From 5125cad0209640b61007b921637c78504a4924d2 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 26 Apr 2013 13:16:57 +0200
Subject: Add --sqlite-override-null option

---
 odb/options.cli                 |  9 +++++++++
 odb/relational/model.hxx        | 14 +++++++++-----
 odb/relational/sqlite/model.cxx |  6 ++++++
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/odb/options.cli b/odb/options.cli
index c3bb908..63bbbb8 100644
--- a/odb/options.cli
+++ b/odb/options.cli
@@ -961,6 +961,15 @@ class options
   // SQLite-specific options.
   //
 
+  bool --sqlite-override-null
+  {
+    "Make all columns in the generated database schema allow \cb{NULL}
+     values. This is primarily useful in schema migration since SQLite
+     does not support dropping of columns. By making all columns \cb{NULL}
+     we can later \"delete\" them by setting their values to \cb{NULL}.
+     Note that this option overrides even the \cb{not_null} pragma."
+  };
+
   bool --sqlite-lax-auto-id
   {
     "Do not force monotonically increasing automatically-assigned
diff --git a/odb/relational/model.hxx b/odb/relational/model.hxx
index c50b6b5..5936ed1 100644
--- a/odb/relational/model.hxx
+++ b/odb/relational/model.hxx
@@ -102,20 +102,18 @@ namespace relational
       virtual bool
       traverse_column (semantics::data_member& m, string const& name, bool)
       {
-        bool id (object_columns_base::id ());             // Id or part of.
-        bool null (!id && object_columns_base::null ());
-
         string col_id (id_prefix_ +
                        (key_prefix_.empty () ? m.name () : key_prefix_));
 
         sema_rel::column& c (
-          model_.new_node<sema_rel::column> (col_id, column_type (), null));
+          model_.new_node<sema_rel::column> (
+            col_id, column_type (), null (m)));
         c.set ("cxx-location", m.location ());
         model_.new_edge<sema_rel::unames> (table_, c, name);
 
         // An id member cannot have a default value.
         //
-        if (!id)
+        if (!object_columns_base::id ())
         {
           string const& d (default_ (m));
 
@@ -134,6 +132,12 @@ namespace relational
         return true;
       }
 
+      virtual bool
+      null (semantics::data_member&)
+      {
+        return !object_columns_base::id () && object_columns_base::null ();
+      }
+
       virtual string
       default_null (semantics::data_member&)
       {
diff --git a/odb/relational/sqlite/model.cxx b/odb/relational/sqlite/model.cxx
index 78977cc..63a5302 100644
--- a/odb/relational/sqlite/model.cxx
+++ b/odb/relational/sqlite/model.cxx
@@ -23,6 +23,12 @@ namespace relational
       {
         object_columns (base const& x): base (x) {}
 
+        virtual bool
+        null (semantics::data_member& m)
+        {
+          return options.sqlite_override_null () || base::null (m);
+        }
+
         virtual string
         default_enum (semantics::data_member& m, tree en, string const&)
         {
-- 
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