Support strongly typed event data

[drub0y]

Currently EventGridEvent is designed with its Data property as a JObject which will force everyone downstream to get into dealing with converting that into their own strong types using the JSON.NET APIs themselves.

I propose supporting an EventGridEvent<T> where the Data property would now be T. This would allow people to use a parameter such as EventGridEvent<CustomerProfileUpdated> and it would "just work". Simultaneously we can keep the existing, default EventGridEvent by simply changing it to be a subclass of EventGridEvent<JObject> that effectively locks it into JObject for people who might choose to work with that model instead.

[ChristianWeyer]

Is there anything like this planned?
.cc @fabiocav .cc @jeffhollan

[jeffhollan]

We just use the EventGrid .net SDK to surface the trigger so it’s likely a better ask for the event grid SDK team. If the SDK supported it functions would “inherit” that functionality. I’ll ping them on this ask and reference the discussion.

[adrianknight89]

@jeffhollan Can you give us an update on this? Also, I'd like to see enums for eventType. Coding against strings looks unreliable to me.

[iamalexmang]

An update would be highly appreciated, @jeffhollan.
I realize this is not in the Functions' turf, but I appreciate that you could add some weight to this.
I believe that it is childish that the event which is getting a strongly typed object must be read using a key value pair instead.
What's mostly annoying is the the only available sample using custom data literally leverages this functionality, but it fires an http-triggered function instead (which is far from ideal for the purpose of the sample): Event Grid triggered functions just be just that, not an http triggered function which pulls the event data, imho.

[jeffhollan]

Sure let me send this to the Event Grid team and see if any thoughts on what would be required here and if something that can be committed

[krb3d]

Hello there. Any updates on this topic?

[fnandocontreras]

+1 Nice to have this feature

[MattMinke]

So the EventGrid client library (NuGet: "Microsoft.Azure.EventGrid") has a EventGridSubscriber that supports the ability to add custom mappings that will be used during deserialization. With this you can then Cast the Data property to the type you are interested in. While not exactly what is being asked for this might provide the insight to someone more familiar with the inner working of Azure functions and how the EventGridTrigger works.

public void Example(System.IO.Stream inbound)
{
    var eventGridSubscriber = new Microsoft.Azure.EventGrid.EventGridSubscriber();

    eventGridSubscriber.AddOrUpdateCustomEventMapping(
        typeof(MyEvent).FullName,
        typeof(MyEvent));

    var events = eventGridSubscriber.DeserializeEventGridEvents(inbound);

    var myEvent = (MyEvent)events.First().Data;

}

NOTE: The Microsoft.Azure.EventGrid package has been deprecated in favor of Azure.Messaging.EventGrid however I think Azure functions are still using the Microsoft.Azure.EventGrid package
https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/eventgrid/Azure.Messaging.EventGrid/MigrationGuide.md#deserializing-events-and-data

Additional reference material:

• https://docs.microsoft.com/en-us/azure/event-grid/receive-events#endpoint-validation
• https://docs.microsoft.com/en-us/dotnet/api/overview/azure/eventgrid?view=azure-dotnet#consume-events
• https://github.com/Azure-Samples/azure-event-grid-viewer/blob/master/viewer/Controllers/UpdatesController.cs

[shreyabatra4]

This is available in the new version of bindings (3.x), reference here.