Implement on_delete pragma for object pointers

Translates to the ON DELETE SQL clause.

4 files changed, 83 insertions, 2 deletions

diff --git a/odb/relational/mssql/schema.cxx b/odb/relational/mssql/schema.cxx
index 2480e75..7b6c7ca 100644
--- a/odb/relational/mssql/schema.cxx
+++ b/odb/relational/mssql/schema.cxx
@@ -237,6 +237,20 @@ namespace relational
       {
         create_foreign_key (base const& x): base (x) {}
 
+        void
+        diagnose (sema_rel::foreign_key& fk)
+        {
+          if (fk.on_delete () != sema_rel::foreign_key::no_action)
+          {
+            cerr << "warning: foreign key '" << fk.name () << "' has " <<
+              "ON DELETE clause but is disabled in SQL Server due to lack "
+              "of deferrable constraint support" << endl;
+
+            cerr << "info: consider using non-deferrable foreign keys (" <<
+              "--fkeys-deferrable-mode)" << endl;
+          }
+        }
+
         virtual void
         traverse_create (sema_rel::foreign_key& fk)
         {
@@ -248,6 +262,8 @@ namespace relational
             base::traverse_create (fk);
           else
           {
+            diagnose (fk);
+
             // Don't bloat C++ code with comment strings if we are
             // generating embedded schema.
             //
@@ -268,6 +284,9 @@ namespace relational
         {
           bool c (!fk.not_deferrable () && !in_comment);
 
+          if (c)
+            diagnose (fk);
+
           if (c && format_ != schema_format::sql)
             return;
 
diff --git a/odb/relational/mysql/schema.cxx b/odb/relational/mysql/schema.cxx
index f06914a..473e746 100644
--- a/odb/relational/mysql/schema.cxx
+++ b/odb/relational/mysql/schema.cxx
@@ -145,6 +145,20 @@ namespace relational
       {
         create_foreign_key (base const& x): base (x) {}
 
+        void
+        diagnose (sema_rel::foreign_key& fk)
+        {
+          if (fk.on_delete () != sema_rel::foreign_key::no_action)
+          {
+            cerr << "warning: foreign key '" << fk.name () << "' has " <<
+              "ON DELETE clause but is disabled in MySQL due to lack "
+              "of deferrable constraint support" << endl;
+
+            cerr << "info: consider using non-deferrable foreign keys (" <<
+              "--fkeys-deferrable-mode)" << endl;
+          }
+        }
+
         virtual void
         traverse_create (sema_rel::foreign_key& fk)
         {
@@ -156,6 +170,8 @@ namespace relational
             base::traverse_create (fk);
           else
           {
+            diagnose (fk);
+
             // Don't bloat C++ code with comment strings if we are
             // generating embedded schema.
             //
@@ -178,6 +194,8 @@ namespace relational
             base::traverse_add (fk);
           else
           {
+            diagnose (fk);
+
             if (format_ != schema_format::sql)
               return;
 
diff --git a/odb/relational/schema.hxx b/odb/relational/schema.hxx
index 0de7036..4903e3a 100644
--- a/odb/relational/schema.hxx
+++ b/odb/relational/schema.hxx
@@ -857,14 +857,20 @@ namespace relational
 
         switch (a)
         {
+        case foreign_key::no_action:
+          break;
         case foreign_key::cascade:
           {
             os << endl
                << "    ON DELETE CASCADE";
             break;
           }
-        case foreign_key::no_action:
-          break;
+        case foreign_key::set_null:
+          {
+            os << endl
+               << "    ON DELETE SET NULL";
+            break;
+          }
         }
       }
 
diff --git a/odb/relational/validator.cxx b/odb/relational/validator.cxx
index c620a58..3218b57 100644
--- a/odb/relational/validator.cxx
+++ b/odb/relational/validator.cxx
@@ -51,6 +51,44 @@ namespace relational
             }
           }
         }
+
+        // Check on-delete.
+        //
+        if (m.count ("on-delete"))
+        {
+          const char* kp (container (m) ? "value" : "");
+          location l (m.location ());
+
+          // Make sure it is a pointer.
+          //
+          if (!object_pointer (member_utype (m, kp)))
+          {
+            error (l) << "on_delete specified for non-object pointer" << endl;
+            valid_ = false;
+          }
+
+          // Make sure it is not inverse.
+          //
+          if (inverse (m, kp))
+          {
+            error (l) << "on_delete specified for inverse object " <<
+              "pointer" << endl;
+            valid_ = false;
+          }
+
+          // Make sure the pointer is nullable if asked to set it to NULL.
+          //
+          using sema_rel::foreign_key;
+
+          if (m.get<foreign_key::action_type> ("on-delete") ==
+              foreign_key::set_null &&
+              !null (m, kp))
+          {
+            error (l) << "set_null specified for non-nullable object "
+              "pointer" << endl;
+            valid_ = false;
+          }
+        }
       }
 
       bool& valid_;