[odb-users] XML type for a class member using ODB and postgresql

[Boris Kolpackov]

Hi,

Simón Emmanuel Gutiérrez Brida <simon.gutierrez.brida at gmail.com> writes:

> #pragma db type("XML")
> std::string data;
> 
> But when I compile with odb I get
> 
> error: unknown PostgreSQL type 'XML'

In ODB database types like PG XML are called "extended database types"
and are no mapped automatically (there are too many such types and
different applications often require different mappings).

Instead, what ODB does is provide a generic mechanism that allows
you to map any extended database type to any C++ type via one of
the "core database types" that are natively supported by ODB. This
article describes this mechanism in detail:

http://www.codesynthesis.com/~boris/blog/2012/07/18/custom-database-to-cxx-type-mapping-in-odb/

In your case, you can use TEXT as the core type and the mapping
expression could look something like this (based on the PG docs,
I haven't tested it myself):

#pragma db map type("XML")       \
               as("TEXT")        \
               to("XMLPARSE(DOCUMENT (?))") \
               from("XMLSERIALIZE(DOCUMENT (?) AS TEXT)")

Let us know if this works for you.

Boris