Update of the problem:
After inspecting some more the internal variables of the mysqlpp::sql_blob
and adding some debug code, I found the following:
A) assigning value from within the C++ program:
* The buffer_.counted_.type_.num_ is set to 25, which corresponds to
"VARCHAR NOT NULL".
* If escape_q is called, it returns TRUE.
* Everything works as expected.
B) reading data from database:
* num_ is set to 51, which corresponds to "VARCHAR NULL". Indeed, I
mistakenly forgot to add the "NOT NULL" when creating the table.
* If escape_q is called, it returns FALSE.
* Value doesn't get escaped when adding it to a query (with q <<
mysqlpp::quote << value).
I corrected the table definition and now I get the same type 25 in both
cases.
Question remains if there is a bug in escape_q (returning false for all
"nullable" types), or that this is caused because of a mismatch between
database definition (allowing NULL) and SSQLS definition (not allowing
NULL).
