Pass data to middleware further down the chain

Question

When I register middleware as part of the request pipeline, how do I pass data through the middleware chain. (ultimately accessible in an MVC controller action)

For example, I have implemented custom middleware for authenticating my requests, but how can I pass the authentication data (such as the result of the authentication and additional data) down the chain of middleware - ultimately wanting to access the data from an MVC controller action, and also in a custom MVC action filter for restricting access based on the authentication results.

Is there anywhere I can store custom data on a per-request basis, and access it later in the request chain?

Answer 1

You can use the HttpContext.Items collection to store data for the lifetime of a request. Its primary use-case is passing data around components (middleware and controllers for example). Adding and reading items is easy:

Write:

context.Items["AuthData"] = authData;

Read:

var authData = (AuthData)context.Items["AuthData"];

See the ASP.NET docs for more info.