From 9d6cac05026bbca0790c90c674ffad8a3ec274c3 Mon Sep 17 00:00:00 2001
From: "Dr. Patrick Urbanke" <patrick@getml.com>
Date: Sun, 11 May 2025 05:15:04 +0200
Subject: [PATCH] Added update

---
 include/sqlgen.hpp                         |  1 +
 include/sqlgen/col.hpp                     | 12 ++++
 include/sqlgen/dynamic/Statement.hpp       |  5 +-
 include/sqlgen/dynamic/Update.hpp          | 27 +++++++++
 include/sqlgen/transpilation/Set.hpp       | 15 +++++
 include/sqlgen/transpilation/to_sets.hpp   | 69 ++++++++++++++++++++++
 include/sqlgen/transpilation/to_sql.hpp    |  9 +++
 include/sqlgen/transpilation/to_update.hpp | 31 ++++++++++
 include/sqlgen/update.hpp                  | 54 +++++++++++++++++
 include/sqlgen/where.hpp                   | 11 ++++
 src/sqlgen/postgres/to_sql.cpp             | 37 ++++++++++++
 src/sqlgen/sqlite/to_sql.cpp               | 37 ++++++++++++
 tests/postgres/test_update_dry.cpp         | 27 +++++++++
 tests/sqlite/test_update.cpp               | 51 ++++++++++++++++
 14 files changed, 384 insertions(+), 2 deletions(-)
 create mode 100644 include/sqlgen/dynamic/Update.hpp
 create mode 100644 include/sqlgen/transpilation/Set.hpp
 create mode 100644 include/sqlgen/transpilation/to_sets.hpp
 create mode 100644 include/sqlgen/transpilation/to_update.hpp
 create mode 100644 include/sqlgen/update.hpp
 create mode 100644 tests/postgres/test_update_dry.cpp
 create mode 100644 tests/sqlite/test_update.cpp

diff --git a/include/sqlgen.hpp b/include/sqlgen.hpp
index 923ed6f..eb71aca 100644
--- a/include/sqlgen.hpp
+++ b/include/sqlgen.hpp
@@ -22,6 +22,7 @@
 #include "sqlgen/order_by.hpp"
 #include "sqlgen/patterns.hpp"
 #include "sqlgen/read.hpp"
+#include "sqlgen/update.hpp"
 #include "sqlgen/where.hpp"
 #include "sqlgen/write.hpp"
 
diff --git a/include/sqlgen/col.hpp b/include/sqlgen/col.hpp
index 9fc996c..7d3c307 100644
--- a/include/sqlgen/col.hpp
+++ b/include/sqlgen/col.hpp
@@ -6,6 +6,7 @@
 
 #include "transpilation/Condition.hpp"
 #include "transpilation/Desc.hpp"
+#include "transpilation/Set.hpp"
 #include "transpilation/Value.hpp"
 #include "transpilation/conditions.hpp"
 
@@ -20,6 +21,17 @@ struct Col {
 
   /// Returns the column name.
   std::string name() const noexcept { return Name().str(); }
+
+  /// Defines a SET clause in an UPDATE statement.
+  template <class T>
+  auto set(const T& _to) const noexcept {
+    return transpilation::Set<Col<_name>, std::remove_cvref_t<T>>{.to = _to};
+  }
+
+  /// Defines a SET clause in an UPDATE statement.
+  auto set(const char* _to) const noexcept {
+    return transpilation::Set<Col<_name>, std::string>{.to = _to};
+  }
 };
 
 template <rfl::internal::StringLiteral _name>
diff --git a/include/sqlgen/dynamic/Statement.hpp b/include/sqlgen/dynamic/Statement.hpp
index 4ada452..290fa62 100644
--- a/include/sqlgen/dynamic/Statement.hpp
+++ b/include/sqlgen/dynamic/Statement.hpp
@@ -8,11 +8,12 @@
 #include "Drop.hpp"
 #include "Insert.hpp"
 #include "SelectFrom.hpp"
+#include "Update.hpp"
 
 namespace sqlgen::dynamic {
 
-using Statement =
-    rfl::TaggedUnion<"stmt", CreateTable, DeleteFrom, Drop, Insert, SelectFrom>;
+using Statement = rfl::TaggedUnion<"stmt", CreateTable, DeleteFrom, Drop,
+                                   Insert, SelectFrom, Update>;
 
