[odb-users] SQLite and std::wstring

Boris Kolpackov boris at codesynthesis.com
Thu Jun 7 08:46:40 EDT 2012

Hi Philippe,

Philippe Cadieux-Pelletier <philly.dilly at gmail.com> writes:

> It seems like a pretty severe shortcoming of the SQLite database binding
> not to support std::wstring.

I wouldn't call it "severe" since you can easily add a custom mapping
for the std::wstring type (see the 'mapping' example).

> Are there any plans to add support?

Yes, we can implement built-in support if you need it. 

> I can think of two ways to add support off the top of my head:
>    1. Have some kind of setting, either at compile time or runtime, that
>    will bind SQLite's TEXT type to std::wstring and configure the SQLite
>    database to use utf16 for TEXT. This would mean that you would have to pick
>    either utf8 or utf16, but at least you'd have the option of supporting
>    std::wstring.
>    2. C++ 11 adds std::codecvt_utf8_utf16 to convert between utf8 and
>    utf16. It would then be possible to convert at runtime therefore being able
>    to support both std::string and std::wstring

In SQLite the database encoding (specified with 'PRAGMA encoding') and
the encoding used in the application to bind parameters/results are
somewhat independent. That is, if the database is UTF-8 and we pass
UTF-16 text or if the database is UTF-16 and we pass UTF-8, then
SQLite performs automatic conversions as required. So, in this light,
it would be best to pass std::wstring as UTF-16 and let SQLite
determine what to do. This will also give the user the flexibility
to make the database either UTF-8 or UTF-16 without any changes to
ODB or generated code.

BTW, which database encoding are you planning to use in your case? 


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