Wt

I have that postgres database structure:

|--------------|             |--------------------------------|
| table_a      |             | table_b                        |
|--------------|             |--------------------------------|
| id bigint PK |-------------| id_a bigint PK FF table_a(id)  |
| field1 text  |             | field3 text                    |
| field2 text  |             | field4 text                    |
|--------------|             | idta bigint FK table_a(id)     |
                             |--------------------------------|

As you can see, table_ba has a field that is PK and FK.

I tryed :
table_b.h

namespace Wt {
  namespace Dbo {

    template<>
    struct dbo_traits<TableB> : dbo_default_traits
    {
       static const char *surrogateIdField() { return nullptr; }
    };
  }
}
class TableB 
{
public:
    TableB();
    template <class Action>
    void persist(Action &a)
    {
        Wt::Dbo::id(a,tableAPTR,">id_a",Wt::Dbo::NotNull);
        Wt::Dbo::field(a,field3,"field3");
        Wt::Dbo::field(a,field4,"field4");    
    }

private:
    Wt::Dbo::ptr<TableA> tableAPTR;
    Wt::WString field3;
    Wt::WString field4;

};

table_a.h

class TableA 
{
public:
    TableA();
    template <class Action>
    void persist(Action &a)
    {
        Wt::Dbo::hasOne(a,tableBPTR,">id_a",Wt::Dbo::NotNull);
        Wt::Dbo::field(a,field1,"field1");
        Wt::Dbo::field(a,field2,"field2");    
    }

private:
    Wt::Dbo::weak_ptr<TableB> tableBPTR;
    Wt::WString field1;
    Wt::WString field2;

};

But it gives me those errors:

cannot convert 'Wt::Dbo::ptr<TableA>' to 'cons IdType&' {aka 'const long long int&'}