[FIX] fields: handle the case of fields declared with store=False

Those fields should be considered as "dummy" fields": they are typically useful
for hackish onchange methods that need to store something into a form.

openerp/addons/test_new_api/models.py

@@ -31,6 +31,7 @@ class Category(models.Model):
     name = fields.Char(required=True)
     parent = fields.Many2one('test_new_api.category')
     display_name = fields.Char(compute='_compute_display_name', inverse='_inverse_display_name')
+    dummy = fields.Char(store=False)
 
     @api.one
     @api.depends('name', 'parent.display_name')     # this definition is recursive

openerp/addons/test_new_api/tests/test_new_fields.py

@@ -61,6 +61,13 @@ class TestNewFields(common.TransactionCase):
 
     def test_10_non_stored(self):
         """ test non-stored fields """
+        # a field declared with store=False should not have a column
+        field = self.env['test_new_api.category']._fields['dummy']
+        self.assertFalse(field.store)
+        self.assertFalse(field.compute)
+        self.assertFalse(field.inverse)
+        self.assertFalse(field.column)
+
         # find messages
         for message in self.env['test_new_api.message'].search([]):
             # check definition of field

openerp/addons/test_new_api/views.xml

@@ -173,6 +173,7 @@
                         <group>
                             <field name="name"/>
                             <field name="parent"/>
+                            <field name="dummy"/>
                         </group>
                     </sheet>
                 </form>

openerp/fields.py

@@ -671,7 +671,7 @@ class Field(object):
 
     def to_column(self):
         """ Return a column object corresponding to `self`, or ``None``. """
-        if not self.store and self.compute:
+        if not self.store and (self.compute or not self.column):
             # non-stored computed fields do not have a corresponding column
             self.column = None
             return None