extract not null constraint into enum

src/sql/column.cpp

@@ -16,14 +16,19 @@ column::column(std::string name, std::string alias)
   : name_(std::move(name)), attributes_(utils::null_attributes), alias_(std::move(alias))
 {}
 
-column::column(std::string name, data_type_t type, utils::field_attributes attr)
-  : name_(std::move(name)), type_(type), attributes_(attr)
+column::column(std::string name, data_type_t type, utils::field_attributes attr, null_option null_opt)
+  : name_(std::move(name)), type_(type), attributes_(attr), null_option_(null_opt)
 {}
 
 column::column(std::string name, data_type_t type, size_t index, std::string ref_table, std::string ref_column,
-               utils::field_attributes attr)
-  : name_(std::move(name)), index_(index), type_(type), attributes_(attr), ref_table_(std::move(ref_table)),
-    ref_column_(std::move(ref_column))
+               utils::field_attributes attr, null_option null_opt)
+  : name_(std::move(name))
+  , index_(index)
+  , type_(type)
+  , attributes_(attr)
+  , null_option_(null_opt)
+  , ref_table_(std::move(ref_table))
+  , ref_column_(std::move(ref_column))
 {}
 
 const std::string &column::name() const
@@ -41,6 +46,11 @@ const utils::field_attributes &column::attributes() const
   return attributes_;
 }
 
+bool column::is_nullable() const
+{
+  return null_option_ == null_option::NULLABLE;
+}
+
 data_type_t column::type() const
 {
   return type_;
@@ -93,18 +103,15 @@ column operator "" _col(const char *name, size_t len)
   return {std::string(name, len)};
 }
 
-column make_column(const std::string &name, data_type_t type, utils::field_attributes attr)
+column make_column(const std::string &name, data_type_t type, utils::field_attributes attr, null_option null_opt)
 {
-  return {name, type, attr};
+  return {name, type, attr, null_opt};
 }
 
 template<>
-column make_column<std::string>(const std::string &name, utils::field_attributes attr)
+column make_column<std::string>(const std::string &name, utils::field_attributes attr, null_option null_opt)
 {
-  if (attr.options() == utils::constraints::NONE) {
-    return make_column(name, data_type_traits<std::string>::builtin_type(attr.size()), { attr.size(), utils::constraints::NOT_NULL});
-  }
-  return make_column(name, data_type_traits<std::string>::builtin_type(attr.size()), attr);
+  return make_column(name, data_type_traits<std::string>::builtin_type(attr.size()), attr, null_opt);
 }
 
 template<>
@@ -117,6 +124,6 @@ template<>
 [[maybe_unused]] column make_fk_column<std::string>(const std::string &name, size_t size, const std::string &ref_table,
                                                     const std::string &ref_column)
 {
-  return {name, data_type_traits<std::string>::builtin_type(size), 0, ref_table, ref_column, {size, utils::constraints::PRIMARY_KEY | utils::constraints::NOT_NULL}};
+  return {name, data_type_traits<std::string>::builtin_type(size), 0, ref_table, ref_column, {size, utils::constraints::FOREIGN_KEY}, null_option::NOT_NULL};
 }
 }

src/sql/column_generator.cpp

@@ -10,7 +10,7 @@ column_generator::column_generator(std::vector<column> &columns, const table_rep
 
 void column_generator::on_primary_key(const char *id, std::string &pk, size_t size)
 {
-  on_attribute(id, pk, { size, utils::constraints::PRIMARY_KEY | utils::constraints::NOT_NULL });
+  on_attribute(id, pk, { size, utils::constraints::PRIMARY_KEY });
 }
 
 void column_generator::on_revision(const char *id, unsigned long long int &x)

src/sql/query_builder.cpp

@@ -473,7 +473,7 @@ std::string build_create_column(const column &col, const dialect &d, column_cont
   if (col.attributes().size() > 0) {
     result.append("(" + std::to_string(col.attributes().size()) + ")");
   }
-  if (is_constraint_set(col.attributes().options(), utils::constraints::NOT_NULL)) {
+  if (!col.is_nullable()) {
     result.append(" NOT NULL");
   }
   if (is_constraint_set(col.attributes().options(), utils::constraints::UNIQUE)) {