# QnA Model

path: `/qna/models.py`. Keeping qna and record of coach taking qna  

## Models  

### QNA model

each entry is one posts  
- `content_type` indicates whether an entry is Q&A or Editorial  
- `prediction`, `assignment` => related to meta.Category  
- `tag` => many-to-many related to meta.QNATag  
- `asked_by` (user), `answer_by` (coach) => related to user.User (if content_type == Editorial, asked_by will be null)  
- `alias` => unique for querying posts

- `approved_question` indicates whether a QNA is valid for coach to answer. If user asked QNA without quota, `approved_question` will be `false` and the question will not be seen by coach  
- `published` indicates whether a question is public. `true` when the QNA is answered by a coach  
- `approved question` and `published` will be `true` when it is an editorial  

### QNAOrder model
- `qna` => related to qna.QNA  
- `coach` => related to user.User  
- `status` => string  

| Value | Description | Meaning |
| :--- | :---- | :--- |
| PD | Pending (default) | the coach has taken the QNA but not answered yet  |
| CP | Completed | the coach answered the QNA      |
| CL | Cancelled | the coach cancelled the order or the order expired      |

a crontab is set to check all pending QNAOrder for every two hours. Any expired order will be set `cancelled` automatically  
>expiry time: 1 day