Add NOT NULL column without default value initially as NULL

5 files changed, 82 insertions, 37 deletions

diff --git a/odb/relational/mssql/schema.cxx b/odb/relational/mssql/schema.cxx
index 2db0c12..d1d892a 100644
--- a/odb/relational/mssql/schema.cxx
+++ b/odb/relational/mssql/schema.cxx
@@ -341,23 +341,21 @@ namespace relational
         alter_column (base const& x): base (x) {}
 
         virtual void
-        traverse (sema_rel::alter_column& ac)
+        traverse (sema_rel::column& c)
         {
-          assert (ac.null_altered ());
-
           // Relax (NULL) in pre and tighten (NOT NULL) in post.
           //
-          if (pre_ != ac.null ())
+          if (pre_ != c.null ())
             return;
 
-          using sema_rel::alter_table;
-          alter_table& at (static_cast<alter_table&> (ac.scope ()));
+          using sema_rel::table;
+          table& at (static_cast<table&> (c.scope ()));
 
           pre_statement ();
 
           os << "ALTER TABLE " << quote_id (at.name ()) << endl
              << "  ALTER COLUMN ";
-          alter (ac);
+          alter (c);
           os << endl;
 
           post_statement ();
@@ -380,8 +378,11 @@ namespace relational
             alter_header (at.name ());
             os << "  ADD ";
 
-            instance<create_column> c (emitter (), stream (), format_);
-            trav_rel::unames n (*c);
+            instance<create_column> cc (emitter (), stream (), format_);
+            trav_rel::alter_column ac; // Override.
+            trav_rel::unames n;
+            n >> cc;
+            n >> ac;
             names (at, n);
             os << endl;
 
@@ -415,8 +416,8 @@ namespace relational
             alter_header (at.name ());
             os << "  DROP COLUMN ";
 
-            instance<drop_column> c (emitter (), stream (), format_);
-            trav_rel::unames n (*c);
+            instance<drop_column> dc (emitter (), stream (), format_);
+            trav_rel::unames n (*dc);
             names (at, n);
             os << endl;
 
diff --git a/odb/relational/oracle/schema.cxx b/odb/relational/oracle/schema.cxx
index 024701c..9dc1921 100644
--- a/odb/relational/oracle/schema.cxx
+++ b/odb/relational/oracle/schema.cxx
@@ -349,13 +349,11 @@ namespace relational
         alter_column (base const& x): base (x) {}
 
         virtual void
-        traverse (sema_rel::alter_column& ac)
+        traverse (sema_rel::column& c)
         {
-          assert (ac.null_altered ());
-
           // Relax (NULL) in pre and tighten (NOT NULL) in post.
           //
-          if (pre_ != ac.null ())
+          if (pre_ != c.null ())
             return;
 
           if (first_)
@@ -364,7 +362,7 @@ namespace relational
             os << "," << endl
                << "          ";
 
-          os << quote_id (ac.name ()) << (ac.null () ? " NULL" : " NOT NULL");
+          os << quote_id (c.name ()) << (c.null () ? " NULL" : " NOT NULL");
         }
       };
       entry<alter_column> alter_column_;
@@ -386,7 +384,10 @@ namespace relational
             os << "  ADD (";
 
             instance<create_column> cc (emitter (), stream (), format_);
-            trav_rel::unames n (*cc);
+            trav_rel::alter_column ac; // Override.
+            trav_rel::unames n;
+            n >> cc;
+            n >> ac;
             names (at, n);
             os << ")" << endl;
 
diff --git a/odb/relational/pgsql/schema.cxx b/odb/relational/pgsql/schema.cxx
index 7e0b7a5..575f8e4 100644
--- a/odb/relational/pgsql/schema.cxx
+++ b/odb/relational/pgsql/schema.cxx
@@ -215,10 +215,10 @@ namespace relational
         alter_column (base const& x): base (x) {}
 
         virtual void
-        alter (sema_rel::alter_column& ac)
+        alter (sema_rel::column& c)
         {
-          os << quote_id (ac.name ()) << " " <<
-            (ac.null () ? "DROP" : "SET") << " NOT NULL";
+          os << quote_id (c.name ()) << " " <<
+            (c.null () ? "DROP" : "SET") << " NOT NULL";
         }
       };
       entry<alter_column> alter_column_;
diff --git a/odb/relational/schema.hxx b/odb/relational/schema.hxx
index fcb176f..32cac41 100644
--- a/odb/relational/schema.hxx
+++ b/odb/relational/schema.hxx
@@ -312,11 +312,13 @@ namespace relational
       create_column (emitter_type& e,
                      ostream& os,
                      schema_format f,
+                     bool override_null = true,
                      bool* first = 0)
           : common (e, os),
             format_ (f),
             first_ (first != 0 ? *first : first_data_),
-            first_data_ (true)
+            first_data_ (true),
+            override_null_ (override_null)
       {
       }
 
@@ -326,7 +328,8 @@ namespace relational
             common (c),
             format_ (c.format_),
             first_ (&c.first_ != &c.first_data_ ? c.first_ : first_data_),
-            first_data_ (c.first_data_)
+            first_data_ (c.first_data_),
+            override_null_ (c.override_null_)
       {
       }
 
