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diff --git a/doc/manual.xhtml b/doc/manual.xhtml index 690c17f..d262319 100644 --- a/doc/manual.xhtml +++ b/doc/manual.xhtml @@ -3837,6 +3837,9 @@ namespace odb void load (T& x); + + typename object_traits<T>::id_type + id (); }; } </pre> @@ -3905,6 +3908,25 @@ namespace odb } </pre> + <p>The <code>id()</code> function return the object id of the current + object. While we can achieve the same by loading the object and getting + its id, this function is more efficient since it doesn't actually + create the object. This can be useful when all we need is the object's + identifier. For example:</p> + + <pre class="c++"> + std::set<unsigned long> set = ...; // Persons of interest. + + result r (db.query<person> (query::first == "John")); + + for (result::iterator i (r.begin ()); i != r.end (); ++i) + { + if (set.find (i.id ()) != set.end ()) // No object loaded. + { + cout << i->first () << endl; // Object loaded. + } + } + </pre> <!-- CHAPTER --> |