'Shelter Flag form validation:
- if create_task=True, then task_description is required'

@staticmethod
def shelter_flag_onvalidation(form):

    T = current.T
    formvars = form.vars
    create_task = formvars.get('create_task')
    task_description = formvars.get('task_description')
    if (create_task and (not task_description)):
        form.errors['task_description'] = T('Task    Description    required')
