From 15c1e5566f7ad8448985ca6e52805ceb4ec389a8 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 24 May 2021 01:01:30 +0100
Subject: Basic support for queries with bound parameters

Bit of a reshuffle to make the types not DB specific, add some basic tests over query
execution, no selects yet and no validation anything is actually right.
---
 lib/output/pq/pqConn.cpp | 70 ++++++++++++++++++++++++++++++++++++++++++++++++
 lib/output/pq/pqConn.h   |  8 +++++-
 2 files changed, 77 insertions(+), 1 deletion(-)

(limited to 'lib/output')

diff --git a/lib/output/pq/pqConn.cpp b/lib/output/pq/pqConn.cpp
index 78cdc06..4f55ba8 100644
--- a/lib/output/pq/pqConn.cpp
+++ b/lib/output/pq/pqConn.cpp
@@ -1,8 +1,17 @@
 #include "pqConn.h"
+#include <dbTypes.h>
 #include <helpers.h>
+#include <libpq-fe.h>
+#include <memory>
+#include <sstream>
 #include <stdexcept>
+#include <string>
+#include <variant>
+#include <vector>
 
 namespace MyGrate::Output::Pq {
+	using ResPtr = std::unique_ptr<PGresult, decltype(&PQclear)>;
+
 	PqConn::PqConn(const char * const str) : conn {PQconnectdb(str)}
 	{
 		verify<std::runtime_error>(PQstatus(conn) == CONNECTION_OK, "Connection failure");
@@ -14,6 +23,67 @@ namespace MyGrate::Output::Pq {
 		PQfinish(conn);
 	}
 
+	void
+	PqConn::query(const char * const q)
+	{
+		ResPtr res {PQexec(conn, q), &PQclear};
+		verify<std::runtime_error>(PQresultStatus(res.get()) == PGRES_COMMAND_OK, q);
+	}
+
+	struct Bindings {
+		// NOLINTNEXTLINE(hicpp-explicit-conversions)
+		explicit Bindings(const std::initializer_list<DbValue> & vs)
+		{
+			bufs.reserve(vs.size());
+			values.reserve(vs.size());
+			lengths.reserve(vs.size());
+			for (const auto & v : vs) {
+				std::visit(*this, v);
+			}
+		}
+		template<Stringable T>
+		void
+		operator()(const T & v)
+		{
+			bufs.emplace_back(std::to_string(v));
+			const auto & vw {bufs.back()};
+			values.emplace_back(vw.data());
+			lengths.emplace_back(vw.length());
+		}
+		template<Viewable T>
+		void
+		operator()(const T & v)
+		{
+			values.emplace_back(v.data());
+			lengths.emplace_back(v.size());
+		}
+		template<typename T>
+		void
+		operator()(const T &)
+		{
+			throw std::runtime_error("Not implemented");
+		}
+		void
+		operator()(const std::nullptr_t &)
+		{
+			values.emplace_back(nullptr);
+			lengths.emplace_back(0);
+		}
+
+		std::vector<std::string> bufs;
+		std::vector<const char *> values;
+		std::vector<int> lengths;
+	};
+
+	void
+	PqConn::query(const char * const q, const std::initializer_list<DbValue> & vs)
+	{
+		Bindings b {vs};
+		ResPtr res {PQexecParams(conn, q, (int)vs.size(), nullptr, b.values.data(), b.lengths.data(), nullptr, 0),
+				&PQclear};
+		verify<std::runtime_error>(PQresultStatus(res.get()) == PGRES_COMMAND_OK, q);
+	}
+
 	void
 	PqConn::notice_processor(void * p, const char * n)
 	{
diff --git a/lib/output/pq/pqConn.h b/lib/output/pq/pqConn.h
index bcf30b6..613af6f 100644
--- a/lib/output/pq/pqConn.h
+++ b/lib/output/pq/pqConn.h
@@ -1,14 +1,20 @@
 #ifndef MYGRATE_OUTPUT_PQ_PQCONN_H
 #define MYGRATE_OUTPUT_PQ_PQCONN_H
 
+#include <dbConn.h>
+#include <dbTypes.h>
+#include <initializer_list>
 #include <libpq-fe.h>
 
 namespace MyGrate::Output::Pq {
-	class PqConn {
+	class PqConn : public DbConn {
 	public:
 		explicit PqConn(const char * const str);
 		virtual ~PqConn();
 
+		void query(const char * const) override;
+		void query(const char * const, const std::initializer_list<DbValue> &) override;
+
 	private:
 		static void notice_processor(void *, const char *);
 		virtual void notice_processor(const char *) const;
-- 
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