Скачать или смотреть Resolving the Issue of null IP Address in Blazor Server-Side Applications

Discover why you're getting a `null` IP address in your Blazor server-side application and how to effectively resolve this common issue with `IHttpContextAccessor`.
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This video is based on the question https://stackoverflow.com/q/64530246/ asked by the user 'Melon NG' ( https://stackoverflow.com/u/7697261/ ) and on the answer https://stackoverflow.com/a/67816790/ provided by the user 'spud' ( https://stackoverflow.com/u/1565401/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Problem: null IP in Blazor Server-Side

If you've ever encountered a situation in your Blazor server-side application where the IHttpContextAccessor returns a null IP address, you're not alone. This issue is particularly problematic if you need to fetch the client's IP for functionalities such as limiting form submissions per day.

Given that your project is running on .NET 5 and you've configured the necessary services in your Startup.cs, the source of the problem can often be elusive. In this guide, we will dissect the potential causes and guide you through an effective solution to rectify this issue.

Why Does IHttpContextAccessor Return a null IP?

In a Blazor server-side app, the IHttpContextAccessor serves as a bridge to the HTTP context, which includes information about the current request such as headers, cookies, and the remote IP address. However, when deployed, the environment can alter how these values are accessed, leading to a null response.

Common reasons include:

Incorrect Configuration: Not properly setting up IHttpContextAccessor in your ConfigureServices.

Execution Context: Running the code outside the scope of a valid HTTP request.

Now, let’s look at the solution step by step.

Solution: Capturing Remote IP Address in Blazor Server

Step 1: Configure Services

Ensure that your Startup.cs has the following service registrations:

[[See Video to Reveal this Text or Code Snippet]]

The AddHttpContextAccessor method allows your Blazor components to access the current HTTP context, which is essential for fetching the IP address.

Step 2: Create the IRememberMe Interface

Define an interface that will allow you to store the IP address across requests:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Update the _Host.cshtml.cs

To actually access the IP address during the HTTP request cycle, update your _Host.cshtml.cs file like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Utilize the IP in Your Components

Now, you can leverage the stored IP address in any Blazor component. For example, if you want to display the IP address on the "About" page, you can do the following:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following these steps, you can successfully obtain the remote IP address in your Blazor server-side application. It’s important to remember that while storing IP for limiting submissions is a common workaround, relying solely on IP addresses for user identification has its own risks and limitations. Always ensure that you're taking appropriate measures to secure user data.

With this solution, you should no longer see a null IP address in your application. Happy coding!