 }  // namespace sqlgen::dynamic
 
diff --git a/include/sqlgen/dynamic/Update.hpp b/include/sqlgen/dynamic/Update.hpp
new file mode 100644
index 0000000..33cf782
--- /dev/null
+++ b/include/sqlgen/dynamic/Update.hpp
@@ -0,0 +1,27 @@
+#ifndef SQLGEN_DYNAMIC_UPDATE_HPP_
+#define SQLGEN_DYNAMIC_UPDATE_HPP_
+
+#include <optional>
+#include <vector>
+
+#include "Column.hpp"
+#include "ColumnOrValue.hpp"
+#include "Condition.hpp"
+#include "Table.hpp"
+
+namespace sqlgen::dynamic {
+
+struct Update {
+  struct Set {
+    Column col;
+    ColumnOrValue to;
+  };
+
+  Table table;
+  std::vector<Set> sets;
+  std::optional<Condition> where;
+};
+
+}  // namespace sqlgen::dynamic
+
+#endif
diff --git a/include/sqlgen/transpilation/Set.hpp b/include/sqlgen/transpilation/Set.hpp
new file mode 100644
index 0000000..5e59cb6
--- /dev/null
+++ b/include/sqlgen/transpilation/Set.hpp
@@ -0,0 +1,15 @@
+#ifndef SQLGEN_TRANSPILATION_SET_HPP_
+#define SQLGEN_TRANSPILATION_SET_HPP_
+
+namespace sqlgen::transpilation {
+
+/// Defines the SET clause in an UPDATE statement.
+template <class _ColType, class T>
+struct Set {
+  using ColType = _ColType;
+  T to;
+};
+
+}  // namespace sqlgen::transpilation
+
+#endif
diff --git a/include/sqlgen/transpilation/to_sets.hpp b/include/sqlgen/transpilation/to_sets.hpp
new file mode 100644
index 0000000..4461e88
--- /dev/null
+++ b/include/sqlgen/transpilation/to_sets.hpp
@@ -0,0 +1,69 @@
+#ifndef SQLGEN_TRANSPILATION_TO_SETS_HPP_
+#define SQLGEN_TRANSPILATION_TO_SETS_HPP_
+
+#include <rfl.hpp>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#include "../Result.hpp"
+#include "../col.hpp"
+#include "../dynamic/Table.hpp"
+#include "../dynamic/Update.hpp"
+#include "Set.hpp"
+#include "all_columns_exist.hpp"
+#include "get_schema.hpp"
+#include "get_tablename.hpp"
+#include "to_condition.hpp"
+#include "to_sets.hpp"
+#include "to_value.hpp"
+
+namespace sqlgen::transpilation {
+
+template <class T, class SetType>
+struct ToSet;
+
+template <class T, rfl::internal::StringLiteral _name, class ToType>
+struct ToSet<T, Set<Col<_name>, ToType>> {
+  static_assert(all_columns_exist<T, Col<_name>>(), "All columns must exist.");
+
+  dynamic::Update::Set operator()(const auto& _set) const {
+    return dynamic::Update::Set{
+        .col = dynamic::Column{.name = _name.str()},
+        .to = to_value(_set.to),
+    };
+  }
+};
+
+template <class T, rfl::internal::StringLiteral _name1,
+          rfl::internal::StringLiteral _name2>
+struct ToSet<T, Set<Col<_name1>, Col<_name2>>> {
+  static_assert(all_columns_exist<T, Col<_name1>>(), "All columns must exist.");
+  static_assert(all_columns_exist<T, Col<_name2>>(), "All columns must exist.");
+
+  dynamic::Update::Set operator()(const auto& _set) const {
+    return dynamic::Update::Set{
+        .col = dynamic::Column{.name = _name1.str()},
+        .to = dynamic::Column{.name = _name2.str()},
+    };
+  }
+};
+
+template <class T, class SetType>
+dynamic::Update::Set to_set(const SetType& _set) {
+  return ToSet<std::remove_cvref_t<T>, std::remove_cvref_t<SetType>>{}(_set);
+}
+
+template <class T, class SetsType>
+std::vector<dynamic::Update::Set> to_sets(const SetsType& _sets) {
+  return rfl::apply(
+      [](const auto&... _s) {
+        return std::vector<dynamic::Update::Set>({to_set<T>(_s)...});
+      },
+      _sets);
+}
+
+}  // namespace sqlgen::transpilation
+
+#endif
diff --git a/include/sqlgen/transpilation/to_sql.hpp b/include/sqlgen/transpilation/to_sql.hpp
index 6855a55..80b0c78 100644
--- a/include/sqlgen/transpilation/to_sql.hpp
+++ b/include/sqlgen/transpilation/to_sql.hpp
@@ -9,11 +9,13 @@
 #include "../drop.hpp"
 #include "../dynamic/Statement.hpp"
 #include "../read.hpp"
+#include "../update.hpp"
 #include "to_create_table.hpp"
 #include "to_delete_from.hpp"
 #include "to_drop.hpp"
 #include "to_insert.hpp"
 #include "to_select_from.hpp"
+#include "to_update.hpp"
 #include "value_t.hpp"
 
