Re: [Cppcms-users] How to catch CPPDB errors

[Marcel H. <ke...@co...>]

Am 23.01.2013 14:50, schrieb Artyom Beilis:
> I would suggest in general...
> 
> Not get into situations where you can get a error, or at least if you
> expect a error catch it.
Think of registration. A Username should be unique and a email adrress
should be unique too. I will not check this, because IMO this is a task
for the database.
> 
> What kind of errors can happen:
> 
>  1. Constrain violation:
>       * Check it before from a transaction assuming isolation
>       * Catch at specific point - assume that the error is constraint
>         violation.
>  2. Deadlock - due to colliding statements - not much to do. Or let 500
>     response to happen or catch a cppdb error at the root of you
>     app hierarchy main and say (oops)
>  3. Connection errors or other stuff - 500 is more than reasonable - or
>     do it what you did in 2
> 
> Now about specific errors.
> 
> Probably it would be good idea to derive several sub exceptions like:
> 
> cppdb::constraint_error
> cppdb::deadlock_error  
> cppdb::connection_error
Could be good, but there are over 100 errors that can happen while you
execute a statement. But i will have a look and see what i can do.
> 
> Similarly to the current
> set: http://cppcms.com/sql/cppdb/classcppdb_1_1cppdb__error.html
> 
> Maybe some more I can't think about them right now.
> 
> But this requires some code writing and what is even more important -
> updating each backend and probably
> the most hard would be ODBC.
> 
> Any volunteers?
> 
>  
> Artyom Beilis

Marcel