Replace material selection to m2o

location.py

@@ -23,7 +23,7 @@ class Location(metaclass=PoolMeta):
             'invisible': Eval('type') != 'storage',
             },
         depends=['type'])
-    material = fields.Selection('get_materials', "Material",
+    material = fields.Many2One('stock.location.material', "Material",
         states=tank_states, depends=tank_depends)
     uom = fields.Many2One('product.uom', 'Uom',
         states=tank_states, depends=tank_depends)
@@ -34,15 +34,6 @@ class Location(metaclass=PoolMeta):
         digits=(16, Eval('unit_digits', 2)),
         states=tank_states, depends=['unit_digits', 'tank'])
 
-    @classmethod
-    def get_materials(field_name):
-        pool = Pool()
-        LocationMaterial = pool.get('stock.location.material')
-        materials = [(None, "")]
-        for material in LocationMaterial.search([]):
-            materials.append((material.name, material.name))
-        return materials
-
     @fields.depends('uom')
     def on_change_with_unit_digits(self, name=None):
         if self.uom:

production.py

@@ -461,8 +461,6 @@ class Production(metaclass=PoolMeta):
         WineAgingHistory = pool.get('wine.wine_aging.history')
         LocationMaterial = pool.get('stock.location.material')
 
-        materials = dict((x.name, x) for x in LocationMaterial.search([]))
-
         today = Date.today()
         histories = WineAgingHistory.search([
             ('product', '=', input.product),
@@ -473,7 +471,7 @@ class Production(metaclass=PoolMeta):
             new_histories += WineAgingHistory.create([{
                 'production': output.production_output,
                 'location': output.to_location,
-                'material': materials.get(output.to_location.material),
+                'material': output.to_location.material,
                 'product': output.product,
                 'date_start': output.production_output.effective_date,
                 'date_end': None