Convert C++/CLI User Defined Object (%) to Native C++ object (&)

Question

How can I convert a user defined object passed by (%) to a native object (&). For example

void managed_func(user_defined_managed_obj% m_obj_)
{
    // i need this
    obj_ptr->unmanaged_func(&m_obj_);
}

Thus, in the above example I would like to pass the managed object %m_obj_ to the argument of the unmanaged_func. Here user_defined_managed_obj is a .net wrapper in C++/CLI that is a bridge for a native C++.

I've tried the following:

pin_ptr<user_defined_unmanaged_obj> tmp_ptr = &m_obj_;
obj_ptr->unmanaged_func(*tmp_ptr);

Will someone point me into the right direction or let me know what I can do to remedy this problem. Thank you.

Edit: The user_defined_unmanaged_obj is a native C++ object and the user_defined_managed_obj is the wrapper C++/CLI class for it.

Edit: The following are the code In native C++, native_sql.h

#include <string>
class native_sql
{
public:
    native_sql(string arguments)
    {...some codes}
    ~native_sql(void) = default;
    void connect(void) {...some codes}
    void clean(void)   {...some codes}
}

In native C++, native_upload_specific_data.h

#include "native_sql.h"
#include <string>
class native_upload_specific_data
{
public:
    native_upload_specific_data(string arugments) {...some codes}
    ~native_upload_specific_data(void)
    void upload(native_sql& sql_obj_) {...some codes}
}

In C++/CLI, sql_wrapper.h

#include <msclr\marshal_cppstd.h>
#include "../native_sql.h"
#include "../native_sql.cpp"
using namespace System;
public ref class sql_wrapper
{
public:
    sql_wrapper(String^ arguments) 
    {...codes to convert String^ to std::string and pass args to
    new native_sql}
    ~sql_wrapper(void) { delete sql_ptr; }
    void connect_wrapper(void) { sql_ptr->connect(); }
    void clean_wrapper(void) { sql_ptr->clean(); }

    native_sql* sql_ptr;
}

In C++/CLI wrapper, upload_specific_data_wrapper.h

#include "../native_upload_specific_data.h"
#include "../native_upload_specific_data.cpp"
using namespace System;
public ref class upload_specific_data_wrapper
{
public:
    upload_specific_data_wrapper(String^ arguments)
    {...convert String^ args into std::strings and pass to 
    native_upload_specific_data ctor}
    ~upload_specific_data_wrapper(void) { delete data_ptr; }
    void upload(sql_wrapper% sql_obj_)
    {
        // here is where I have the problem
        pin_ptr<native_sql*> ptr = &(sql_obj_.sql_ptr);
        data_ptr->upload(ptr);
    }
    native_upload_specific_data* data_ptr;
}

The error I receive is

C2664: 'void native_upload_specific_data(native_sql&)': cannot convert arugment 1 from cli::pin_ptr<native_sql*> to native_sql&

....Thank you.