Implement {query,execute}_{one,value}() shortcut functions

Useful in situations where the query is know to return at most one element
(*_one) or exactly one element (*_value).

2 files changed, 42 insertions, 2 deletions

diff --git a/common/prepared/driver.cxx b/common/prepared/driver.cxx
index dfbdf13..ee690a1 100644
--- a/common/prepared/driver.cxx
+++ b/common/prepared/driver.cxx
@@ -411,6 +411,46 @@ main (int argc, char* argv[])
 
       t.commit ();
     }
+
+    // Test execute_one() and execute_value().
+    //
+    {
+      transaction t (db->begin ());
+
+      person p ("John Doe", 23);
+      db->persist (p);
+
+      prep_query pq1 (
+        db->prepare_query<person> ("query-1", query::id == p.id_));
+      prep_query pq0 (
+        db->prepare_query<person> ("query-0", query::id == p.id_ + 1));
+
+      {
+        auto_ptr<person> p (pq1.execute_one ());
+        assert (p.get () != 0 && p->name_ == "John Doe");
+      }
+
+      {
+        auto_ptr<person> p (pq0.execute_one ());
+        assert (p.get () == 0);
+      }
+
+      {
+        person p;
+        assert (pq1.execute_one (p) && p.name_ == "John Doe");
+      }
+
+      {
+        person p ("", 0);
+        assert (!pq0.execute_one (p) &&
+                p.id_ == 0 && p.name_.empty () && p.age_ == 0);
+      }
+
+      {
+        person p (pq1.execute_value ());
+        assert (p.name_ == "John Doe");
+      }
+    }
   }
   catch (const odb::exception& e)
   {
diff --git a/common/prepared/test.hxx b/common/prepared/test.hxx
index c6e2c1e..571f4b6 100644
--- a/common/prepared/test.hxx
+++ b/common/prepared/test.hxx
@@ -12,9 +12,9 @@
 #pragma db object
 struct person
 {
-  person () {}
+  person (): id_ (0) {}
   person (const std::string& name, unsigned short age)
-      : name_ (name), age_ (age) {}
+      : id_ (0), name_ (name), age_ (age) {}
 
   #pragma db id auto
   unsigned long id_;