Question

So, I don’t know if the question is explicit enough, but here’s my problem:

I am writing a small application in VB.Net, that retrieves information from a website and present it to the user. Basically, I have written a class, which has a Get(URL) method which retrieves the webpage, reads it and populates the various Properties (Read-only) of the object.
This class works OK.

Now, I would like to store that information in a Database (I’m using Access for now), so that I can read the data from the DB, if the class gets called for a known URL. As I’m fairly new to OOP and completely new to DB usage in desktop applications (no problems in designing the DB though), I am not sure on how to proceed:

• Should I put the database code in my existing class?
• Should I create an extended class based on the existing one, adding the DB code?
• Should I create a completely different class for the DB data and put the switch logic (read from DB or from web) in my application?
• …

I realize that my question may sound silly to the most experienced of you, but I’m new to this and I would really like to learn how to do things the right way the first time!!!

Thanks!

Answer 1

This is what I would do:

• Create a new class for the database code, and create an
  interface for it that it implements.
• Then create another class that has the code to fetch the web data. Make it implement the same interface.

Now you can subsitute either class to do your data access from your controller class.

Also, I usually put database and data access in separate projects from my service and ui classes, which are in their own classes, but that might be overkill for your situation.

If you’d like to read more on the subject, look up n-tier application design. The tier you’re talking about here is data access.

http://en.wikipedia.org/wiki/Data_access_layer