diff --git a/include/matador/object/object_ptr.hpp b/include/matador/object/object_ptr.hpp
index a4668c2..b7830c6 100644
--- a/include/matador/object/object_ptr.hpp
+++ b/include/matador/object/object_ptr.hpp
@@ -42,16 +42,16 @@ public:
   void reset() { proxy_.reset(); }
 
   operator bool() const { return valid(); }
-  [[nodiscard]] bool valid() const { return proxy_ != nullptr; }
+  [[nodiscard]] bool valid() const { return proxy_ != nullptr && !proxy_->empty(); }
 
   [[nodiscard]] bool has_primary_key() const { return proxy_->has_primary_key(); }
   [[nodiscard]] const utils::identifier &primary_key() const { return proxy_->primary_key(); }
   void primary_key(const utils::identifier &pk) { proxy_->primary_key(pk); }
 
   [[nodiscard]] bool is_persistent() const { return proxy_->is_persistent(); }
-  [[nodiscard]] bool is_transient() const { return !proxy_->is_transient(); }
-  [[nodiscard]] bool is_detached() const { return !proxy_->is_detached(); }
-  [[nodiscard]] bool is_removed() const { return !proxy_->is_removed(); }
+  [[nodiscard]] bool is_transient() const { return proxy_->is_transient(); }
+  [[nodiscard]] bool is_detached() const { return proxy_->is_detached(); }
+  [[nodiscard]] bool is_removed() const { return proxy_->is_removed(); }
 
   void change_state(object_state s) {
     if (proxy_) {
diff --git a/include/matador/orm/error_code.hpp b/include/matador/orm/error_code.hpp
index 7bfc679..215bc04 100644
--- a/include/matador/orm/error_code.hpp
+++ b/include/matador/orm/error_code.hpp
@@ -13,6 +13,7 @@ enum class error_code : uint8_t {
   NoPrimaryKey,
   FailedToBuildQuery,
   FailedToFindObject,
+  FailedToInsertObject,
   Failed
 };
 
diff --git a/include/matador/orm/session.hpp b/include/matador/orm/session.hpp
index eff0995..46222bf 100644
--- a/include/matador/orm/session.hpp
+++ b/include/matador/orm/session.hpp
@@ -14,6 +14,7 @@
 #include "matador/sql/connection.hpp"
 #include "matador/sql/connection_pool.hpp"
 #include "matador/sql/executor.hpp"
+#include "matador/sql/record.hpp"
 #include "matador/sql/resolver_service.hpp"
 #include "matador/sql/statement.hpp"
 #include "matador/sql/statement_cache.hpp"
@@ -105,40 +106,35 @@ utils::result<object::object_ptr<Type>, utils::error> session::insert(object::ob
   }
 
   // Build dependency-ordered insert steps (deps first, root last)
-  query::insert_query_builder iqb(schema_, contexts_by_type_);
+  query::insert_query_builder<Type> iqb(schema_, contexts_by_type_);
   auto steps = iqb.build(obj);
   if (!steps.is_ok()) {
     return utils::failure(make_error(error_code::FailedToBuildQuery, "Failed to build insert dependency queries."));
   }
 
   // Execute all steps; for Identity steps read RETURNING and write pk back into the object
-  for (auto &step : *steps) {
-    // if (step.pk_is_unset && step.set_pk) {
-    //   if (step.pk_generator == utils::generator_type::Manual) {
-    //     if (step.pk_is_unset()) {
-    //       return utils::failure(make_error(error_code::NoPrimaryKey, "Manual primary key is required but unset."));
-    //     }
-    //   } else if (step.pk_generator == utils::generator_type::Sequence) {
-    //     if (step.pk_is_unset()) {
-    //       // hard-coded naming as you specified earlier
-    //       // <table_name>_seq (table name known in schema meta; if you prefer, store it in step too)
-    //       // For now, we derive from the schema type used for the root insert: simplistic but works if table name == entity name.
-    //       const std::string seq_name = it->second.name() + "_seq";
-    //
-    //       auto id_res = query::select().nextval(seq_name).fetch_value<std::uint64_t>(*this);
-    //       if (!id_res.is_ok() || !id_res.value().has_value()) {
-    //         return utils::failure(make_error(error_code::FailedToBuildQuery, "Failed to obtain next sequence value."));
-    //       }
-    //       step.set_pk(*id_res.value());
-    //     }
-    //   } else if (step.pk_generator == utils::generator_type::Table) {
-    //     if (step.pk_is_unset()) {
-    //       // TODO: implement table id generation; same idea as above:
-    //       // UPDATE <table>_tbl_seq ... RETURNING ...
-    //       return utils::failure(make_error(error_code::Failed, "Table primary key generator not implemented yet."));
-    //     }
-    //   }
-    // }
+  for (query::insert_step &step : *steps) {
+    auto stmt = cache_.acquire(step.ctx);
+    if (!stmt.is_ok()) {
+      return utils::failure(stmt.err());
+    }
+    if (step.pk_generator == utils::generator_type::Identity) {
+      // insert and read RETURNING
+      auto record = stmt->fetch_one();
+      if (!record.is_ok()) {
+        return utils::failure(record.err());
+      }
+      if (!record.value().has_value()) {
+        return utils::failure(make_error(error_code::FailedToFindObject, "Failed to insert object and retrieve identity."));
+      }
+      step.apply_returning(*record.value());
+    } else if (step.pk_generator == utils::generator_type::Sequence || step.pk_generator == utils::generator_type::Table) {
+      auto result = it->second.pk_generator().next_id(*this);
+      if (!result.is_ok()) {
+        return utils::failure(result.err());
+      }
+      step.apply_primary_key(utils::identifier{*result});
+    }
 
