Use proper function field for history lines instead of custom One2Many for

issue1971

The field "opportunity" was not the right relation field and than the client
behaved like if it was a tree.

opportunity.py

@@ -363,18 +363,6 @@ class SaleOpportunityLine(ModelSQL, ModelView):
 SaleOpportunityLine()
 
 
-class One2ManyHistory(fields.One2Many):
-
-    def get(self, ids, model, name, values=None):
-        opportunity2id = {}
-        histories = model.browse(ids)
-        opportunity2id = dict((history.opportunity.id, history.id) for
-                history in histories)
-        res = super(One2ManyHistory, self).get(opportunity2id.keys(), model,
-                name, values=values)
-        return dict((opportunity2id[i], j) for i, j in res.iteritems())
-
-
 class SaleOpportunityHistory(ModelSQL, ModelView):
     'Sale Opportunity History'
     _name = 'sale.opportunity.history'
@@ -397,8 +385,8 @@ class SaleOpportunityHistory(ModelSQL, ModelView):
     }, depends=['state'])
     description = fields.Char('Description')
     comment = fields.Text('Comment')
-    lines = One2ManyHistory('sale.opportunity.line', 'opportunity', 'Lines',
-            datetime_field='date')
+    lines = fields.Function(fields.One2Many('sale.opportunity.line', None, 'Lines',
+            datetime_field='date'), 'get_lines')
     state = fields.Selection(STATES, 'State')
     probability = fields.Integer('Conversion Probability')
     lost_reason = fields.Text('Reason for loss', states={
@@ -442,6 +430,18 @@ class SaleOpportunityHistory(ModelSQL, ModelView):
                 (', '.join(self._table_query_group()))) % \
                 opportunity_obj._table, [])
 
+    def get_lines(self, ids, name):
+        line_obj = self.pool.get('sale.opportunity.line')
+        histories = self.browse(ids)
+        result = {}
+        # We will always have only one id per call due to datetime_field
+        for history in histories:
+            result[history.id] = line_obj.search([
+                ('opportunity', '=', history.opportunity.id),
+            ])
+        return result
+
+
     def read(self, ids, fields_names=None):
         res = super(SaleOpportunityHistory, self).read(ids,
                 fields_names=fields_names)