From a032632f68905543d21d1c279176e001f38d6fcb Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 8 Nov 2015 15:53:35 +0000
Subject: Support extracting nullable fields into boost::optional<T>s

---
 libdbpp/column.h                | 11 +++++++++++
 libdbpp/unittests/testUtils.cpp | 16 ++++++++++++++++
 libdbpp/unittests/util.sql      |  1 +
 3 files changed, 28 insertions(+)

diff --git a/libdbpp/column.h b/libdbpp/column.h
index 37f3b88..43d2687 100644
--- a/libdbpp/column.h
+++ b/libdbpp/column.h
@@ -4,6 +4,7 @@
 #include <glibmm/ustring.h>
 #include <boost/date_time/posix_time/posix_time_types.hpp>
 #include <boost/shared_ptr.hpp>
+#include <boost/optional.hpp>
 #include <visibility.h>
 
 namespace DB {
@@ -53,6 +54,16 @@ namespace DB {
 			void operator>>(boost::posix_time::time_duration &) const;
 			/// STL like date time extractor.
 			void operator>>(boost::posix_time::ptime &) const;
+			template <typename T>
+			void operator>>(boost::optional<T> & v) const {
+				if (!isNull()) {
+					v = T();
+					operator>>(v.get());
+				}
+				else {
+					v = boost::none;
+				}
+			}
 
 			/// This column's ordinal.
 			const unsigned int		colNo;
diff --git a/libdbpp/unittests/testUtils.cpp b/libdbpp/unittests/testUtils.cpp
index e43faae..b7947c7 100644
--- a/libdbpp/unittests/testUtils.cpp
+++ b/libdbpp/unittests/testUtils.cpp
@@ -33,6 +33,22 @@ BOOST_AUTO_TEST_CASE( forEachRow )
 			});
 }
 
+BOOST_AUTO_TEST_CASE( forEachRowNulls )
+{
+	auto db = DB::ConnectionPtr(DB::MockDatabase::openConnectionTo("pqmock"));
+	auto sel = DB::SelectCommandPtr(db->newSelectCommand("SELECT a, b, c, d, e, f FROM forEachRow ORDER BY a DESC LIMIT 1"));
+	sel->forEachRow<int64_t, boost::optional<double>, std::string, boost::optional<boost::posix_time::ptime>, boost::optional<boost::posix_time::time_duration>, bool>(
+			[](auto a, auto b, auto c, auto d, auto e, auto f) {
+				BOOST_REQUIRE_EQUAL(2, a);
+				BOOST_REQUIRE(b);
+				BOOST_REQUIRE_EQUAL(2.3, *b);
+				BOOST_REQUIRE_EQUAL("Some text", c);
+				BOOST_REQUIRE(!d);
+				BOOST_REQUIRE(!e);
+				BOOST_REQUIRE_EQUAL(false, f);
+			});
+}
+
 BOOST_AUTO_TEST_CASE( execute )
 {
 	auto db = DB::ConnectionPtr(DB::MockDatabase::openConnectionTo("pqmock"));
diff --git a/libdbpp/unittests/util.sql b/libdbpp/unittests/util.sql
index fe98fc9..04c6bf6 100644
--- a/libdbpp/unittests/util.sql
+++ b/libdbpp/unittests/util.sql
@@ -6,4 +6,5 @@ CREATE TABLE foreachrow (
 		e interval,
 		f boolean);
 INSERT INTO foreachrow(a, b, c, d, e, f) VALUES(1, 2.3, 'Some text', '2015-11-07 13:39:17', '04:03:02', true);
+INSERT INTO foreachrow(a, b, c, f) VALUES(2, 2.3, 'Some text', false);
 
-- 
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