Decode the QR billing information in a structured data model

[ChrisBerna]

As promised with this PR the raw text containing the QR billing information is decoded in a structured data model based on the syntax definition of Swico. I added the new property in the Bill class which will be filled only in the Decode method of QRCodeText.

[manuelbl]

Thanks for the PR. I will look into it.

[manuelbl]

I've had a first look at it. It's quite comprehensive and of good quality. There are a few aspect however that probably need to be changed:

• The code implements the SWICO S1 standard. The QR bill standard is designed to support several standards. So I think the classes and properties should be designed and named such that additional bill information standards can be added later.
• Renaming Bill.BillInformation to Bill.BillInformationText makes sense except it breaks backward compatibility. At the moment I'm not willing to do that.
• Dictionary<double, double> (in BillInformation) is not the best choice. I don't think it will ever be access by key. So a list would be a better choice. And decimal should be preferred over double for financial amounts as they can introduce funny effects (such as 2.499999 instead of 2.5).
• The error handling breaks the error handling strategy of QRCodeText.Decode as a different exception is thrown for the bill information field than for all other fields.
• The bill information field is hardly validated. An exception is only thrown if the field doesn't start with //S1/. All other errors are ignored.

Is it ok if I take it over for the next steps?

Is it ok if your code is put under MIT license? I would still like to name you as the author(s). With what name would you like to be mentioned?

[ChrisBerna]

Hello, thanks for your feedback and yes please feel free to improve or change parts of my implementation. The license MIT is perfectly fine and thank you very much for putting me as Author (Christian Bernasconi).

[manuelbl]

I've taken your code and made the modifications to address the above issues:

1. Structured bill information is only decoded on demand in order not to break backward compatibility. The relevant method is Bill.RetrieveSwicoBillInformation.
2. Bill.BillInformation remains a string property. Structured bill information can be set with SetSwicoBillInformation.
3. The structured bill information is checked in detail when it's decoded. If an error is detected, an exception is thrown.
4. VAT details, VAT import taxes and payment conditions are provided as a list of tuples.

Regarding item 3: After having changed your code quite considerably, I'm no longer sure it's a good approach. Depending on the use case, it might be more beneficial to decode as much as possible instead of stopping at the first problem. What do you think?

The code is in a separate branch (and not in your PR): https://github.com/manuelbl/SwissQRBill.NET/tree/swico-bill-info

[ChrisBerna]

I had a quick look at your branch, well done thank you very much! I find a good idea to decode the bill information only on demand and regarding point 3 in my opinion would be better to decode as much as possible instead of throwing an exception.

[manuelbl]

So the decoding approach is different now: no exceptions are thrown at all. Errors are silently ignored.

I'd appreciate it if you could have a look at the API (mainly the new methods in Bill , SwicoBillInformation and the decoding approach) and give me feedback if it's understandable, makes sense and is useful in typical ERP/accounting project and your project (whatever it is).

[ChrisBerna]

Perfect, thank you! I checked the branch and in my opinion the code is very well done, the only little suggestion would be to move the constants like InvoiceNumberTag in a separated class so that they can also be used in the SwicoS1Encoder class.

[manuelbl]

Thanks for your contribution. I've now released it as version 2.3.

This solves issue #8