@@ -410,10 +413,20 @@ namespace relational
       virtual void
       null (sema_rel::column& c)
       {
+        bool n (c.null ());
+
+        // If we are adding a new column that doesn't allow NULL nor has
+        // a default value, add it as NULL. Later, after migration, we
+        // will convert it to NOT NULL.
+        //
+        if (override_null_ && c.is_a<sema_rel::add_column> () &&
+            !n && c.default_ ().empty ())
+          n = true;
+
         // Specify both cases explicitly for better readability,
         // especially in ALTER COLUMN clauses.
         //
-        os << (c.null () ? " NULL" : " NOT NULL");
+        os << (n ? " NULL" : " NOT NULL");
       }
 
       virtual void
@@ -431,6 +444,8 @@ namespace relational
       schema_format format_;
       bool& first_;
       bool first_data_;
+      bool add_;
+      bool override_null_; // Override NOT NULL in add_column.
     };
 
     struct create_primary_key: trav_rel::primary_key, virtual context
@@ -811,7 +826,9 @@ namespace relational
     // Migration.
     //
 
-    struct alter_column: trav_rel::alter_column, common
+    struct alter_column: trav_rel::alter_column,
+                         trav_rel::add_column,
+                         common
     {
       typedef alter_column base;
 
@@ -825,7 +842,8 @@ namespace relational
             pre_ (pre),
             first_ (first != 0 ? *first : first_data_),
             first_data_ (true),
-            def_ (e, os, f)
+            fl_ (false),
+            def_ (e, os, f, fl_)
       {
       }
 
@@ -837,7 +855,8 @@ namespace relational
             pre_ (c.pre_),
             first_ (&c.first_ != &c.first_data_ ? c.first_ : first_data_),
             first_data_ (c.first_data_),
-            def_ (common::e_, common::os_, c.format_)
+            fl_ (false),
+            def_ (common::e_, common::os_, c.format_, fl_)
       {
       }
 
@@ -848,21 +867,19 @@ namespace relational
       }
 
       virtual void
-      alter (sema_rel::alter_column& ac)
+      alter (sema_rel::column& c)
       {
         // By default use the whole definition.
         //
-        def_->create (ac);
+        def_->create (c);
       }
 
       virtual void
-      traverse (sema_rel::alter_column& ac)
+      traverse (sema_rel::column& c)
       {
-        assert (ac.null_altered ());
-
         // Relax (NULL) in pre and tighten (NOT NULL) in post.
         //
-        if (pre_ != ac.null ())
+        if (pre_ != c.null ())
           return;
 
         if (first_)
@@ -872,7 +889,24 @@ namespace relational
 
         os << "  ";
         alter_header ();
-        alter (ac);
+        alter (c);
+      }
+
+      virtual void
+      traverse (sema_rel::alter_column& ac)
+      {
+        assert (ac.null_altered ());
+        traverse (static_cast<sema_rel::column&> (ac));
+      }
+
+      virtual void
+      traverse (sema_rel::add_column& ac)
+      {
+        // We initially add NOT NULL columns without default values as
+        // NULL. Now, after the migration, we convert them to NOT NULL.
+        //
+        if (!ac.null () && ac.default_ ().empty ())
+          traverse (static_cast<sema_rel::column&> (ac));
       }
 
     protected:
@@ -880,6 +914,7 @@ namespace relational
       bool pre_;
       bool& first_;
       bool first_data_;
+      bool fl_; // (Im)perfect forwarding.
       instance<create_column> def_;
     };
 
@@ -971,7 +1006,7 @@ namespace relational
         bool f (true);  // Shared first flag.
         bool* pf (&f);  // (Im)perfect forwarding.
         bool tl (true); // (Im)perfect forwarding.
-        instance<create_column> cc (emitter (), stream (), format_, pf);
+        instance<create_column> cc (emitter (), stream (), format_, tl, pf);
         instance<alter_column> ac (emitter (), stream (), format_, tl, pf);
         trav_rel::unames n;
         n >> cc;
diff --git a/odb/relational/sqlite/schema.cxx b/odb/relational/sqlite/schema.cxx
index 6d3cba4..9d3f859 100644
--- a/odb/relational/sqlite/schema.cxx
+++ b/odb/relational/sqlite/schema.cxx
@@ -21,7 +21,13 @@ namespace relational
 
       struct create_column: relational::create_column, context
       {
-        create_column (base const& x): base (x) {}
+        create_column (base const& x): base (x)
+        {
+          // In SQLite it is impossible to alter a column later, so we add
+          // it as is.
+          //
+          override_null_ = false;
+        }
 
         virtual void
         traverse (sema_rel::add_column& ac)
@@ -118,9 +124,11 @@ namespace relational
         {
           // SQLite can only add a single column per ALTER TABLE statement.
           //
-          instance<create_column> c (emitter (), stream (), format_);
+          instance<create_column> cc (emitter (), stream (), format_);
+          trav_rel::alter_column ac; // Override.
           trav_rel::unames n;
-          n >> c;
+          n >> cc;
+          n >> ac;
           names (at, n);
 
           // SQLite does not support altering columns.