serialize a model to flat string even when a DO_NOTHING_ON_SAVE flag is set

while here:
- add FT::serialize_to_null_if_null and FT::do_not_serialize_if_null flags

src/baseexpression.cpp

@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018-2022, Tomasz Sowa
+ * Copyright (c) 2018-2023, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -112,22 +112,36 @@ bool BaseExpression::get_allow_to_use_prefix()
 
 
 void BaseExpression::generate_from_model(pt::TextStream & stream, Model & model)
+{
+	FT field_type = FT::default_type;
+	generate_from_model(stream, model, field_type);
+}
+
+
+void BaseExpression::generate_from_model(pt::TextStream & stream, Model & model, const FT & field_type)
 {
 	this->out_stream = &stream;
-	generate_from_model(model);
+	generate_from_model(model, field_type);
 	this->out_stream = nullptr;
 }
 
 
-void BaseExpression::generate_from_model(Model & model)
+void BaseExpression::generate_from_model(Model & model, const FT & field_type)
 {
 	if( out_stream )
 	{
-		before_generate_from_model();
+		if( should_field_model_be_generated_as_null(model.get_has_primary_key_set(), field_type) )
-		dump_additional_info(model);
+		{
-		model.fields();
+			put_null_value();
-		add_additional_columns(model);
+		}
-		after_generate_from_model();
+		else
+		{
+			before_generate_from_model();
+			dump_additional_info(model);
+			model.fields();
+			add_additional_columns(model);
+			after_generate_from_model();
+		}
 	}
 }
 
@@ -164,6 +178,17 @@ bool BaseExpression::can_field_be_generated(const FT &)
 }
 
 
+bool BaseExpression::can_field_model_be_generated(bool has_model_primary_key, const FT & field_type)
+{
+	return true;
+}
+
+
+bool BaseExpression::should_field_model_be_generated_as_null(bool has_model_primary_key, const FT & field_type)
+{
+	return false;
+}
+
 void BaseExpression::field_before()
 {
 	if( !is_first_field )

src/baseexpression.h

@@ -75,6 +75,7 @@ public:
 	virtual void clear();
 
 	virtual void generate_from_model(pt::TextStream & stream, Model & model);
+	virtual void generate_from_model(pt::TextStream & stream, Model & model, const FT & field_type);
 
 	virtual pt::TextStream * get_current_stream();
 
@@ -232,7 +233,7 @@ public:
 			{
 				put_field_name_and_table_if_needed(field_name, field_type, model_env);
 				put_name_value_separator();
-				put_field_value_list(field_value, model_container_type, model_connector, model_env, foo);
+				put_field_value_list(field_value, model_container_type, field_type, model_connector, model_env, foo);
 			}
 			else
 			if( work_mode == MORM_WORK_MODE_MODEL_FIELDS_VALUES_FIELDS )
@@ -240,7 +241,7 @@ public:
 				(*out_stream) << '\n';
 				put_field_name_and_table_if_needed(field_name, field_type, model_env);
 				put_name_value_separator();
-				put_field_value_list(field_value, model_container_type, model_connector, model_env, foo);
+				put_field_value_list(field_value, model_container_type, field_type, model_connector, model_env, foo);
 				put_name_value_separator();
 				/*
 				 * IMPROVEME currently only used in XML serializer so we put / directly here
@@ -267,7 +268,7 @@ public:
 	template<typename ModelClass>
 	void field_model(const wchar_t * field_name, ModelClass & field_model, const FT & field_type, ModelEnv * model_env)
 	{
-		if( out_stream && can_field_be_generated(field_type) )
+		if( out_stream && can_field_be_generated(field_type) && can_field_model_be_generated(field_model.get_has_primary_key_set(), field_type) )
 		{
 			field_before();
 
@@ -278,14 +279,14 @@ public:
 			else
 			if( work_mode == MORM_WORK_MODE_MODEL_VALUES )
 			{
-				generate_from_model(field_model); // is it ok as a value?
+				generate_from_model(field_model, field_type); // is it ok as a value?
 			}
 			else
 			if( work_mode == MORM_WORK_MODE_MODEL_FIELDS_VALUES )
 			{
 				put_field_name_and_table_if_needed(field_name, field_type, model_env);
 				put_name_value_separator();
-				generate_from_model(field_model);
+				generate_from_model(field_model, field_type);
 			}
 			else
 			if( work_mode == MORM_WORK_MODE_MODEL_FIELDS_VALUES_FIELDS )
@@ -293,7 +294,7 @@ public:
 				(*out_stream) << '\n';
 				put_field_name_and_table_if_needed(field_name, field_type, model_env);
 				put_name_value_separator();
-				generate_from_model(field_model);
+				generate_from_model(field_model, field_type);
 				put_name_value_separator();
 				/*
 				 * IMPROVEME currently only used in XML serializer so we put / directly here
@@ -450,11 +451,15 @@ protected:
 	pt::TextStream scratch_buffer_local;
 	pt::TextStream * scratch_buffer;
 
