--- a/nbproject/project.xml	Sun Dec 02 18:25:43 2018 +0100
+++ b/nbproject/project.xml	Sun Dec 02 20:17:46 2018 +0100
@@ -45,7 +45,7 @@
             <name>relpipe-tr-validator.cpp</name>
             <c-extensions/>
             <cpp-extensions>cpp</cpp-extensions>
-            <header-extensions/>
+            <header-extensions>h</header-extensions>
             <sourceEncoding>UTF-8</sourceEncoding>
             <sourceRootList>
                 <sourceRootElem>.</sourceRootElem>

--- a/src/CMakeLists.txt	Sun Dec 02 18:25:43 2018 +0100
+++ b/src/CMakeLists.txt	Sun Dec 02 20:17:46 2018 +0100
@@ -30,6 +30,7 @@
 # Executable output:
 add_executable(
 	${EXECUTABLE_FILE}
+	PassthroughHandler.h
 	relpipe-tr-validator.cpp
 )
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/PassthroughHandler.h	Sun Dec 02 20:17:46 2018 +0100
@@ -0,0 +1,79 @@
+/**
+ * Relational pipes
+ * Copyright © 2018 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <memory>
+#include <string>
+#include <vector>
+#include <iostream>
+#include <sstream>
+#include <locale>
+#include <codecvt>
+#include <regex>
+
+#include <relpipe/reader/typedefs.h>
+#include <relpipe/reader/TypeId.h>
+#include <relpipe/reader/handlers/RelationalReaderStringHandler.h>
+#include <relpipe/reader/handlers/AttributeMetadata.h>
+
+#include <relpipe/writer/Factory.h>
+
+namespace relpipe {
+namespace tr {
+namespace validator {
+
+using namespace relpipe;
+using namespace relpipe::reader;
+using namespace relpipe::reader::handlers;
+
+// TODO: use rather RelationalReaderStringHadler
+class PassthroughHandler : public RelationalReaderStringHadler {
+private:
+	writer::RelationalWriter* relationalWriter;
+public:
+
+	PassthroughHandler(std::ostream& output) : relationalWriter(writer::Factory::create(output)) {
+	}
+
+	virtual ~PassthroughHandler() {
+		delete relationalWriter;
+	}
+
+	void startRelation(string_t name, std::vector<AttributeMetadata> attributes) override {
+		// TODO: move to a reusable method (or use same metadata on both reader and writer side?)
+		std::vector<writer::AttributeMetadata> writerMetadata;
+		for (AttributeMetadata readerMetadata : attributes) {
+			writerMetadata.push_back({readerMetadata.getAttributeName(), relationalWriter->toTypeId(readerMetadata.getTypeName())});
+		}
+		
+		relationalWriter->startRelation(name, writerMetadata, true);
+	}
+
+	void attribute(const string_t& value) override {
+		relationalWriter->writeAttribute(value);
+	}
+
+	void endOfPipe() {
+
+	}
+
+};
+
+}
+}
+}

--- a/src/relpipe-tr-validator.cpp	Sun Dec 02 18:25:43 2018 +0100
+++ b/src/relpipe-tr-validator.cpp	Sun Dec 02 20:17:46 2018 +0100
@@ -31,8 +31,11 @@
 #include <relpipe/writer/Factory.h>
 #include <relpipe/writer/TypeId.h>
 
+#include "PassthroughHandler.h"
+
 using namespace relpipe::cli;
 using namespace relpipe::reader;
+using namespace relpipe::tr::validator;
 
 int main(int argc, char**argv) {
 	CLI cli(argc, argv);
@@ -41,8 +44,8 @@
 
 	try {
 		std::shared_ptr<RelationalReader> reader(Factory::create(std::cin));
-		//TabularPrefetchingHandler handler(std::cout);
-		//reader->addHandler(&handler);
+		PassthroughHandler handler(std::cout);
+		reader->addHandler(&handler);
 		reader->process();
 
 		resultCode = CLI::EXIT_CODE_SUCCESS;