def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def edit_group(group_id):
    group = Group.query.filter_by(id=group_id).first_or_404()

    form = EditGroupForm(group)

    if form.validate_on_submit():
        form.populate_obj(group)
        group.save()

        if group.guest:
            Guest.invalidate_cache()

        flash(_("Group updated."), "success")
        return redirect(url_for("management.groups", group_id=group.id))

    return render_template("management/group_form.html", form=form,
                           title=_("Edit Group"))