null support | header + test

hdr/sqlite_modern_cpp/extensions/null_support.h

@@ -0,0 +1,33 @@
+#pragma once
+
+using namespace sqlite;
+using namespace std;
+
+namespace sqlite {
+	// custom null value
+	struct null_value {
+		bool value = true;
+		void operator=(bool val) { value = val; }
+		operator bool() const { return value; }
+	};
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-variable"
+	template<> inline database_binder::chain_type& operator <<(database_binder::chain_type& db, const sqlite::null_value& val) {
+		int hresult;
+		if((hresult = sqlite3_bind_null(db->_stmt.get(), db->_inx)) != SQLITE_OK) {
+			exceptions::throw_sqlite_error(hresult);
+		}
+		++db->_inx;
+		return db;
+	}
+#pragma GCC diagnostic pop
+
+	template<> inline void get_col_from_db(database_binder& db, int inx, sqlite::null_value& d) {
+		if(sqlite3_column_type(db._stmt.get(), inx) == SQLITE_NULL) {
+			d = true;
+		} else {
+			d = false;
+		}
+	}
+}

tests/null_value.cc

@@ -0,0 +1,35 @@
+#include <iostream>
+#include <string>
+#include <sqlite_modern_cpp.h>
+#include <sqlite_modern_cpp/extensions/null_support.h>
+
+int main() {
+
+	try {
+		database db(":memory:");
+		db << "CREATE TABLE tbl (id integer, name string);";
+		db << "INSERT INTO tbl VALUES (?, ?);" << 1 << "hello";
+		db << "INSERT INTO tbl VALUES (?, ?);" << 2 << null_value();
+
+		db << "select id,name from tbl where id = 1" >> [](int id, null_value name_null) {
+			cout << "Name should not be null for ID:" << id;
+			if(name_null) exit(EXIT_FAILURE);
+		};
+
+		db << "select id,name from tbl where id = 2" >> [](int id, null_value name_null) {
+			cout << "Name should be null for ID:" << id;
+			if(!name_null) exit(EXIT_FAILURE);
+		};
+
+
+	} catch(sqlite_exception e) {
+		cout << "Sqlite error " << e.what() << endl;
+		exit(EXIT_FAILURE);
+	} catch(...) {
+		cout << "Unknown error\n";
+		exit(EXIT_FAILURE);
+	}
+
+	cout << "OK\n";
+	exit(EXIT_SUCCESS);
+}