get_cryptoassets()
    BitcoinWallet = cryptoassets.coins.get("btc").coin_description.Wallet
    wallet = BitcoinWallet.get_or_create_by_name("default", session)
    return wallet

def create_new_receiving_address(label):

    @assetdb.managed_transaction
    def tx(session):

        wallet = get_wallet(session=session)

        account = wallet.get_or_create_account_by_name("my account")
        session.flush()  # account id gets written inside commit
        addr = wallet.create_receiving_address(account, label)
        logging.info("Created receiving address %s", addr.address)
        address = addr.address
        return address

    return tx()

The rest is by model API and SQLAlchemy.

Other

Example Django application

See Liberty Music Store (source code).

cryptoassets.core tutorial

See getting started.

Running helper service as system service

To have automatic start/stop and other functionality for cryptoassets helper service, use something akin systemd or supervisord to manage python manage.py cryptoassets_helper_service.

Author

Mikko Ohtamaa (blog, Facebook, Twitter, Google+)