determine NOT NULL constraint from std::optional

include/matador/sql/column_generator.hpp

@@ -73,7 +73,10 @@ public:
   void on_revision(const char *id, unsigned long long &rev);
 
   template<typename Type>
-  void on_attribute(const char *id, Type &x, const utils::field_attributes &attr = utils::null_attributes);
+  void on_attribute(const char *id, Type &x, const utils::field_attributes &attr = utils::not_null_attributes);
+
+  template<typename Type>
+  void on_attribute(const char *id, std::optional<Type> &x, const utils::field_attributes &attr = utils::null_attributes);
 
   template<class Pointer>
   void on_belongs_to(const char *id, Pointer &x, utils::cascade_type)
@@ -106,13 +109,23 @@ private:
 template<typename V>
 void column_generator::on_primary_key(const char *id, V &x, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type*)
 {
-  on_attribute(id, x, { utils::constraints::PRIMARY_KEY });
+  on_attribute(id, x, { utils::constraints::PRIMARY_KEY | utils::constraints::NOT_NULL });
 }
 
 template<typename Type>
 void column_generator::on_attribute(const char *id, Type &x, const utils::field_attributes &attr)
 {
-  columns_.emplace_back(id, x, attr);
+  if (attr.options() == utils::constraints::NONE) {
+    columns_.push_back(column{id, x, { attr.size(), utils::constraints::NOT_NULL}});
+  } else {
+    columns_.emplace_back(id, x, attr);
+  }
+}
+
+template<typename Type>
+void column_generator::on_attribute(const char *id, std::optional<Type> &x, const utils::field_attributes &attr)
+{
+  columns_.emplace_back(id, data_type_traits<Type>::builtin_type(attr.size()), attr);
 }
 
 }

include/matador/utils/access.hpp

@@ -4,6 +4,7 @@
 #include "matador/utils/cascade_type.hpp"
 
 #include <string>
+#include <optional>
 
 namespace matador::utils {
 
@@ -44,6 +45,11 @@ void attribute(Operator &op, const char *id, Type &value, const field_attributes
   op.on_attribute(id, value, attr);
 }
 
+template<class Operator, class Type>
+void attribute(Operator &op, const char *id, std::optional<Type> &value, const field_attributes &attr) {
+  op.on_attribute(id, value, attr);
+}
+
 template<class Operator, class Type>
 void attribute(Operator &op, const char *id, Type &value) {
   op.on_attribute(id, value);