     auto result = step.acquire_and_bind(cache_);
     if (!result.is_ok()) {
@@ -148,28 +144,6 @@ utils::result<object::object_ptr<Type>, utils::error> session::insert(object::ob
     if (const auto exec_result = result->execute(); !exec_result.is_ok()) {
       return utils::failure(exec_result.err());
     }
-
-    // --- Execute step ---
-    // if (std::holds_alternative<query::executable_query>(step.query)) {
-    //   const auto &q = std::get<query::executable_query>(step.query);
-    //   const auto exec_res = q.execute(*this);
-    //   if (!exec_res.is_ok()) {
-    //     return utils::failure(exec_res.err());
-    //   }
-    //   continue;
-    // }
-    //
-    // const auto &q = std::get<query::fetchable_query>(step.query);
-    // auto rec_res = q.fetch_one(*this);
-    // if (!rec_res.is_ok()) {
-    //   return utils::failure(rec_res.err());
-    // }
-    // if (!rec_res.value().has_value()) {
-    //   return utils::failure(make_error(error_code::FailedToFindObject, "INSERT ... RETURNING did not return a row."));
-    // }
-    // if (step.apply_returning) {
-    //   step.apply_returning(*rec_res.value());
-    // }
   }
 
   obj.change_state(object::object_state::Persistent);
diff --git a/include/matador/query/insert_query_builder.hpp b/include/matador/query/insert_query_builder.hpp
index 36e5770..274b00e 100644
--- a/include/matador/query/insert_query_builder.hpp
+++ b/include/matador/query/insert_query_builder.hpp
@@ -1,7 +1,7 @@
 #ifndef MATADOR_INSERT_QUERY_BUILDER_HPP
 #define MATADOR_INSERT_QUERY_BUILDER_HPP
 
-#include <utility>
+#include "matador/object/collection.hpp"
 
 #include "matador/query/basic_schema.hpp"
 #include "matador/query/intermediates/executable_query.hpp"
@@ -62,6 +62,7 @@ struct insert_step {
 
   // Identity post-insert
   std::function<void(const sql::record &)> apply_returning{};
+  std::function<void(const utils::identifier &)> apply_primary_key{};
   std::function<void(sql::statement &)> bind_object{};
 };
 
@@ -110,21 +111,24 @@ public:
     on_foreign_object(obj, attr);
   }
   template<class CollectionType>
-  void on_has_many(const char * /*id*/, CollectionType &objects, const char *join_column, const utils::foreign_attributes &attr, std::enable_if_t<object::is_object_ptr<typename CollectionType::value_type>::value> * = nullptr) {
+  void on_has_many(const char * /*id*/, object::collection<object::object_ptr<CollectionType>> &objects, const char *join_column, const utils::foreign_attributes &attr) {
     if (!utils::is_cascade_type_set(attr.cascade(), utils::cascade_type::Insert)) {
       return;
     }
 
-    has_many_linker<typename CollectionType::value_type> linker(ptr_, join_column);
+    has_many_linker<ObjectType> linker(ptr_, join_column);
     for (auto &obj : objects) {
-      obj.is_persistent() ? build_for(obj) : on_foreign_object(obj, attr);
+      if (obj.is_transient()) {
+        build_for(obj);
+      }
+      // obj.is_persistent() ? build_for(obj) : on_foreign_object(obj, attr);
 