-	virtual void generate_from_model(Model & model);
+	virtual void generate_from_model(Model & model, const FT & field_type);
 
 	virtual void before_generate_from_model();
 	virtual void after_generate_from_model();
+
 	virtual bool can_field_be_generated(const FT &);
+	virtual bool can_field_model_be_generated(bool has_model_primary_key, const FT & field_type);
+	virtual bool should_field_model_be_generated_as_null(bool has_model_primary_key, const FT & field_type);
+
 	virtual void field_before();
 	virtual void field_after();
 
@@ -527,18 +532,18 @@ protected:
 
 
 	template<typename ModelContainer, typename ModelContainerType, typename IsContainerByValueRenameMe>
-	void put_field_value_list(ModelContainer & field_value, ModelContainerType * model_container_type, ModelConnector * model_connector,
+	void put_field_value_list(ModelContainer & field_value, ModelContainerType * model_container_type, const FT & field_type,
-							  ModelEnv * model_env, IsContainerByValueRenameMe * foo)
+			ModelConnector * model_connector, ModelEnv * model_env, IsContainerByValueRenameMe * foo)
 	{
 		if constexpr (std::is_base_of<Model, ModelContainerType>())
 		{
 			if constexpr (std::is_base_of<Model, IsContainerByValueRenameMe>())
 			{
-				put_field_value_list_model_by_value(field_value, model_container_type, model_connector, model_env);
+				put_field_value_list_model_by_value(field_value, model_container_type, field_type, model_connector, model_env);
 			}
 			else
 			{
-				put_field_value_list_model_by_pointer(field_value, model_container_type, model_connector, model_env);
+				put_field_value_list_model_by_pointer(field_value, model_container_type, field_type, model_connector, model_env);
 			}
 		}
 		else
@@ -549,8 +554,8 @@ protected:
 
 
 	template<typename ModelContainer, typename ModelContainerType>
-	void put_field_value_list_model_by_value(ModelContainer & field_value, ModelContainerType * model_container_type, ModelConnector * model_connector,
+	void put_field_value_list_model_by_value(ModelContainer & field_value, ModelContainerType * model_container_type, const FT & field_type,
-									ModelEnv * model_env)
+			ModelConnector * model_connector, ModelEnv * model_env)
 	{
 		if( model_connector && model_env && out_stream )
 		{
@@ -559,13 +564,16 @@ protected:
 
 			for(auto & child_model_item : field_value)
 			{
-				if( !is_first )
+				if( can_field_model_be_generated(child_model_item.get_has_primary_key_set(), field_type) )
 				{
-					field_value_list_separator();
+					if( !is_first )
-				}
+					{
+						field_value_list_separator();
+					}
 
-				put_field_value_list_model(child_model_item, model_connector, model_env);
+					put_field_value_list_model(child_model_item, model_connector, model_env);
-				is_first = false;
+					is_first = false;
+				}
 			}
 
 			after_field_value_list();
@@ -574,8 +582,8 @@ protected:
 
 
 	template<typename ModelContainer, typename ModelContainerType>
-	void put_field_value_list_model_by_pointer(ModelContainer & field_value, ModelContainerType * model_container_type, ModelConnector * model_connector,
+	void put_field_value_list_model_by_pointer(ModelContainer & field_value, ModelContainerType * model_container_type, const FT & field_type,
-									ModelEnv * model_env)
+			ModelConnector * model_connector, ModelEnv * model_env)
 	{
 		if( model_connector && model_env && out_stream )
 		{
@@ -584,13 +592,16 @@ protected:
 
 			for(auto * child_model_item : field_value)
 			{
-				if( !is_first )
+				if( can_field_model_be_generated(child_model_item->get_has_primary_key_set(), field_type) )
 				{
-					field_value_list_separator();
+					if( !is_first )
-				}
+					{
+						field_value_list_separator();
+					}
 
