[odb-users] Persisting empty binary values error. Microsoft SQL Server

[Andrey Paraskevopulo]

I need to store empty binary values in the binary fields.

I’ve try to persist record with empty std::vector<char> (or unsigned char),
but this lead to program termination.

(no matter what was the mapping type – varbinary(max) or image).



After short investigation I think that I’ve found the error.

odb\mssql\traits.cxx

void default_value_traits<std::vector<char>, id_long_binary
>::param_callback(...){

...

*buffer = &v.front ();

Calling std::vector::front function on an empty container causes undefined
behavior.



Possible solution:

replace this string with:

*buffer = v.empty()?nullptr:&v.front ();

(for both char and unsigned char).



I am not sure about side effects, but persisting empty vectors is working.

odb version 2.4.0


Andrey Paraskevopulo