Add method set_sequence on ModelList

This method register the current order into sequence field.

issue6133
review43501002

CHANGELOG

@@ -1,3 +1,4 @@
+* Add set_sequence method to ModelList
 * Add __int__ to Model
 * Allow to use keyword arguments with trytond configuration
 

README

@@ -106,6 +106,28 @@ The report is executed with a list of records and some extra data.
 
     >>> type_, data, print_, name = label.execute([party], {})
 
+Sorting addresses and register order
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Addresses are ordered by sequence which means they can be stored following a
+specific order. The `set_sequence` method stores the current order.
+
+    >>> address = party.addresses.new(zip='69')
+    >>> party.save()
+    >>> address = party.addresses.new(zip='23')
+    >>> party.save()
+
+Now changing the order.
+
+    >>> reversed_addresses = list(reversed(party.addresses))
+    >>> while party.addresses:
+    ...     _ = party.addresses.pop()
+    >>> party.addresses.extend(reversed_addresses)
+    >>> party.addresses.set_sequence()
+    >>> party.save()
+    >>> party.addresses == reversed_addresses
+    True
+
 Support
 -------
 

proteus/__init__.py

@@ -620,6 +620,36 @@ class ModelList(list):
         with Relation._config.set_context(self._get_context()):
             return Relation.find(new_domain, offset, limit, order)
 
+    def set_sequence(self, field='sequence'):
+        changed = False
+        prev = None
+        for record in self:
+            if prev:
+                index = getattr(prev, field)
+            else:
+                index = None
+            update = False
+            value = getattr(record, field)
+            if value is None:
+                if index:
+                    update = True
+                elif prev and record.id >= 0:
+                    update = record.id < prev.id
+            if value == index:
+                if prev and record.id >= 0:
+                    update = record.id < prev.id
+            elif value <= (index or 0):
+                update = True
+            if update:
+                if index is None:
+                    index = 0
+                index += 1
+                setattr(record, field, index)
+                changed = record
+            prev = record
+        if changed:
+            self._changed()
+
 
 class Model(object):
     'Model class for Tryton records'