Re: [Cppcms-users] Cppdb: How to fetch a column of unknown type at compile time?

[Artyom <art...@ya...>]

> 
> How to fetch a column of unknown type at compile time with cppdb?
> 

You can always fetch it as string, any value (with small exception of Binary 
Large OBjects)
is convertible to string and actually under the hood it is almost always string.

Why there is no functionality to get the type of the column?

Because it is not always well defined. With some databases like sqlite3
the data is "typeless" and even sometimes when you fetch a column
it may have some "original" type it does not promises that it
would be actually the type you are trying to use or it may be
even undefined as it is some combined value.

Bottom line:

- CppDB is dynamically typed and try to perform the conversions
  in the best way it can.

- If you need to check whether specific value can be treated as
  for example integer, you can do following:

      try {
        int x = r.get<int>(v);
      }
      catch(cppdb::bad_value_cast const &e) {
        // ok it can't be integer
      }
  
   But of course of the original type is string and it holds the text
   "123" as string, cppdb would happily cast if for you.


Artyom