Error while posting relational data with Tastypie

Question

I have these two models:

class Order(models.Model):
    shop = ForeignKey(Shop)
    date_modified = DateTimeField(auto_now=True)

    class Meta:
        db_table = 't_order'

class Transaction(models.Model):
    order = ForeignKey('Order')
    quantity = IntegerField()
    item = ForeignKey(Item)
    date_modified = DateTimeField(auto_now=True)

    class Meta:
        db_table = 't_transaction'

and two resources:

class OrderResource(ModelResource):
    shop = fields.ToOneField(ShopResource, 'shop')
    transactions = fields.ToManyField('TransactionResource','transaction_set', full=True)

    class Meta:
        queryset = Order.objects.all()
        resource_name = 'order'
        authentication = Authentication()
        authorization = Authorization()
        allowed_methods = ['post', 'get']
class TransactionResource(ModelResource):
        order = fields.ToOneField('OrderResource', 'order')
        item = fields.ToOneField('ItemResource', 'item')
    class Meta:
        queryset = Transaction.objects.all()
        resource_name = 'transaction'
        authentication = Authentication()
        authorization = Authorization()
        allowed_methods = ['post', 'get']

I am posting this data to

http://127.0.0.1:5000/api/order/

:

{
 "shop": "/api/shop/1/",
 "transactions": [
        {
                "item": "/api/item/6/",
                "quantity" : 2
        }
    ]
}

I am getting following error:

"error_message": "Transaction has no order.",

if I remove

order = fields.ToOneField('OrderResource', 'order')

line from TransactionResource I am getting:

"error_message": "(1048, "Column 'order_id' cannot be null")",

Where am I wrong?

Answer 1

You are missing the related_name attribute in the transactions ToManyField definition. instead of:

transactions = fields.ToManyField('ttests.api.TransactionResource','transaction_set', full=True)

you should use:

transactions = fields.ToManyField('ttests.api.TransactionResource','transaction_set', full=True, related_name='order')

Then tastypie will not expect that you provide the order inside the transaction when you're posting a transaction.