-      access::process(linker, obj);
+      access::process(linker, *obj);
     }
 
   }
   template<class CollectionType>
-  void on_has_many(const char * /*id*/, CollectionType &/*con*/, const char *, const utils::foreign_attributes &/*attr*/, std::enable_if_t<!object::is_object_ptr<typename CollectionType::value_type>::value> * = nullptr) {}
+  static void on_has_many(const char * /*id*/, object::collection<CollectionType> &/*con*/, const char *, const utils::foreign_attributes &/*attr*/) {}
   template<class Collection>
   void on_has_many_to_many(const char *id, Collection &container, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes & ) {
     if (id == nullptr || join_column == nullptr || inverse_join_column == nullptr) {
@@ -230,8 +234,10 @@ private:
         id.assign(f.value());
         step.pk_accessor.set(*ptr, id);
       };
-    } else {
-      // step.query = executable_query{insert().into(it->second.table()).values(*ptr)};
+    } else if (info.has_primary_key() && step.pk_generator == utils::generator_type::Sequence || step.pk_generator == utils::generator_type::Table) {
+      step.apply_primary_key = [ptr, &step](const utils::identifier &id) {
+        step.pk_accessor.set(*ptr, id);
+      };
     }
     steps_.push_back(std::move(step));
   }
diff --git a/include/matador/utils/identifier.hpp b/include/matador/utils/identifier.hpp
index b7f04f9..8df2594 100644
--- a/include/matador/utils/identifier.hpp
+++ b/include/matador/utils/identifier.hpp
@@ -198,16 +198,16 @@ private:
 template <typename Target, typename Source>
 bool in_range(Source value) {
   if constexpr (std::is_signed_v<Source> == std::is_signed_v<Target>) {
-    return value >= static_cast<Target>(std::numeric_limits<Source>::min()) &&
-           value <= static_cast<Target>(std::numeric_limits<Source>::max());
+    return value >= static_cast<Target>((std::numeric_limits<Source>::min)()) &&
+           value <= static_cast<Target>((std::numeric_limits<Source>::max)());
   } else if constexpr (std::is_signed_v<Source> && !std::is_signed_v<Target>) {
     if (value < 0) {
       return false;
     }
     using UnsignedSource = std::make_unsigned_t<Source>;
-    return static_cast<UnsignedSource>(value) <= std::numeric_limits<Target>::max();
+    return static_cast<UnsignedSource>(value) <= (std::numeric_limits<Target>::max)();
   } else {
-    return value <= static_cast<std::make_unsigned_t<Target>>(std::numeric_limits<Target>::max());
+    return value <= static_cast<std::make_unsigned_t<Target>>((std::numeric_limits<Target>::max)());
   }
 }
 
diff --git a/source/orm/orm/error_code.cpp b/source/orm/orm/error_code.cpp
index 26a911b..b3e17ed 100644
--- a/source/orm/orm/error_code.cpp
+++ b/source/orm/orm/error_code.cpp
@@ -20,6 +20,8 @@ std::string orm_category_impl::message(const int ev) const {
       return "Failed to build query";
     case error_code::FailedToFindObject:
       return "Failed to find object";
+    case error_code::FailedToInsertObject:
+      return "Failed to insert object";
     case error_code::Failed:
       return "Failed";
     default:
diff --git a/test/orm/query/InsertQueryBuilderTest.cpp b/test/orm/query/InsertQueryBuilderTest.cpp
index fe14667..44aeafa 100644
--- a/test/orm/query/InsertQueryBuilderTest.cpp
+++ b/test/orm/query/InsertQueryBuilderTest.cpp
@@ -6,6 +6,8 @@
 #include "matador/sql/connection.hpp"
 #include "matador/sql/interface/connection_impl.hpp"
 
+#include "matador/query/query_contexts.hpp"
+#include "matador/query/query.hpp"
 #include "matador/query/schema.hpp"
 
 #include "matador/query/insert_query_builder.hpp"
@@ -22,6 +24,46 @@ using namespace matador::sql;
 using namespace matador::query;
 using namespace matador::utils;
 
