From 3b7c88c73b45349b84df2f85a5da2a4c65e9826c Mon Sep 17 00:00:00 2001
From: "Dr. Patrick Urbanke" <patrick@getml.com>
Date: Wed, 9 Apr 2025 09:20:54 +0200
Subject: [PATCH] Added to_select_from

---
 include/sqlgen/dynamic/Statement.hpp |  3 ++-
 include/sqlgen/sqlite/Connection.hpp |  3 +++
 src/sqlgen/sqlite/Connection.cpp     | 24 ++++++++++++++++++++++++
 tests/sqlite/test_to_select_from.cpp | 24 ++++++++++++++++++++++++
 4 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 tests/sqlite/test_to_select_from.cpp

diff --git a/include/sqlgen/dynamic/Statement.hpp b/include/sqlgen/dynamic/Statement.hpp
index f9803ab..20ed123 100644
--- a/include/sqlgen/dynamic/Statement.hpp
+++ b/include/sqlgen/dynamic/Statement.hpp
@@ -5,10 +5,11 @@
 
 #include "CreateTable.hpp"
 #include "Insert.hpp"
+#include "SelectFrom.hpp"
 
 namespace sqlgen::dynamic {
 
-using Statement = rfl::TaggedUnion<"stmt", CreateTable, Insert>;
+using Statement = rfl::TaggedUnion<"stmt", CreateTable, Insert, SelectFrom>;
 
 }  // namespace sqlgen::dynamic
 
diff --git a/include/sqlgen/sqlite/Connection.hpp b/include/sqlgen/sqlite/Connection.hpp
index 53f9e57..51fc971 100644
--- a/include/sqlgen/sqlite/Connection.hpp
+++ b/include/sqlgen/sqlite/Connection.hpp
@@ -64,6 +64,9 @@ class Connection : public sqlgen::Connection {
   /// Expresses the properies as SQL.
   std::string properties_to_sql(const dynamic::types::Properties& _p) noexcept;
 
+  /// Transforms an Insert Statement to an SQL string.
+  std::string select_from_to_sql(const dynamic::SelectFrom& _stmt) noexcept;
+
   /// Expresses the type as SQL.
   std::string type_to_sql(const dynamic::Type& _type) noexcept;
 
diff --git a/src/sqlgen/sqlite/Connection.cpp b/src/sqlgen/sqlite/Connection.cpp
index efe5da0..1be50dd 100644
--- a/src/sqlgen/sqlite/Connection.cpp
+++ b/src/sqlgen/sqlite/Connection.cpp
@@ -119,12 +119,36 @@ std::string Connection::to_sql(const dynamic::Statement& _stmt) noexcept {
       return create_table_to_sql(_s);
     } else if constexpr (std::is_same_v<S, dynamic::Insert>) {
       return insert_to_sql(_s);
+    } else if constexpr (std::is_same_v<S, dynamic::SelectFrom>) {
+      return select_from_to_sql(_s);
     } else {
       static_assert(rfl::always_false_v<S>, "Unsupported type.");
     }
   });
 }
 
+std::string Connection::select_from_to_sql(
+    const dynamic::SelectFrom& _stmt) noexcept {
+  using namespace std::ranges::views;
+
+  const auto to_str = [](const auto& _col) -> std::string {
+    return "\"" + _col.name + "\"";
+  };
+
+  std::stringstream stream;
+  stream << "SELECT ";
+  stream << internal::strings::join(
+      ", ", internal::collect::vector(_stmt.columns | transform(to_str)));
+
+  stream << " FROM ";
+  if (_stmt.table.schema) {
+    stream << "\"" << *_stmt.table.schema << "\".";
+  }
+  stream << "\"" << _stmt.table.name << "\";";
+
+  return stream.str();
+}
+
 Result<Nothing> Connection::start_write(const dynamic::Insert& _stmt) {
   if (stmt_) {
     return error(
diff --git a/tests/sqlite/test_to_select_from.cpp b/tests/sqlite/test_to_select_from.cpp
new file mode 100644
index 0000000..af64058
--- /dev/null
+++ b/tests/sqlite/test_to_select_from.cpp
@@ -0,0 +1,24 @@
+#include <gtest/gtest.h>
+
+#include <sqlgen.hpp>
+#include <sqlgen/parsing/to_select_from.hpp>
+#include <sqlgen/sqlite.hpp>
+
+namespace test_to_select_from {
+
+struct TestTable {
+  std::string field1;
+  int32_t field2;
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::optional<std::string> nullable;
+};
+
+TEST(sqlite, test_to_select_from) {
+  const auto select_from_stmt = sqlgen::parsing::to_select_from<TestTable>();
+  const auto conn = sqlgen::sqlite::connect().value();
+  const auto expected =
+      R"(SELECT "field1", "field2", "id", "nullable" FROM "TestTable";)";
+
+  EXPECT_EQ(conn->to_sql(select_from_stmt), expected);
+}
+}  // namespace test_to_select_from