Updating rows kinda works.

Blocking calls are still used.

pgsql/Pgsql_Connection.cpp

@@ -153,6 +153,18 @@ Result Connection::query(const char * command)
 	return Result(result);
 }
 
+Result Connection::queryParam(const char * command, const Params &params)
+{
+	PGresult *result = PQexecParams(conn, command, params.size(), params.types(),
+						params.values(), params.lengths(), params.formats(), 0);
+	return Result(result);
+}
+
+Result Connection::queryParam(const QString &command, const Params &params)
+{
+	return queryParam(command.toUtf8().data(), params);
+}
+
 
 bool Connection::sendQuery(const char *query)
 {

pgsql/Pgsql_Connection.h

@@ -92,11 +92,15 @@ namespace Pgsql {
 		std::string getErrorMessage() const;
 
 		Result query(const char * command);
+
 		Result query(const QString &command)
 		{
 			return query(command.toUtf8().data());
 		}
 
+		Result queryParam(const char * command, const Params &params);
+		Result queryParam(const QString &command, const Params &params);
+
 		bool sendQuery(const char * query);
 		bool sendQuery(const std::string &command)
 		{

pgsql/Pgsql_Params.h

@@ -5,6 +5,8 @@
 #include <QString>
 #include <libpq-fe.h>
 #include "Pgsql_declare.h"
+#include "Pgsql_oids.h"
+#include <boost/optional.hpp>
 
 namespace Pgsql {
 
@@ -18,8 +20,12 @@ namespace Pgsql {
 		~Params();
 
 
-		void add(const QString &s, Oid oid=VARCHAROID);
-		void add(const char *data, Oid oid=VARCHAROID);
+		void add(const QString &s, Oid oid=varchar_oid);
+		void add(const char *data, Oid oid=varchar_oid);
+		void add(boost::optional<std::string> s, Oid oid=varchar_oid)
+		{
+			add(s ? s->c_str() : nullptr, oid);
+		}
 		//void addBinary(const char *data, int length, Oid oid);
 		void clear();
 

pgsql/Pgsql_Result.cpp

@@ -183,8 +183,10 @@ Value Result::get(int col, int row) const
 	colRangeCheck(col);
 	rowRangeCheck(row);
 
+	bool is_null = PQgetisnull(result, row, col);
+	char *ptr = is_null ? nullptr : PQgetvalue(result, row, col);
 	return Value(
-		PQgetvalue(result, row, col),
+		ptr,
 		PQftype(result, col)
 		);
 }

pgsql/Pgsql_Row.cpp

@@ -33,4 +33,7 @@ Value Row::get(int col) const
 //{
 
 //}
-
+Row::const_iterator Row::end() const
+{
+	return const_iterator(*this, m_result.cols());
+}

pgsql/Pgsql_Row.h

@@ -14,6 +14,51 @@ namespace Pgsql {
 	 */
 	class Row {
 	public:
+		class const_iterator {
+		public:
+			const_iterator(const Row &r, int col)
+				: m_row(r)
+				, m_col(col)
+			{}
+
+			const_iterator operator++()
+			{
+				const_iterator t(*this);
+				++m_col;
+				return t;
+			}
+
+			const_iterator& operator++(int)
+			{
+				++m_col;
+				return *this;
+			}
+
+			bool operator==(const const_iterator &rhs)
+			{
+				return m_row == rhs.m_row && m_col == rhs.m_col;
+			}
+
+			bool operator!=(const const_iterator &rhs)
+			{
+				return !operator==(rhs);
+			}
+
+			const Value operator*()
+			{
+				return m_row.get(m_col);
+			}
+
+			const Value operator->()
+			{
+				return m_row.get(m_col);
+			}
+
+		private:
+			const Row &m_row;
+			int m_col;
+		};
+
 		Row(const Result &result, int row);
 		bool next();
 
@@ -22,6 +67,12 @@ namespace Pgsql {
 		//Value get(const char *colname) const;
 		//bool get(int col, QString &s);
 
+		const_iterator begin() const
+		{
+			return const_iterator(*this, 0);
+		}
+
+		const_iterator end() const;
 
 	private:
 		const Result& m_result;

pgsql/Pgsql_Value.h

@@ -16,9 +16,12 @@ namespace Pgsql {
 	 */
 	class Value {
 	public:
+		const char *empty_str = "";
 		Value(const char *val, Oid typ);
 		QString asQString() const;
-		const char* c_str() const { return m_val; }
+
+		bool null() const { return m_val == nullptr; }
+		const char* c_str() const { return m_val == nullptr ? empty_str : m_val; }
 
 		operator QString() const;
 		operator QDateTime() const;
@@ -42,25 +45,31 @@ namespace Pgsql {
 		template <typename E, typename I>
 		void getAsArray(I insert_iter, NullHandling nullhandling = NullHandling::Throw) const
 		{
-			using value_type = E;
-			ArrayParser parser(m_val);
-			for (;;) {
-				auto res = parser.GetNextElem();
-				if (res.ok) {
-					if (res.value) {
-						std::string str(res.value->data(), res.value->length());
-						Value val(str.c_str(), OidFor<E>::elem());
-						value_type v;
-						v << val;
-						insert_iter = v;
-					}
-					else {
-						if (nullhandling == NullHandling::Throw)
-							throw std::runtime_error("Unexpected NULL value in array");
+			if (m_val == nullptr) {
+				if (nullhandling == NullHandling::Throw)
+					throw std::runtime_error("Unexpected NULL value in array");
+			}
+			else {
+				using value_type = E;
+				ArrayParser parser(m_val);
+				for (;;) {
+					auto res = parser.GetNextElem();
+					if (res.ok) {
+						if (res.value) {
+							std::string str(res.value->data(), res.value->length());
+							Value val(str.c_str(), OidFor<E>::elem());
+							value_type v;
+							v << val;
+							insert_iter = v;
+						}
+						else {
+							if (nullhandling == NullHandling::Throw)
+								throw std::runtime_error("Unexpected NULL value in array");
+						}
 					}
+					else
+						break;
 				}
-				else
-					break;
 			}
 		}