Added sqlgen::Flatten

tests/sqlite/test_flatten.cpp

@@ -0,0 +1,45 @@
+#include <gtest/gtest.h>
+
+#include <rfl.hpp>
+#include <rfl/json.hpp>
+#include <sqlgen.hpp>
+#include <sqlgen/sqlite.hpp>
+#include <vector>
+
+namespace test_write_and_read {
+
+struct Person {
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::string first_name;
+  std::string last_name;
+  int age;
+};
+
+struct Employee {
+  static constexpr const char* tablename = "EMPLOYEES";
+
+  sqlgen::Flatten<Person> person;
+  float salary;
+};
+
+TEST(sqlite, test_flatten) {
+  const auto people1 =
+      std::vector<Employee>({Employee{.person = Person{.id = 0,
+                                                       .first_name = "Homer",
+                                                       .last_name = "Simpson",
+                                                       .age = 45},
+                                      .salary = 60000.0}});
+
+  const auto conn = sqlgen::sqlite::connect();
+
+  sqlgen::write(conn, people1);
+
+  const auto people2 = sqlgen::read<std::vector<Employee>>(conn).value();
+
+  const auto json1 = rfl::json::write(people1);
+  const auto json2 = rfl::json::write(people2);
+
+  EXPECT_EQ(json1, json2);
+}
+
+}  // namespace test_write_and_read