added column_pointer support to fk

dev/constraints.h

@@ -16,6 +16,7 @@
 #include "error_code.h"
 #include "table_type_of.h"
 #include "type_printer.h"
+#include "column_pointer.h"
 
 namespace sqlite_orm {
 
@@ -375,6 +376,11 @@ namespace sqlite_orm {
             foreign_key_t<std::tuple<Cs...>, std::tuple<Rs...>> references(Rs... refs) {
                 return {std::move(this->columns), {std::forward<Rs>(refs)...}};
             }
+
+            template<class T, class... Rs>
+            foreign_key_t<std::tuple<Cs...>, std::tuple<internal::column_pointer<T, Rs>...>> references(Rs... refs) {
+                return {std::move(this->columns), {sqlite_orm::column<T>(refs)...}};
+            }
         };
 #endif
 

include/sqlite_orm/sqlite_orm.h

@@ -3191,6 +3191,8 @@ namespace sqlite_orm {
 
 // #include "type_printer.h"
 
+// #include "column_pointer.h"
+
 namespace sqlite_orm {
 
     namespace internal {
@@ -3549,6 +3551,11 @@ namespace sqlite_orm {
             foreign_key_t<std::tuple<Cs...>, std::tuple<Rs...>> references(Rs... refs) {
                 return {std::move(this->columns), {std::forward<Rs>(refs)...}};
             }
+
+            template<class T, class... Rs>
+            foreign_key_t<std::tuple<Cs...>, std::tuple<internal::column_pointer<T, Rs>...>> references(Rs... refs) {
+                return {std::move(this->columns), {sqlite_orm::column<T>(refs)...}};
+            }
         };
 #endif
 

tests/constraints/foreign_key.cpp

@@ -128,4 +128,84 @@ TEST_CASE("Foreign key 2") {
 
     storage.update(t2);
 }
+
+TEST_CASE("Foreign key with inheritance") {
+    struct Person {
+        int id;
+        std::string name;
+        int age;
+    };
+
+    // Define derived class Student
+    struct Student : public Person {
+        std::string school_name;
+
+        Student(int id, std::string name, int age, std::string school_name) :
+            Person{id, std::move(name), age}, school_name(std::move(school_name)) {}
+    };
+
+    // Define derived class Teacher
+    struct Teacher : public Person {
+        std::string subject;
+        double salary;
+
+        Teacher(int id, std::string name, int age, std::string subject, double salary) :
+            Person{id, std::move(name), age}, subject(subject), salary(salary) {}
+    };
+
+    // Define Classroom class referencing Teacher and Student
+    struct Classroom {
+        int id;
+        int teacher_id;  // Foreign key referencing Teacher
+        int student_id;  // Foreign key referencing Student
+        std::string room_name;
+    };
+
+    auto storage =
+        make_storage("",
+
+                     // Define the Person table as a base, though it is not used directly
+                     make_table<Person>("persons",
+                                        make_column("id", &Person::id, primary_key().autoincrement()),
+                                        make_column("name", &Person::name),
+                                        make_column("age", &Person::age)),
+
+                     // Define the Student table with foreign key inheritance
+                     make_table<Student>("students",
+                                         make_column("id", &Student::id, primary_key()),
+                                         make_column("name", &Student::name),
+                                         make_column("age", &Student::age),
+                                         make_column("school_name", &Student::school_name)),
+
+                     // Define the Teacher table with foreign key inheritance
+                     make_table<Teacher>("teachers",
+                                         make_column("id", &Teacher::id, primary_key()),
+                                         make_column("name", &Teacher::name),
+                                         make_column("age", &Teacher::age),
+                                         make_column("subject", &Teacher::subject),
+                                         make_column("salary", &Teacher::salary)),
+
+                     // Define the Classroom table with foreign keys to Teacher and Student
+                     make_table<Classroom>("classrooms",
+                                           make_column("id", &Classroom::id, primary_key().autoincrement()),
+                                           make_column("teacher_id", &Classroom::teacher_id),
+                                           make_column("student_id", &Classroom::student_id),
+                                           make_column("room_name", &Classroom::room_name),
+                                           foreign_key(&Classroom::teacher_id).references<Teacher>(&Teacher::id),
+                                           foreign_key(&Classroom::student_id).references<Student>(&Student::id)));
+    // Sync schema (create tables)
+    storage.sync_schema();
+
+    // Create and insert a Teacher record
+    Teacher teacher{0, "Mr. Smith", 45, "Mathematics", 55000.00};
+    int teacher_id = storage.insert(teacher);
+
+    // Create and insert a Student record
+    Student student = {0, "Alice", 20, "High School"};
+    int student_id = storage.insert(student);
+
+    // Create and insert a Classroom record with foreign keys
+    Classroom classroom = {0, teacher_id, student_id, "Room A"};
+    storage.insert(classroom);
+}
 #endif