-				put_field_value_list_model(*child_model_item, model_connector, model_env);
+					put_field_value_list_model(*child_model_item, model_connector, model_env);
-				is_first = false;
+					is_first = false;
+				}
 			}
 
 			after_field_value_list();
@@ -607,7 +618,8 @@ protected:
 		child_model.model_env->model = &child_model;
 		child_model.set_connector(model_connector);
 
-		generate_from_model(child_model);
+		FT field_type = FT::default_type;
+		generate_from_model(child_model, field_type);
 
 		child_model.model_env = nullptr;
 	}

src/flatexpression.cpp

@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018-2022, Tomasz Sowa
+ * Copyright (c) 2018-2023, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -39,6 +39,18 @@
 namespace morm
 {
 
+bool FlatExpression::should_field_model_be_generated_as_null(bool has_model_primary_key, const FT & field_type)
+{
+	return !has_model_primary_key && field_type.is_serialize_to_null_if_null();
+}
+
+
+
+bool FlatExpression::can_field_model_be_generated(bool has_model_primary_key, const FT & field_type)
+{
+	return has_model_primary_key || !field_type.is_do_not_serialize_if_null();
+}
+
 
 
 }

src/flatexpression.h

@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018-2022, Tomasz Sowa
+ * Copyright (c) 2018-2023, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -46,6 +46,10 @@ class FlatExpression : public BaseExpression
 public:
 
 
+protected:
+
+	bool should_field_model_be_generated_as_null(bool has_model_primary_key, const FT & field_type);
+	bool can_field_model_be_generated(bool has_model_primary_key, const FT & field_type);
 
 
 };

src/ft.h

@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2021-2022, Tomasz Sowa
+ * Copyright (c) 2021-2023, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -68,6 +68,15 @@ public:
 		date_only = 32768, /* use only year, month and day from pt::Date, no_time_zone flag is not used here */
 		time_only = 65536, /* use only hour, min, sec from pt::Date, no_time_zone flag is not used here */
 		no_time_zone = 131072, /* no time zone, used only with pt::Date */
+
+		/*
+		 * if this flag is set and a model does not have a primary key set
+		 * then we print only 'null'
+		 * (this is used only with flat strings)
+		 *
+		 */
+		serialize_to_null_if_null = 262144,
+		do_not_serialize_if_null = 524288, /* null objects are completely skipped when serializing to a flat string (test only for Model objects, not lists/vectors with childs models */
 	};
 
 	/*
@@ -212,6 +221,16 @@ public:
 		return is_flag_set(no_time_zone);
 	}
 
+	bool is_serialize_to_null_if_null() const
+	{
+		return is_flag_set(serialize_to_null_if_null);
+	}
+
+	bool is_do_not_serialize_if_null() const
+	{
+		return is_flag_set(do_not_serialize_if_null);
+	}
+
 };
 
 }

src/model.cpp

@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018-2022, Tomasz Sowa
+ * Copyright (c) 2018-2023, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -95,7 +95,7 @@ void Model::set_has_primary_key_set(bool has_primary_key)
 }
 
 
-bool Model::get_has_primary_key_set()
+bool Model::get_has_primary_key_set() const
 {
 	return this->has_primary_key_set;
 }
@@ -1448,7 +1448,7 @@ void Model::field_model_generate_flat_string(const wchar_t * flat_field_name, Mo
 
 		if( flat_expression )
 		{
-			if( model_env->dump_mode || field_model.save_mode == DO_INSERT_ON_SAVE || field_model.save_mode == DO_UPDATE_ON_SAVE )
+			if( model_env->dump_mode || field_model.save_mode != DO_DELETE_ON_SAVE )
 			{
 				field_model.model_env->model_work_mode = MORM_MODEL_WORK_MODE_GENERATING_FLAT_STRING;
 				flat_expression->field_model(flat_field_name, field_model, field_type, model_env);

src/model.h

@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (c) 2018-2022, Tomasz Sowa
+ * Copyright (c) 2018-2023, Tomasz Sowa
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -157,7 +157,7 @@ public:
 	virtual void     set_save_mode2(SaveMode save_mode, bool update_whole_tree = true);
 
 	virtual void set_has_primary_key_set(bool has_primary_key);
-	virtual bool get_has_primary_key_set();
+	virtual bool get_has_primary_key_set() const;
 
 	virtual void mark_to_delete();
 	virtual void mark_to_remove();