 namespace sqlgen::transpilation {
@@ -56,6 +58,13 @@ struct ToSQL<Read<ContainerType, WhereType, OrderByType, LimitType>> {
   }
 };
 
+template <class T, class SetsType, class WhereType>
+struct ToSQL<Update<T, SetsType, WhereType>> {
+  dynamic::Statement operator()(const auto& _update) const {
+    return to_update<T, SetsType, WhereType>(_update.sets_, _update.where_);
+  }
+};
+
 template <class T>
 dynamic::Statement to_sql(const T& _t) {
   return ToSQL<std::remove_cvref_t<T>>{}(_t);
diff --git a/include/sqlgen/transpilation/to_update.hpp b/include/sqlgen/transpilation/to_update.hpp
new file mode 100644
index 0000000..9ecceb5
--- /dev/null
+++ b/include/sqlgen/transpilation/to_update.hpp
@@ -0,0 +1,31 @@
+#ifndef SQLGEN_TRANSPILATION_TO_UPDATE_HPP_
+#define SQLGEN_TRANSPILATION_TO_UPDATE_HPP_
+
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#include "../Result.hpp"
+#include "../dynamic/Table.hpp"
+#include "../dynamic/Update.hpp"
+#include "get_schema.hpp"
+#include "get_tablename.hpp"
+#include "to_condition.hpp"
+#include "to_sets.hpp"
+
+namespace sqlgen::transpilation {
+
+template <class T, class SetsType, class WhereType>
+  requires std::is_class_v<std::remove_cvref_t<T>> &&
+           std::is_aggregate_v<std::remove_cvref_t<T>>
+dynamic::Update to_update(const SetsType& _sets, const WhereType& _where) {
+  return dynamic::Update{.table = dynamic::Table{.name = get_tablename<T>(),
+                                                 .schema = get_schema<T>()},
+                         .sets = to_sets<T>(_sets),
+                         .where = to_condition<std::remove_cvref_t<T>>(_where)};
+}
+
+}  // namespace sqlgen::transpilation
+
+#endif
diff --git a/include/sqlgen/update.hpp b/include/sqlgen/update.hpp
new file mode 100644
index 0000000..5944a27
--- /dev/null
+++ b/include/sqlgen/update.hpp
@@ -0,0 +1,54 @@
+#ifndef SQLGEN_UPDATE_HPP_
+#define SQLGEN_UPDATE_HPP_
+
+#include <rfl.hpp>
+#include <type_traits>
+
+#include "Connection.hpp"
+#include "Ref.hpp"
+#include "Result.hpp"
+#include "transpilation/to_update.hpp"
+
+namespace sqlgen {
+
+template <class ValueType, class SetsType, class WhereType>
+Result<Nothing> update_impl(const Ref<Connection>& _conn, const SetsType& _sets,
+                            const WhereType& _where) {
+  const auto query =
+      transpilation::to_update<ValueType, SetsType, WhereType>(_sets, _where);
+  return _conn->execute(_conn->to_sql(query));
+}
+
+template <class ValueType, class SetsType, class WhereType>
