ASP.net MVC - request-scoped global variable

Question

I have a value which I want to be vaild during a single request. I am not using Session, as this would make the value global for the entire navigation session.

So I have put thie value in a static field of a class. Great, but then I discovered that such fields are even more global, that is, they stay set for the entire application! This means that there could be random interaction among navigation sessions.

So the question is: is there a safe place I can put a global variable, which will be

• global throughout the request
• reset after the request is completed
• not affected by any other request, either of the same user or by other users

Thanks Palantir

EDIT I'll elaborate. I have a piece of code in my master page, which I need to hide on certain conditions, of which I am aware in the controller only. I thought about setting a static variable in the controller, which then would be queried by the master page, but now I see there could be a better way...

Answer 1

Use HttpContext.Items - a per-request cache store. Check out this article on 4guysfromrolla for more details.

It should work fine in ASP.NET MVC. You may wish to derive your master page from a base class (either via code-behind or using the Inherits directive) and have a protected method on the base class that inspects HttpContext.Items and returns, e.g. true/false depending whether you want to display the conditional code.

Answer 2

TempData lasts until the next request as already noted.

But there are also two other dictionaries scoped to the single request.

• {Controller,ViewPage}.ViewData
• Context.Items

To communicate from controller to (master) page ViewData is probably the better choice.