+std::unordered_map<std::type_index, query_contexts> to_contexts_by_name(const schema& scm, const dialect& d) {
+  std::unordered_map<std::type_index, query_contexts> contexts_by_type;
+  for (const auto &[type, node] : scm) {
+    query_contexts queries;
+
+    // SELECT all
+    queries.select_all = select(node.table())
+      .from(node.name())
+      .compile(d);
+    if (node.table().has_primary_key()) {
+      // SELECT one
+      queries.select_one = select(node.table())
+        .from(node.name())
+        .where(*node.table().primary_key_column().value() == _)
+        .compile(d);
+      // UPDATE one
+      auto update_set = update(node.table());
+      for (const auto &col: node.table().columns()) {
+        update_set.set(col, _);
+      }
+      queries.update_one = update_set.where(*node.table().primary_key_column().value() == _)
+        .compile(d);
+      // DELETE one
+      queries.delete_one = remove()
+        .from(node.name())
+        .where(*node.table().primary_key_column().value() == _)
+        .compile(d);
+    }
+    // INSERT one
+    queries.insert = insert()
+      .into(node.name(), node.table())
+      .values(generator::placeholders(node.table().columns().size()))
+      .compile(d);
+
+    contexts_by_type[node.node().type_index()] = queries;
+  }
+  
+  return contexts_by_type;
+}
+
 TEST_CASE("insert query builder test", "[query][insert_query_builder]") {
   using namespace matador::test;
   backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
@@ -32,7 +74,8 @@ TEST_CASE("insert query builder test", "[query][insert_query_builder]") {
     .and_then( [&scm] { return scm.attach<flight>("flights"); } );
   REQUIRE(result);
 
-  insert_query_builder iqb(scm);
+  const auto contexts_by_type = to_contexts_by_name(scm, db.dialect());
+  insert_query_builder<airplane> iqb(scm, contexts_by_type);
 
   const auto a380 = make_object<airplane>(1, "Boeing", "A380"  );
   auto build_result = iqb.build(a380);
@@ -40,12 +83,6 @@ TEST_CASE("insert query builder test", "[query][insert_query_builder]") {
 
   const auto& stmts = *build_result;
   REQUIRE(stmts.size() == 1);
-
-  const auto step = stmts.front();
-
-  REQUIRE(std::holds_alternative<executable_query>(step.query));
-  const auto sql = std::get<executable_query>(step.query).str(db);
-  REQUIRE(sql == R"(INSERT INTO "airplanes" ("id", "brand", "model") VALUES (1, 'Boeing', 'A380'))");
 }
 
 TEST_CASE("Test insert builder has many", "[query][insert_query_builder][has_many]") {
@@ -58,19 +95,21 @@ TEST_CASE("Test insert builder has many", "[query][insert_query_builder][has_man
     .and_then( [&scm] { return scm.attach<author>("authors"); } );
   REQUIRE(result.is_ok());
 
-  // auto s_king = make_object<author>(1, "Steven", "King", "21.9.1947", 1956, false);
-  //
-  // s_king->books.push_back(make_object<book>(2, "Carrie", object_ptr<author>{}, 1974));
-  // s_king->books.push_back(make_object<book>(3, "The Shining", object_ptr<author>{}, 1977));
-  // s_king->books.push_back(make_object<book>(4, "It", object_ptr<author>{}, 1986));
-  // s_king->books.push_back(make_object<book>(5, "Misery", object_ptr<author>{}, 1987));
-  // s_king->books.push_back(make_object<book>(6, "The Dark Tower: The Gunslinger", object_ptr<author>{}, 1982));
-  //
-  // insert_query_builder iqb(scm);
-  //
-  // auto build_result = iqb.build(s_king);
-  // REQUIRE(build_result.is_ok());
-  //
-  // const auto& stmts = *build_result;
-  // REQUIRE(stmts.size() == 1);
+  auto s_king = make_object<author>(1, "Steven", "King", "21.9.1947", 1956, false);
+
+  s_king->books.push_back(make_object<book>(2, "Carrie", object_ptr<author>{}, 1974));
+  s_king->books.push_back(make_object<book>(3, "The Shining", object_ptr<author>{}, 1977));
+  s_king->books.push_back(make_object<book>(4, "It", object_ptr<author>{}, 1986));
+  s_king->books.push_back(make_object<book>(5, "Misery", object_ptr<author>{}, 1987));
+  s_king->books.push_back(make_object<book>(6, "The Dark Tower: The Gunslinger", object_ptr<author>{}, 1982));
+
+  const auto contexts_by_type = to_contexts_by_name(scm, db.dialect());
+  insert_query_builder<author> iqb(scm, contexts_by_type);
+
+  auto build_result = iqb.build(s_king);
+  REQUIRE(build_result.is_ok());
+
+  const auto& stmts = *build_result;
+  REQUIRE_FALSE(stmts.empty());
+  REQUIRE(stmts.size() == 6);
 }
\ No newline at end of file