+Result<Nothing> update_impl(const Result<Ref<Connection>>& _res,
+                            const SetsType& _sets, const WhereType& _where) {
+  return _res.and_then([&](const auto& _conn) {
+    return update_impl<ValueType, SetsType, WhereType>(_conn, _sets, _where);
+  });
+}
+
+template <class ValueType, class SetsType, class WhereType = Nothing>
+struct Update {
+  Result<Nothing> operator()(const auto& _conn) const noexcept {
+    try {
+      return update_impl<ValueType, SetsType, WhereType>(_conn, sets_, where_);
+    } catch (std::exception& e) {
+      return error(e.what());
+    }
+  }
+
+  SetsType sets_;
+
+  WhereType where_;
+};
+
+template <class ValueType, class... SetsType>
+inline auto update(const SetsType&... _sets) {
+  static_assert(sizeof...(_sets) > 0, "You must update at least one column.");
+  using TupleType = rfl::Tuple<std::remove_cvref_t<SetsType>...>;
+  return Update<ValueType, TupleType>{.sets_ = TupleType(_sets...)};
+};
+
+}  // namespace sqlgen
+
+#endif
diff --git a/include/sqlgen/where.hpp b/include/sqlgen/where.hpp
index 0cf36d0..1c64a67 100644
--- a/include/sqlgen/where.hpp
+++ b/include/sqlgen/where.hpp
@@ -8,6 +8,7 @@
 #include "read.hpp"
 #include "transpilation/Limit.hpp"
 #include "transpilation/value_t.hpp"
+#include "update.hpp"
 
 namespace sqlgen {
 
@@ -40,6 +41,16 @@ auto operator|(const Read<ContainerType, WhereType, OrderByType, LimitType>& _r,
       .where_ = _where.condition};
 }
 
+template <class ValueType, class SetsType, class WhereType, class ConditionType>
+auto operator|(const Update<ValueType, SetsType, WhereType>& _u,
+               const Where<ConditionType>& _where) {
+  static_assert(std::is_same_v<WhereType, Nothing>,
+                "You cannot call where(...) twice (but you can apply more "
+                "than one condition by combining them with && or ||).");
+  return Update<ValueType, SetsType, ConditionType>{.sets_ = _u.sets_,
+                                                    .where_ = _where.condition};
+}
+
 template <class ConditionType>
 inline auto where(const ConditionType& _cond) {
   return Where<std::remove_cvref_t<ConditionType>>{.condition = _cond};
diff --git a/src/sqlgen/postgres/to_sql.cpp b/src/sqlgen/postgres/to_sql.cpp
index ecbab73..bf6a74b 100644
--- a/src/sqlgen/postgres/to_sql.cpp
+++ b/src/sqlgen/postgres/to_sql.cpp
@@ -37,6 +37,8 @@ std::string select_from_to_sql(const dynamic::SelectFrom& _stmt) noexcept;
 
 std::string type_to_sql(const dynamic::Type& _type) noexcept;
 
