MessageHandler

The MessageHandler is used to handle messages from the WeChat public number dialogue window.

The SDK has all the basic functionality needed for the developer, the developer just needs to create a custom subclass to supplement the business logic that needs to be customised.

Custom MessageHandler

In the current example, we named our custom MessageHandler CustomMessageHandler.

CustomMessageHandler.cs Reference file for this project:

/MessageHandlers/ directory CustomMessageHandler.cs MessageHandler main file + General Message Handling CustomMessageHandler_Events.cs MessageHandler Event Message Handler CustomMessageContext.cs Custom rewrite of DefaultMpMessageContext context (optional)

Of all the override methods demonstrated in CustomMessageHandler*.cs, only the DefaultResponseMessage() method is required to be overridden, and all the other OnXxxRequest() methods are optional, so that when a message is sent by a user, and the corresponding override method cannot be found, then the DefaultMpMessage() method is called. When the user sends a message and can't find a corresponding override method, the DefaultResponseMessage() method will be called.

The MessageHandler has two ways of carrying the message so that it can be accessed externally (by the WeChat server) via a URL. These are the Middleware method (recommended) and the Controller method. The CustomMessageHandler used by both methods is common, so it can be switched and co-exist at any time.

Middleware way to host MessageHandler

The middleware approach is the recommended and simplest way to introduce middleware without creating any new files, just below the Program.cs file after all Senparc.Weixin registration code has been executed:

app.UseMessageHandlerForMp(
  "/WeixinAsync",
  CustomMessageHandler.GenerateMessageHandler,
  (options) => {
    options.AccountSettingFunc = (context) =>
      Senparc.Weixin.Config.SenparcWeixinSetting;
  }
);

Once done, the MessageHandler can be accessed via Url Domain/WeixinAsync, set to the message URL of the public backend.

test /WeixinAsync (opens new window)

Reference document for this project:

/Program.cs

For more middleware approaches, please refer to: "Using MessageHandler Middleware in .NET Core 2.0/3.0" (opens new window) (also applicable to . 6.0 and above).

Controller approach to hosting MessageHandler

When the middleware approach doesn't meet your needs, you can use a Controller to "unfold" the execution process and control or intervene more precisely at each step of the execution.

To use Controller, you need to create 2 Actions, which correspond to WeChat background authentication (Get request) and real message push (Post request). The project example is located in WeixinController.cs.

WeixinController.cs Reference file for this project:

/Controllers/WeixinController.cs

Once done, you can access MessageHandler via Url Domain/Weixin, set as the message URL of public backend.

Test /Weixin (opens new window)

For more Controller methods, please refer to: "Understanding MessageHandler" (opens new window) (Recommended to use full set of asynchronous methods)