ASP.NET MVC / Web API : How to Set a Default Header with a Token, to be Used Across Different Controller Class?

If you’re building a web application using ASP.NET MVC or Web API, you might have come across a scenario where you need to set a default header with a token that can be used across different controller classes. This is a common requirement, especially when working with APIs that require authentication or authorization tokens to be sent with each request.

In this article, we’ll explore how to achieve this in ASP.NET MVC and Web API, and provide you with a comprehensive guide on how to set a default header with a token that can be used across different controller classes.

Why Do We Need to Set a Default Header with a Token?

Before we dive into the implementation, let’s understand why we need to set a default header with a token in the first place.

Imagine you’re building a web application that provides a set of APIs to perform various operations, such as creating, reading, updating, and deleting data. To secure these APIs, you decide to implement authentication and authorization using tokens. With this approach, each request sent to the API should include a valid token that authenticates the user and authorizes access to the requested resource.

However, including the token in each request can become cumbersome, especially if you have multiple APIs and controllers that need to send the token with each request. This is where setting a default header with a token comes into play.

How to Set a Default Header with a Token in ASP.NET MVC

In ASP.NET MVC, you can set a default header with a token using the `System.Net.Http.Headers` namespace. Specifically, you can use the `HttpRequestMessage.Headers` property to set the default header.

Using a Base Controller Class

One way to set a default header with a token in ASP.NET MVC is to create a base controller class that inherits from `System.Web.Mvc.Controller`. This base controller class can set the default header with the token in its constructor.

public abstract class BaseController : Controller
{
    protected BaseController()
    {
        var token = "your_token_here"; // retrieve the token from a secure storage
        HttpContext.Current.Request.Headers.Add("Authorization", $"Bearer {token}");
    }
}

In the above code, we’re adding the `Authorization` header with the token to the `HttpContext.Current.Request.Headers` collection in the base controller class’s constructor. This way, every controller that inherits from the base controller class will have the default header set with the token.

Using a Filter

Another way to set a default header with a token in ASP.NET MVC is to use a filter. You can create a custom filter class that implements the `System.Web.Http.Filters.IActionFilter` interface, and sets the default header with the token in the `OnActionExecuting` method.

public class TokenFilter : IActionFilter
{
    public void OnActionExecuting(ActionExecutingContext filterContext)
    {
        var token = "your_token_here"; // retrieve the token from a secure storage
        filterContext.HttpContext.Request.Headers.Add("Authorization", $"Bearer {token}");
    }

    public void OnActionExecuted(ActionExecutedContext filterContext)
    {
        // no-op
    }
}

In the above code, we’re adding the `Authorization` header with the token to the `filterContext.HttpContext.Request.Headers` collection in the `OnActionExecuting` method. This filter can then be applied to individual controllers or actions using the `[TokenFilter]` attribute.

How to Set a Default Header with a Token in ASP.NET Web API

In ASP.NET Web API, you can set a default header with a token using the `System.Net.Http.Headers` namespace. Specifically, you can use the `HttpRequestMessage.Headers` property to set the default header.

Using a DelegatingHandler

One way to set a default header with a token in ASP.NET Web API is to create a delegating handler that sets the default header with the token. A delegating handler is a class that inherits from `System.Net.Http.DelegatingHandler`, and can be used to modify the outgoing request.

public class TokenDelegatingHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var token = "your_token_here"; // retrieve the token from a secure storage
        request.Headers.Add("Authorization", $"Bearer {token}");
        return await base.SendAsync(request, cancellationToken);
    }
}

In the above code, we’re adding the `Authorization` header with the token to the `request.Headers` collection in the `SendAsync` method. This delegating handler can then be added to the Web API pipeline to set the default header with the token for all outgoing requests.

Using a MessageHandler

Another way to set a default header with a token in ASP.NET Web API is to use a message handler. A message handler is a class that inherits from `System.Net.Http.HttpMessageHandler`, and can be used to modify the outgoing request.

public class TokenMessageHandler : HttpMessageHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var token = "your_token_here"; // retrieve the token from a secure storage
        request.Headers.Add("Authorization", $"Bearer {token}");
        return await base.SendAsync(request, cancellationToken);
    }
}

In the above code, we’re adding the `Authorization` header with the token to the `request.Headers` collection in the `SendAsync` method. This message handler can then be added to the Web API pipeline to set the default header with the token for all outgoing requests.

Best Practices and Considerations

When setting a default header with a token in ASP.NET MVC or Web API, there are several best practices and considerations to keep in mind:

• Security: Make sure to store the token securely, such as using a secure storage like Azure Key Vault or a secrets manager.
• Token Expiry: Implement token expiry and renewal mechanisms to ensure that the token is valid and up-to-date.
• Token Validation: Validate the token on each request to ensure it’s valid and not tampered with.
• Error Handling: Handle errors and exceptions properly when setting the default header with the token.
• Performance: Consider the performance impact of setting the default header with the token, especially if you have a high volume of requests.

Conclusion

In conclusion, setting a default header with a token in ASP.NET MVC and Web API can be achieved using various approaches, including using a base controller class, filters, delegating handlers, and message handlers. By following the best practices and considerations outlined in this article, you can ensure that your web application is secure, scalable, and maintainable.

Remember to always prioritize security and follow the principle of least privilege when working with tokens and authentication mechanisms.

Approach	ASP.NET MVC	ASP.NET Web API
Base Controller Class	✔	✘
Filter	✔	✘
Delegating Handler	✘	✔
Message Handler	✘	✔

This table summarizes the approaches discussed in this article, indicating which ones are applicable to ASP.NET MVC and ASP.NET Web API.

Frequently Asked Question

Get ready to unlock the secrets of ASP.NET MVC and Web API! Here are the most frequently asked questions about setting default headers with tokens across different controller classes.