+std::string update_to_sql(const dynamic::Update& _stmt) noexcept;
+
 // ----------------------------------------------------------------------------
 
 inline std::string get_name(const dynamic::Column& _col) { return _col.name; }
@@ -268,6 +270,7 @@ std::string select_from_to_sql(const dynamic::SelectFrom& _stmt) noexcept {
 std::string to_sql_impl(const dynamic::Statement& _stmt) noexcept {
   return _stmt.visit([&](const auto& _s) -> std::string {
     using S = std::remove_cvref_t<decltype(_s)>;
+
     if constexpr (std::is_same_v<S, dynamic::CreateTable>) {
       return create_table_to_sql(_s);
 
@@ -283,6 +286,9 @@ std::string to_sql_impl(const dynamic::Statement& _stmt) noexcept {
     } else if constexpr (std::is_same_v<S, dynamic::SelectFrom>) {
       return select_from_to_sql(_s);
 
+    } else if constexpr (std::is_same_v<S, dynamic::Update>) {
+      return update_to_sql(_s);
+
     } else {
       static_assert(rfl::always_false_v<S>, "Unsupported type.");
     }
@@ -325,4 +331,35 @@ std::string type_to_sql(const dynamic::Type& _type) noexcept {
   });
 }
 
+std::string update_to_sql(const dynamic::Update& _stmt) noexcept {
+  using namespace std::ranges::views;
+
+  const auto to_str = [](const auto& _set) -> std::string {
+    return wrap_in_quotes(_set.col.name) + " = " +
+           column_or_value_to_sql(_set.to);
+  };
+
+  std::stringstream stream;
+
+  stream << "UPDATE ";
+
+  if (_stmt.table.schema) {
+    stream << wrap_in_quotes(*_stmt.table.schema) << ".";
+  }
+  stream << wrap_in_quotes(_stmt.table.name);
+
+  stream << " SET ";
+
+  stream << internal::strings::join(
+      ", ", internal::collect::vector(_stmt.sets | transform(to_str)));
+
+  if (_stmt.where) {
+    stream << " WHERE " << condition_to_sql(*_stmt.where);
+  }
+
+  stream << ";";
+
+  return stream.str();
+}
+
 }  // namespace sqlgen::postgres
diff --git a/src/sqlgen/sqlite/to_sql.cpp b/src/sqlgen/sqlite/to_sql.cpp
index cc4eed6..aaae05d 100644
--- a/src/sqlgen/sqlite/to_sql.cpp
+++ b/src/sqlgen/sqlite/to_sql.cpp
@@ -32,6 +32,10 @@ std::string select_from_to_sql(const dynamic::SelectFrom& _stmt) noexcept;
 
 std::string type_to_sql(const dynamic::Type& _type) noexcept;
 
+std::string update_to_sql(const dynamic::Update& _stmt) noexcept;
+
+// ----------------------------------------------------------------------------
+
 std::string column_or_value_to_sql(
     const dynamic::ColumnOrValue& _col) noexcept {
   const auto handle_value = [](const auto& _v) -> std::string {
@@ -270,6 +274,9 @@ std::string to_sql_impl(const dynamic::Statement& _stmt) noexcept {
     } else if constexpr (std::is_same_v<S, dynamic::SelectFrom>) {
       return select_from_to_sql(_s);
 
+    } else if constexpr (std::is_same_v<S, dynamic::Update>) {
+      return update_to_sql(_s);
+
     } else {
       static_assert(rfl::always_false_v<S>, "Unsupported type.");
     }
@@ -304,4 +311,34 @@ std::string type_to_sql(const dynamic::Type& _type) noexcept {
   });
 }
 
