How come in the Trigger and Binding table, the Events, Queues and Topics are only listed as Triggers and Output, but not Input?
When invoking a Queue-triggered function, the function is provided the value of the item that caused the trigger to be invoked. This is the same behavior for a Blob, which does have trigger, input and output.
Just looking for clarification, as I might be misunderstanding something.
I believe this is work in progress. E.g. Storage Queue input bindings are supported, but not documented:
while Service Bus input bindings are not supported yet.
In any case, there is a significant difference with Blob binding. For a Blob input binding, you can specify which blob item to inject to the function based on parameters of the input trigger, e.g. calculate blob path from HTTP parameters or event fields.
That doesn't make much sense for queues, as there's no random item access in queues. So, you can instead bind the name of the queue, not the path to queue message. You then inject a CloudQueue class, as shown in this answer.
