From 521596e38974a68a60dbc8eb083cc881bb11914f Mon Sep 17 00:00:00 2001
From: Michael Shepanski <michael@codesynthesis.com>
Date: Tue, 4 Nov 2014 16:10:03 +1100
Subject: 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).
---
 odb/pgsql/database.hxx |  62 +++++++++++++++++++++++++
 odb/pgsql/database.ixx | 120 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 182 insertions(+)

diff --git a/odb/pgsql/database.hxx b/odb/pgsql/database.hxx
index 2a70e96..dda8d31 100644
--- a/odb/pgsql/database.hxx
+++ b/odb/pgsql/database.hxx
@@ -288,6 +288,68 @@ namespace odb
       result<T>
       query (const odb::query_base&);
 
+      // Query one API.
+      //
+      template <typename T>
+      typename object_traits<T>::pointer_type
+      query_one ();
+
+      template <typename T>
+      bool
+      query_one (T& object);
+
+      template <typename T>
+      T
+      query_value ();
+
+      template <typename T>
+      typename object_traits<T>::pointer_type
+      query_one (const char*);
+
+      template <typename T>
+      bool
+      query_one (const char*, T& object);
+
+      template <typename T>
+      T
+      query_value (const char*);
+
+      template <typename T>
+      typename object_traits<T>::pointer_type
+      query_one (const std::string&);
+
+      template <typename T>
+      bool
+      query_one (const std::string&, T& object);
+
+      template <typename T>
+      T
+      query_value (const std::string&);
+
+      template <typename T>
+      typename object_traits<T>::pointer_type
+      query_one (const pgsql::query_base&);
+
+      template <typename T>
+      bool
+      query_one (const pgsql::query_base&, T& object);
+
+      template <typename T>
+      T
+      query_value (const pgsql::query_base&);
+
+      template <typename T>
+      typename object_traits<T>::pointer_type
+      query_one (const odb::query_base&);
+
+      template <typename T>
+      bool
+      query_one (const odb::query_base&, T& object);
+
+      template <typename T>
+      T
+      query_value (const odb::query_base&);
+
       // Query preparation.
       //
       template <typename T>
diff --git a/odb/pgsql/database.ixx b/odb/pgsql/database.ixx
index 809e4d4..21b5729 100644
--- a/odb/pgsql/database.ixx
+++ b/odb/pgsql/database.ixx
@@ -429,6 +429,126 @@ namespace odb
     }
 
     template <typename T>
+    inline typename object_traits<T>::pointer_type database::
+    query_one ()
+    {
+      return query_one<T> (pgsql::query_base ());
+    }
+
+    template <typename T>
+    inline bool database::
+    query_one (T& o)
+    {
+      return query_one<T> (pgsql::query_base (), o);
+    }
+
+    template <typename T>
+    inline T database::
+    query_value ()
+    {
+      return query_value<T> (pgsql::query_base ());
+    }
+
+    template <typename T>
+    inline typename object_traits<T>::pointer_type database::
+    query_one (const char* q)
+    {
+      return query_one<T> (pgsql::query_base (q));
+    }
+
+    template <typename T>
+    inline bool database::
+    query_one (const char* q, T& o)
+    {
+      return query_one<T> (pgsql::query_base (q), o);
+    }
+
+    template <typename T>
+    inline T database::
+    query_value (const char* q)
+    {
+      return query_value<T> (pgsql::query_base (q));
+    }
+
+    template <typename T>
+    inline typename object_traits<T>::pointer_type database::
+    query_one (const std::string& q)
+    {
+      return query_one<T> (pgsql::query_base (q));
+    }
+
+    template <typename T>
+    inline bool database::
+    query_one (const std::string& q, T& o)
+    {
+      return query_one<T> (pgsql::query_base (q), o);
+    }
+
+    template <typename T>
+    inline T database::
+    query_value (const std::string& q)
+    {
+      return query_value<T> (pgsql::query_base (q));
+    }
+
+    template <typename T>
+    inline typename object_traits<T>::pointer_type database::
+    query_one (const pgsql::query_base& q)
+    {
+      // T is always object_type. We also don't need to check for transaction
+      // here; object_traits::query () does this.
+      //
+      return query_one_<T, id_pgsql> (q);
+    }
+
+    template <typename T>
+    inline bool database::
+    query_one (const pgsql::query_base& q, T& o)
+    {
+      // T is always object_type. We also don't need to check for transaction
+      // here; object_traits::query () does this.
+      //
+      return query_one_<T, id_pgsql> (q, o);
+    }
+
+    template <typename T>
+    inline T database::
+    query_value (const pgsql::query_base& q)
+    {
+      // T is always object_type. We also don't need to check for transaction
+      // here; object_traits::query () does this.
+      //
+      return query_value_<T, id_pgsql> (q);
+    }
+
+    template <typename T>
+    inline typename object_traits<T>::pointer_type database::
+    query_one (const odb::query_base& q)
+    {
+      // Translate to native query.
+      //
+      return query_one<T> (pgsql::query_base (q));
+    }
+
+    template <typename T>
+    inline bool database::
+    query_one (const odb::query_base& q, T& o)
+    {
+      // Translate to native query.
+      //
+      return query_one<T> (pgsql::query_base (q), o);
+    }
+
+    template <typename T>
+    inline T database::
+    query_value (const odb::query_base& q)
+    {
+      // Translate to native query.
+      //
+      return query_value<T> (pgsql::query_base (q));
+    }
+
+    template <typename T>
     inline prepared_query<T> database::
     prepare_query (const char* n, const char* q)
     {
-- 
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