RFE: API to get PayPal payment's transaction fee amount

[radekholy24]

Hello,

we'd like to ask you to provide API to get PayPal payment's transaction fee amount.

IIUIC, the actual amount can vary among different payments based on PayPal's rules. The amount can be obtained e.g. from the responses to Execute approved PayPal payment requests which are being sent by the PaypalProvider.process_data method.

We are willing to make a pull request that implements this but we need to discuss what would be the desired implementation first. Where would you prefer to store the fee amount and what way would you prefer a user to get the information (a field, a property, a method, ...)? Also, how would you prefer the pull request to handle the other payment providers? I am afraid that we miss the necessary knowledge of how to get the fee amount from other payment gateways.

[PetrDlouhy]

Getting transaction fee for payments could be important e.g. for accounting purposes and other.

I think this behavior should be abstracted between providers: There should be common method of getting transaction fee for the (Base)Payment objects.

Various payment providers could have different ways to obtain the fee for payment transaction. Even the logic could differ - e.g. PayPal gives it in response data, PayU doesn't provide such information, but it might be calculated with fixed values (maybe set in payment provider settings).