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+// file : inverse/driver.cxx
+// copyright : not copyrighted - public domain
+
+#include <memory> // std::unique_ptr
+#include <iostream>
+
+#include <odb/database.hxx>
+#include <odb/session.hxx>
+#include <odb/transaction.hxx>
+
+#include "database.hxx" // create_database
+
+#include "employee.hxx"
+#include "employee-odb.hxx"
+
+using namespace std;
+using namespace odb::core;
+
+void
+print (const employee& e)
+{
+ cout << e.first () << " " << e.last () << endl
+ << " employer: " << e.employer ().load ()->name () << endl
+ << " position: " << e.position ().load ()->title () << endl;
+
+ const projects& ps (e.projects ());
+
+ for (projects::const_iterator i (ps.begin ()); i != ps.end (); ++i)
+ {
+ const lazy_shared_ptr<project>& p (*i);
+ p.load ();
+
+ cout << " project: " << p->name () << endl;
+ }
+
+ cout << endl;
+}
+
+int
+main (int argc, char* argv[])
+{
+ try
+ {
+ unique_ptr<database> db (create_database (argc, argv));
+
+ // Create a few persistent objects.
+ //
+ {
+ // Simple Tech Ltd.
+ //
+ {
+ shared_ptr<employer> er (new employer ("Simple Tech Ltd"));
+
+ shared_ptr<position> he (new position ("Hardware Engineer"));
+ shared_ptr<position> se (new position ("Software Engineer"));
+
+ shared_ptr<project> sh (new project ("Simple Hardware"));
+ shared_ptr<project> ss (new project ("Simple Software"));
+
+ shared_ptr<employee> john (new employee ("John", "Doe", er, he));
+ shared_ptr<employee> jane (new employee ("Jane", "Doe", er, se));
+
+ // Set the inverse side of the employee-employer relationship.
+ //
+ er->employees ().push_back (john);
+ er->employees ().push_back (jane);
+
+ // Set the inverse side of the employee-position relationship.
+ //
+ he->employee (john);
+ se->employee (jane);
+
+ // Set the employee-project relationship (both directions).
+ //
+ john->projects ().push_back (sh);
+ john->projects ().push_back (ss);
+ jane->projects ().push_back (ss);
+
+ sh->employees ().push_back (john);
+ ss->employees ().push_back (john);
+ ss->employees ().push_back (jane);
+
+ transaction t (db->begin ());
+
+ db->persist (er);
+
+ db->persist (he);
+ db->persist (se);
+
+ db->persist (sh);
+ db->persist (ss);
+
+ db->persist (john);
+ db->persist (jane);
+
+ t.commit ();
+ }
+
+ // Complex Systems Inc.
+ //
+ {
+ shared_ptr<employer> er (new employer ("Complex Systems Inc"));
+
+ shared_ptr<position> he (new position ("Hardware Engineer"));
+ shared_ptr<position> se (new position ("Software Engineer"));
+
+ shared_ptr<project> ch (new project ("Complex Hardware"));
+ shared_ptr<project> cs (new project ("Complex Software"));
+
+ shared_ptr<employee> john (new employee ("John", "Smith", er, se));
+ shared_ptr<employee> jane (new employee ("Jane", "Smith", er, he));
+
+ // Set the inverse side of the employee-employer relationship.
+ //
+ er->employees ().push_back (john);
+ er->employees ().push_back (jane);
+
+ // Set the inverse side of the employee-position relationship.
+ //
+ he->employee (john);
+ se->employee (jane);
+
+ // Set the employee-project relationship (both directions).
+ //
+ john->projects ().push_back (cs);
+ jane->projects ().push_back (ch);
+ jane->projects ().push_back (cs);
+
+ ch->employees ().push_back (jane);
+ cs->employees ().push_back (john);
+ cs->employees ().push_back (jane);
+
+ transaction t (db->begin ());
+
+ db->persist (er);
+
+ db->persist (he);
+ db->persist (se);
+
+ db->persist (ch);
+ db->persist (cs);
+
+ db->persist (john);
+ db->persist (jane);
+
+ t.commit ();
+ }
+ }
+
+ // Load Simple Tech Ltd and print its employees. We use a session in this
+ // and subsequent transactions to make sure that a single instance of any
+ // particular object (e.g., employer) is shared among all objects (e.g.,
+ // employee) that relate to it.
+ //
+ {
+ session s;
+ transaction t (db->begin ());
+
+ shared_ptr<employer> stl (db->load<employer> ("Simple Tech Ltd"));
+
+ employees& es (stl->employees ());
+
+ for (employees::iterator i (es.begin ()); i != es.end (); ++i)
+ {
+ lazy_weak_ptr<employee>& lwp (*i);
+ shared_ptr<employee> p (lwp.load ()); // Load and lock.
+ print (*p);
+ }
+
+ t.commit ();
+ }
+
+ // Find all Software Engineers.
+ //
+ {
+ typedef odb::query<position> query;
+ typedef odb::result<position> result;
+
+ session s;
+ transaction t (db->begin ());
+
+ result r (db->query<position> (query::title == "Software Engineer"));
+
+ for (result::iterator i (r.begin ()); i != r.end (); ++i)
+ {
+ const lazy_weak_ptr<employee>& lwp (i->employee ());
+ shared_ptr<employee> p (lwp.load ()); // Load and lock.
+
+ // Employee can be NULL if the position is vacant.
+ //
+ if (p)
+ print (*p);
+ }
+
+ t.commit ();
+ }
+
+ // John Doe has moved to Complex Systems Inc and is now working as
+ // a Software Engineer on Complex Software.
+ //
+ {
+ typedef odb::query<employee> query;
+
+ session s;
+ transaction t (db->begin ());
+
+ // Create "unloaded" pointers to the employer and project objects.
+ //
+ lazy_shared_ptr<employer> csi (*db, std::string ("Complex Systems Inc"));
+ lazy_shared_ptr<project> cs (*db, std::string ("Complex Software"));
+
+ // Create a new Software Engineer position.
+ //
+ shared_ptr<position> se (new position ("Software Engineer"));
+
+ shared_ptr<employee> john (
+ db->query_one<employee> (query::first == "John" &&
+ query::last == "Doe"));
+
+ john->employer (csi);
+ john->position (se);
+ john->projects ().clear ();
+ john->projects ().push_back (cs);
+
+ db->persist (se);
+ db->update (john);
+
+ t.commit ();
+ }
+
+ // Print Complex Systems Inc's employees. This time, instead of loading
+ // the employer object, we use a query which shows how we can use members
+ // of the pointed-to objects in the queries.
+ //
+ {
+ typedef odb::query<employee> query;
+ typedef odb::result<employee> result;
+
+ session s;
+ transaction t (db->begin ());
+
+ result r (db->query<employee> (
+ query::employer->name == "Complex Systems Inc"));
+
+ for (result::iterator i (r.begin ()); i != r.end (); ++i)
+ print (*i);
+
+ t.commit ();
+ }
+ }
+ catch (const odb::exception& e)
+ {
+ cerr << e.what () << endl;
+ return 1;
+ }
+}