In a previous article I outlined how to send a message from server-side code, such as from a process script task, an entity subprocess, or a configuration service, and receive this message in client-side code. This article will show how to receive server messages in a Freedom UI. Refer to the previous article to see how to send the message in server-side code (this article will only focus on receiving the message in the Freedom UI page)

Sending a Message from Server-Side C# to Client-Side Javascript in Creatio

First of all, there might be different ways to do this in a Freedom UI page. Since Freedom UI pages are relatively new, I’m still discovering things about different ways to do things using a newer method specifically for Freedom UI. However, this equivalent of the previous method does work as expected.

To receive a server message in client-side code, you need to register a function to receive the message, but you also need to unregister it when the page gets destroyed as well. In a Freedom UI page, you’re working with “handlers”, not functions. So, in order to keep a reference to the function registered, so we can later unregister it, we’ll use an attribute to save the function in. In the page code, locate the viewModelConfig. If there’s already an “attributes” node, we’ll add our attribute under that. If there isn’t an “attributes” node, we’ll add that first. We’ll be calling our attribute “ServerMessageReceivedFunc”. The attribute will look like the following:

viewModelConfig: /**SCHEMA_VIEW_MODEL_CONFIG*/{
	"attributes": {
		"ServerMessageReceivedFunc": {}
	}
}/**SCHEMA_VIEW_MODEL_CONFIG*/,

Now add a handler for the “crt.HandleViewModelInitRequest” request, which is similar to the onEntityInitialized. In it, you’ll create a function and place in that attribute, then wire it up for receiving server messages:

{
	request: "crt.HandleViewModelInitRequest",
	handler: async (request, next) => {
		request.$context.ServerMessageReceivedFunc = function(event, message) {
			if (message.Header.Sender === "SomeMessageId") {
				// place code here to respond to the server message
				// note: inside this function, request.$context will be the `this` scope
				// for example, this.someAttributeName = "Something"
			}
		};
		Terrasoft.ServerChannel.on(Terrasoft.EventName.ON_MESSAGE, (await request.$context.ServerMessageReceivedFunc), request.$context);
		return next?.handle(request);
	}
}

Now, we’ll add the code to unregister the function when the page gets destroyed in the “crt.HandleViewModelDestroyRequest” request:

{
	request: "crt.HandleViewModelDestroyRequest",
	handler: async (request, next) => {
		Terrasoft.ServerChannel.un(Terrasoft.EventName.ON_MESSAGE, (await request.$context.ServerMessageReceivedFunc), request.$context);
		return next?.handle(request);
	}
}

As I mentioned earlier, there might be a more “Freedom UI way” to do this that I’ve not yet discovered. However for now, the above gets the job done and works great on Freedom UI pages.