How to get a base url for Asp.Net Core Application in the Razor View Page

How to get a base url for Asp.Net Core Application in the Razor View Page

Title
Retrieving the Base URL of an ASP.NET Core Application in Razor Pages
A Comprehensive Guide

ASP.NET Core is an open-source, cross-platform framework developed by Microsoft for building modern web applications. One common requirement while developing web applications is to access the application's base URL from within the application itself. In this blog post, we will explore how to retrieve the base URL of an ASP.NET Core application in Razor Pages using various methods.

First, let's understand why we might need the base URL of our application. The base URL is essential for constructing absolute URLs for various resources such as images, stylesheets, scripts, or APIs that our application may require. In Razor Pages, we can use this base URL to build URLs dynamically or to configure third-party libraries that need it.

There are several ways to retrieve the base URL of an ASP.NET Core application in Razor Pages. In this blog post, we will cover three methods
using the `IWebHelper`, using the `HttpContext`, and using environment variables.

**Method 1
Using IWebHelper**

The `IWebHelper` interface is part of the ASP.NET Core MVC framework and provides various methods for working with URLs. We can use it to retrieve the application's base URL in Razor Pages as well.

First, let's create an extension method to simplify accessing the `IWebHelper` instance from within a Razor Page. Add a new file named `Extensions.cs` to your `Pages` folder with the following content

csharp
using Microsoft.AspNetCore.Mvc;
public static class Extensions
{
    public static IWebHelper WebHelper(this IPageContext pageContext)
    {
        return pageContext.GetEndpoint()?.Metadata.GetMetadata() as IWebHelper;
    }
}

Now, we can use this extension method to retrieve the `IWebHelper` instance from any Razor Page by injecting `IPageContext` into the constructor.

csharp
using Microsoft.AspNetCore.Mvc.RazorPages;
using Microsoft.AspNetCore.Mvc;
public class IndexModel 
 PageModel
{
    public string BaseUrl { get; private set; }
    public IndexModel(IPageContext pageContext)
    {
        BaseUrl = pageContext.WebHelper().GetBaseUrl();
    }
}

In this example, we inject `IPageContext` into the constructor of our `IndexModel` class and use the `Extensions.WebHelper()` method to retrieve the `IWebHelper` instance. We then call the `GetBaseUrl()` method on `IWebHelper` to get the application's base URL.

**Method 2
Using HttpContext**

Another way to retrieve the base URL of an ASP.NET Core application is by using the `HttpContext` object. The `HttpContext` provides access to various HTTP-related information, including the request's URL.

csharp
using Microsoft.AspNetCore.Mvc.RazorPages;
public class IndexModel 
 PageModel
{
    public string BaseUrl { get; private set; }
    public IndexModel(IHttpContextAccessor httpContextAccessor)
    {
        BaseUrl = httpContextAccessor.HttpContext.Request.Scheme + "
//" + httpContextAccessor.HttpContext.Request.Host;
    }
}

In this example, we inject `IHttpContextAccessor` into the constructor of our `IndexModel` class and use it to access the `HttpContext` object. We then construct the base URL by combining the scheme (HTTP or HTTPS), the domain name, and the port number (if any) from the `HttpContext` object.

**Method 3
Using Environment Variables**

ASP.NET Core applications support configuring various settings using environment variables. We can store the application's base URL as an environment variable and retrieve it within our Razor Pages using the `IConfiguration` interface.

First, add the following line to your `appsettings.json` file

json
"BaseUrl"
 "https
//yourapp.com"

Next, create a new file named `appsettings.Development.json` (or `appsettings.Production.json` for production environments) with an empty content. This file will be