Add the mapping example

It shows how to map between C++ value types and SQL types

1 files changed, 87 insertions, 0 deletions

diff --git a/mapping/traits.hxx b/mapping/traits.hxx
new file mode 100644
index 0000000..0533360
--- /dev/null
+++ b/mapping/traits.hxx
@@ -0,0 +1,87 @@
+// file      : mapping/traits.hxx
+// author    : Boris Kolpackov <boris@codesynthesis.com>
+// copyright : not copyrighted - public domain
+
+#ifndef TRAITS_HXX
+#define TRAITS_HXX
+
+#include <cstring>
+
+#include "person.hxx"  // date
+
+// MySQL implementation.
+//
+#if defined(DATABASE_MYSQL)
+
+#include <odb/mysql/traits.hxx>
+
+namespace odb
+{
+  namespace mysql
+  {
+    template <>
+    class value_traits<bool, details::buffer, id_string>
+    {
+    public:
+      typedef bool value_type;
+      typedef bool query_type;
+      typedef details::buffer image_type;
+
+      static void
+      set_value (bool& v,
+                 const details::buffer& b,
+                 std::size_t n,
+                 bool is_null)
+      {
+        v = (!is_null && n == 4 && std::strncmp ("true", b.data (), n) == 0);
+      }
+
+      static void
+      set_image (details::buffer& b,
+                 std::size_t& n,
+                 bool& is_null,
+                 bool v)
+      {
+        is_null = false;
+        n = v ? 4 : 5;
+
+        if (n > b.capacity ())
+          b.capacity (n);
+
+        std::memcpy (b.data (), (v ? "true" : "false"), n);
+      }
+    };
+
+    template <>
+    class value_traits<date, MYSQL_TIME, id_date>
+    {
+    public:
+      typedef date value_type;
+      typedef date query_type;
+      typedef MYSQL_TIME image_type;
+
+      static void
+      set_value (date& v, const MYSQL_TIME& i, bool is_null)
+      {
+        if (!is_null)
+          v = date (i.year, i.month, i.day);
+        else
+          v = date (0, 0, 0);
+      }
+
+      static void
+      set_image (MYSQL_TIME& i, bool& is_null, const date& v)
+      {
+        is_null = false;
+        i.neg = false;
+        i.year = v.year ();
+        i.month = v.month ();
+        i.day = v.day ();
+      }
+    };
+  }
+}
+
+#endif // DATABASE_MYSQL
+
+#endif // TRAITS_HXX