Parse text as datetime when it is a string

The on_paste method is calling value_from_text for each widget using the
string from the clipboard.
So textual value needs to be supported even for date and time widgets which
uses a cell renderer that provides datetime value.

Closes #12860
(grafted from 06448d7bdb976b7057a465ca332bbc638e91653e)

--HG--
branch : 6.0

tryton/tryton/common/datetime_.py

@@ -10,7 +10,9 @@ from dateutil.parser import parse
 
 from .common import IconFactory
 
-__all__ = ['Date', 'CellRendererDate', 'Time', 'CellRendererTime', 'DateTime']
+__all__ = [
+    'Date', 'CellRendererDate', 'Time', 'CellRendererTime', 'DateTime',
+    'date_parse']
 
 _ = gettext.gettext
 

tryton/tryton/gui/window/view_form/view/list_gtk/widget.py

@@ -28,7 +28,8 @@ from tryton.common import data2pixbuf
 from tryton.common.completion import get_completion, update_completion
 from tryton.common.selection import (
     SelectionMixin, PopdownMixin, selection_shortcuts)
-from tryton.common.datetime_ import CellRendererDate, CellRendererTime
+from tryton.common.datetime_ import (
+    CellRendererDate, CellRendererTime, date_parse)
 from tryton.common.domain_parser import quote
 from tryton.config import CONFIG
 
@@ -474,6 +475,17 @@ class Date(GenericText):
         else:
             return ''
 
+    def value_from_text(self, record, text, callback=None):
+        if isinstance(text, str):
+            field = record[self.attrs['name']]
+            try:
+                # Use a datetime instance and rely on field to convert to the
+                # proper type
+                text = date_parse(text, self.get_format(record, field))
+            except (ValueError, OverflowError):
+                text = None
+        return super().value_from_text(record, text, callback=callback)
+
 
 class Time(Date):