We have a very big application written in C++ using the MFC framework (millions of code lines). No need to say that it's a legacy system, but it's also heavily maintained and updated. This application lacks a lot of architecture. For example, we have a lot of classes that do queries directly to the database, which creates a lot of difficulty for unit testing.
I have read the book Working Effectively With Legacy Code, and one of the most important things to do first is to create some kind of architecture so we can separate the GUI from the logic and from the database.
My idea to go towards this is to create something like a database facade. There will be 2 goals for this:
- Encapsulate all the calls to the database behind this facade.
- Be able to test the facade in batch to detect errors in the SQL very fast.
The database facade itself will be implementing an IDatabaseXXXX interface so it could be easily mocked in the unit tests. The second goal will be to be able to run all the functions in the facade in batch to test if there are errors in the SQL queries. I don't count them as unit tests and would be running them only once per day.
My main concern about doing this is that I don't know if there is an existing framework or library to take care of this abstraction. As far as I know, there are some on other platforms like .NET, but it seems that for C++ or MFC, there are not a lot of options. Like I said, the application is very big and the change will be done slowly, mostly when new queries are added to the software.
I think it is a good thing to add that we also have a LOT of recordsets (one for almost each object). For the moment, I don't know how to deal with them, so I kept them on the side and decided to deal with the regular SQL queries. But if you have suggestions to deal with recordsets, I will be glad to hear them.
So my main question is: Is this whole idea of database facade worth trying? Is there any library of framework to help me in this adventure? If there are C++/MFC programmers out there, how do you deal with the abstraction of the query to the database?
Thanks!
EDIT
Some people on the chat suggest looking up at repository pattern which I knew from the world of MVC 3. Any suggestion or tutorial about the repository pattern in C++? Most of what I found is in the .NET world.
