Django TypeError“期望的字符串或缓冲区”

Question

I have no idea where is mistake. I get error "expected string or buffer", when i'm trying to get date from form.

Model:

class Trip(models.Model):
    creator = models.ForeignKey(Person, on_delete=models.CASCADE, default=None)
    name = models.CharField(max_length=200)
    start_time = models.DateField()
    end_time = models.DateField()

Form:

class TripForm(forms.Form):
    name = forms.RegexField(regex=r'^\w+$', widget=forms.TextInput(attrs=dict(required=True, max_length=30)), label=_("Name"), error_messages={ 'invalid': _("This value must contain only letters, numbers and underscores.") })
    start_time = DateTimeField(widget=forms.widgets.DateInput(format="%d %b %Y" ) )
    end_time = DateTimeField(widget=forms.widgets.DateInput(format="%d %b %Y"))

And in view im extracting date like that:

   start_time=trip_form['start_time'],
   end_time=trip_form['end_time'],

in html im creating input_place like that:

<div>
      Planned end day of the Trip:
      {{ trip_form.end_time|attr:"type:date" }}
</div>

Any ideas?

I have to admit is very hard to find good datetimepicker/datepicker.

Traceback:

File "D:\Program Files\Python27\lib\site-packages\django\core\handlers\base.py" in get_response
  149.                     response = self.process_exception_by_middleware(e, request)

File "D:\Program Files\Python27\lib\site-packages\django\core\handlers\base.py" in get_response
  147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "D:\Program Files\Python27\lib\site-packages\django\utils\decorators.py" in _wrapped_view
  149.                     response = view_func(request, *args, **kwargs)

File "D:\Program Files\Python27\lib\site-packages\django\contrib\auth\decorators.py" in _wrapped_view
  23.                 return view_func(request, *args, **kwargs)

File "D:\Workspaces\TravelBuddyDj\TravelBuddy\views.py" in add_trip
  113.                 end_time=trip_form['end_time'],

File "D:\Program Files\Python27\lib\site-packages\django\db\models\manager.py" in manager_method
  122.                 return getattr(self.get_queryset(), name)(*args, **kwargs)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\query.py" in create
  401.         obj.save(force_insert=True, using=self.db)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\base.py" in save
  700.                        force_update=force_update, update_fields=update_fields)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\base.py" in save_base
  728.             updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\base.py" in _save_table
  812.             result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\base.py" in _do_insert
  851.                                using=using, raw=raw)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\manager.py" in manager_method
  122.                 return getattr(self.get_queryset(), name)(*args, **kwargs)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\query.py" in _insert
  1039.         return query.get_compiler(using=using).execute_sql(return_id)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\sql\compiler.py" in execute_sql
  1059.             for sql, params in self.as_sql():

File "D:\Program Files\Python27\lib\site-packages\django\db\models\sql\compiler.py" in as_sql
  1019.                 for obj in self.query.objs

File "D:\Program Files\Python27\lib\site-packages\django\db\models\sql\compiler.py" in prepare_value
  958.             value = field.get_db_prep_save(value, connection=self.connection)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\fields\__init__.py" in get_db_prep_save
  728.                                       prepared=False)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\fields\__init__.py" in get_db_prep_value
  1301.             value = self.get_prep_value(value)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\fields\__init__.py" in get_prep_value
  1296.         return self.to_python(value)

File "D:\Program Files\Python27\lib\site-packages\django\db\models\fields\__init__.py" in to_python
  1260.             parsed = parse_date(value)

File "D:\Program Files\Python27\lib\site-packages\django\utils\dateparse.py" in parse_date
  60.     match = date_re.match(value)

Exception Type: TypeError at /addtrip/
Exception Value: expected string or buffer

Answer 1

The error is coming from django.util.dateparse.parse_date so make sure your date is properly formatted.

Here is the regex parse_date is using to figure out the date, make sure your input is in this format (string 'YYYY-MM-DD'):

date_re = re.compile(
    r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$'
)

You will likely have to configure your date picker to give you the date in this format, or write a bit of javascript to output your date value in the string format Django is expecting.

None should also be OK (at least it shouldn't produce this error), although based on your model the database will likely complain about that value.