ASP.NET Core Middleware Passing Parameters to Controllers

Question

I am using ASP.NET Core Web API, where I have Multiple independent web api projects. Before executing any of the controllers' actions, I have to check if the the logged in user is already impersonating other user (which i can get from DB) and can pass the impersonated user Id to the actions.

Since this is a piece of code that gonna be reused, I thought I can use a middleware so:

• I can get the initial user login from request header
• Get the impesonated User Id if any
• Inject that ID in the request pipeline to make it available to the api being called

public class GetImpersonatorMiddleware
{
    private readonly RequestDelegate _next;
    private IImpersonatorRepo _repo { get; set; }

    public GetImpersonatorMiddleware(RequestDelegate next, IImpersonatorRepo imperRepo)
    {
        _next = next;
        _repo = imperRepo;
    }
    public async Task Invoke(HttpContext context)
    {
        //get user id from identity Token
        var userId = 1;

        int impersonatedUserID = _repo.GetImpesonator(userId);

        //how to pass the impersonatedUserID so it can be picked up from controllers
        if (impersonatedUserID > 0 )
            context.Request.Headers.Add("impers_id", impersonatedUserID.ToString());

        await _next.Invoke(context);
    }
}

I found this Question, but that didn't address what I am looking for.

How can I pass a parameter and make it available in the request pipeline? Is it Ok to pass it in the header or there is more elegant way to do this?

Answer 1

You can use HttpContext.Items to pass arbitrary values inside the pipeline:

context.Items["some"] = "value";