models.py

def full_clean(self, exclude=None, validate_unique=True):
    """
    Call clean_fields(), clean(), and validate_unique() on the model.
    Raise a ValidationError for any errors that occur.
    """
    errors = {}
    if exclude is None:
        exclude = []
    else:
        exclude = list(exclude)

    try:
        self.clean_fields(exclude=exclude)
    except ValidationError as e:
        errors = e.update_error_dict(errors)

    # Form.clean() is run even if other validation fails, so do the
    # same with Model.clean() for consistency.
    try:
        self.clean()
    except ValidationError as e:
        errors = e.update_error_dict(errors)

    # Run unique checks, but only for fields that passed validation.
    if validate_unique:
        for name in errors:
            if name != NON_FIELD_ERRORS and name not in exclude:
                exclude.append(name)
        try:
            self.validate_unique(exclude=exclude)
        except ValidationError as e:
            errors = e.update_error_dict(errors)

def clean_fields(self, exclude=None):
    """
    Clean all fields and raise a ValidationError containing a dict
    of all validation errors if any occur.
    """
    if exclude is None:
        exclude = []

    errors = {}
    for f in self._meta.fields:
        if f.name in exclude:
            continue
        # Skip validation for empty fields with blank=True. The developer
        # is responsible for making sure they have a valid value.
        raw_value = getattr(self, f.attname)
        if f.blank and raw_value in f.empty_values:
            continue
        try:
            setattr(self, f.attname, f.clean(raw_value, self))
        except ValidationError as e:
            errors[f.name] = e.error_list

    if errors:
        raise ValidationError(errors)