IHttpForm reference
This article provides reference material about the IHttpForm interface.
Represents the posted HTTP form.

Properties
Count
The number of elements contained in the form field collection.
Files
The collection that contains uploaded files when the request includes file parts. Each file is exposed as an IHttpFile.
Keys
A collection containing the keys of the form fields.
this[string key]
Gets the value with the specified key.
Methods
ContainsKey
Determines whether the form contains an element with the specified key.
TryGetValue
Gets the value associated with the specified key. Returns true if the form object contains an element with the specified key; otherwise, false.