Transaction, Merchant and Category object model from my personal finance mini-hackathon http://ollieglass.com/2013/01/30/personal-finance-mini-hackathon

Object model.py

class Category(models.Model):
    name = models.CharField(max_length=255)


class Merchant(models.Model):
    name = models.CharField(max_length=255)
    category = models.ForeignKey(Category, blank=True, null=True, db_index=True)


class Transaction(models.Model):
    transaction_date = models.DateTimeField(db_index=True)
    posting_date = models.DateTimeField(null=True)

    billing_amount = models.FloatField(max_length=255)

    merchant_raw = models.CharField(max_length=255)

    merchant = models.ForeignKey(Merchant, db_index=True)
    merchant_town = models.CharField(max_length=255)
    merchant_county = models.CharField(max_length=255)
    merchant_postcode = models.CharField(max_length=255)

    reference_number = models.CharField(max_length=255)
    debit_credit_flag = models.CharField(max_length=255)
    sicmcc_code = models.CharField(max_length=255)