+std::string update_to_sql(const dynamic::Update& _stmt) noexcept {
+  using namespace std::ranges::views;
+
+  const auto to_str = [](const auto& _set) -> std::string {
+    return "\"" + _set.col.name + "\" = " + column_or_value_to_sql(_set.to);
+  };
+
+  std::stringstream stream;
+
+  stream << "UPDATE ";
+
+  if (_stmt.table.schema) {
+    stream << "\"" << *_stmt.table.schema << "\".";
+  }
+  stream << "\"" << _stmt.table.name << "\"";
+
+  stream << " SET ";
+
+  stream << internal::strings::join(
+      ", ", internal::collect::vector(_stmt.sets | transform(to_str)));
+
+  if (_stmt.where) {
+    stream << " WHERE " << condition_to_sql(*_stmt.where);
+  }
+
+  stream << ";";
+
+  return stream.str();
+}
+
 }  // namespace sqlgen::sqlite
diff --git a/tests/postgres/test_update_dry.cpp b/tests/postgres/test_update_dry.cpp
new file mode 100644
index 0000000..1266282
--- /dev/null
+++ b/tests/postgres/test_update_dry.cpp
@@ -0,0 +1,27 @@
+#include <gtest/gtest.h>
+
+#include <sqlgen.hpp>
+#include <sqlgen/postgres.hpp>
+
+namespace test_update_dry {
+
+struct TestTable {
+  std::string field1;
+  int32_t field2;
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::optional<std::string> nullable;
+};
+
+TEST(postgres, test_update_dry) {
+  using namespace sqlgen;
+
+  const auto query =
+      update<TestTable>("field1"_c.set("Hello"), "nullable"_c.set("field1"_c)) |
+      where("field2"_c > 0);
+
+  const auto expected =
+      R"(UPDATE "TestTable" SET "field1" = 'Hello', "nullable" = "field1" WHERE "field2" > 0;)";
+
+  EXPECT_EQ(sqlgen::postgres::to_sql(query), expected);
+}
+}  // namespace test_update_dry
diff --git a/tests/sqlite/test_update.cpp b/tests/sqlite/test_update.cpp
new file mode 100644
index 0000000..b41e360
--- /dev/null
+++ b/tests/sqlite/test_update.cpp
@@ -0,0 +1,51 @@
+#include <gtest/gtest.h>
+
+#include <rfl.hpp>
+#include <rfl/json.hpp>
+#include <sqlgen.hpp>
+#include <sqlgen/sqlite.hpp>
+#include <vector>
+
+namespace test_update {
+
+struct Person {
+  sqlgen::PrimaryKey<uint32_t> id;
+  std::string first_name;
+  std::string last_name;
+  int age;
+};
+
+TEST(sqlite, test_update) {
+  const auto people1 = std::vector<Person>(
+      {Person{
+           .id = 0, .first_name = "Homer", .last_name = "Simpson", .age = 45},
+       Person{.id = 1, .first_name = "Bart", .last_name = "Simpson", .age = 10},
+       Person{.id = 2, .first_name = "Lisa", .last_name = "Simpson", .age = 8},
+       Person{
+           .id = 3, .first_name = "Maggie", .last_name = "Simpson", .age = 0},
+       Person{
+           .id = 4, .first_name = "Hugo", .last_name = "Simpson", .age = 10}});
+
+  const auto conn = sqlgen::sqlite::connect();
+
+  sqlgen::write(conn, people1);
+
+  using namespace sqlgen;
+
+  const auto query =
+      update<Person>("first_name"_c.set("last_name"_c), "age"_c.set(100)) |
+      where("first_name"_c == "Hugo");
+
+  query(conn).value();
+
+  const auto people2 = sqlgen::read<std::vector<Person>>(conn).value();
+
+  std::cout << rfl::json::write(people2) << std::endl;
+
+  const std::string expected =
+      R"([{"id":0,"first_name":"Homer","last_name":"Simpson","age":45},{"id":1,"first_name":"Bart","last_name":"Simpson","age":10},{"id":2,"first_name":"Lisa","last_name":"Simpson","age":8},{"id":3,"first_name":"Maggie","last_name":"Simpson","age":0},{"id":4,"first_name":"Simpson","last_name":"Simpson","age":100}])";
+
+  EXPECT_EQ(rfl::json::write(people2), expected);
+}
+
+}  // namespace test_update