# Preface
This tutorial is based on the "apifm-wxapi" module and teaches you how to quickly implement small program development, so you may need to understand the following knowledge points first:
["Creating HelloWorld Project"](https://www.yuque.com/apifm/doc/hezlrm)
["Use "apifm-wxapi" to quickly develop small programs"](https://www.yuque.com/apifm/doc/mdldsd)
["Register for free to open the backend and obtain an exclusive domain name"](https://www.yuque.com/apifm/doc/qr6l4m)
In this case, some functions require the user to log in before they can be operated, which means token authorization is required. Please understand first:
["WeChat Mini Program login to obtain openid and third-party tokens"](https://www.yuque.com/apifm/doc/kaygbw)
# Modules that need to be enabled
Log in to the "First Step" registration background, left menu --> Factory settings --> Module management
Find and enable the following modules, then press F5 to refresh the background interface. You will be able to see all the function menus required for this case:
_The menu in this case is "Mall Management" --> "Knowledge Transaction Settings" + "Knowledge Transaction Record"_
1. Knowledge trading
---
### Product List
```javascript
WXAPI.virtualTraderList(Object object)
```
> Please refer to the interface document for specific parameters.
>
> It is recommended that this function be used in conjunction with the CMS system, which can achieve better pre-purchase information display and give users enough reference to consider purchasing.
>
### Product details
```javascript
WXAPI.virtualTraderDetail(token, id)
```
> Read product details data
>
> Paid attributes and payment details will be returned only after purchase.
>
> So you can use this function to implement post-purchase reading and post-purchase playback applications.
>
### Purchase items
```javascript
WXAPI.virtualTraderBuy(token, id)
```
> Use user balance to purchase knowledge paid products
>
> How to use online payment, please view the instructions for using nextAction in the online payment function
>
### My purchase history
```javascript
WXAPI.virtualTraderMyBuyLogs(Object object)
```
> Please refer to the interface document for specific parameters.
>
> All paid knowledge records I have purchased
>
**For more detailed parameter usage and more advanced advanced usage methods, please refer to the API interface documentation: **
["api interface document"](#)
_More usage methods about apifm-wxapi: _
["apifm-wxapi Instructions for Use"](https://github.com/gooking/apifm-wxapi/blob/master/instructions.md)
_Download the Demo code of this case: _
["apifm-wxapi using Demo program"](https://github.com/gooking/apifm-wxapi-demo)
Looking forward to your progress!
Thanks!