Implementing Content Negotiation for Flexible Data Formats

Content negotiation in ASP.NET Core is crucial for serving different data formats like JSON, XML, etc., based on the client's preferences. Here's a complete example of how to implement content negotiation in an ASP.NET Core Web API.

Step 1. Create a new ASP.NET Core Web API project using Visual Studio or the .NET CLI

Create the new Asp.Net Core Web API Project Using Asp.Net Core Web API 

Step 2. Create a model class, for instance, named MudassarInformation.cs

public class MudassarInformation
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

Step 3. Configure the Startup.cs file to support content negotiation

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

public class Startup
    public IConfiguration Configuration { get; }

    public Startup(IConfiguration configuration)
        Configuration = configuration;

    public void ConfigureServices(IServiceCollection services)

        // Configure content negotiation
        services.AddMvc(options =>
            options.RespectBrowserAcceptHeader = true;
            options.ReturnHttpNotAcceptable = true;

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        if (env.IsDevelopment())


        app.UseEndpoints(endpoints =>

Step 4. Create a controller that responds to different data formats

using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;

public class MudassarInformationController : ControllerBase
    private static List<MudassarInformation> _data = new List<MudassarInformation>
        new MudassarInformation { Id = 1, Name = "Mudassar 1", Description = "Information about Mudassar 1" },
        new MudassarInformation { Id = 2, Name = "Mudassar 2", Description = "Information about Mudassar 2" }

    public IActionResult Get()
        return Ok(_data);

Step 5. Test the content negotiation using tools like Postman or a web browser

Set the Accept header to specify the desired format. For JSON, set Accept: application/json. For XML, set Accept: application/xml.

By following these steps, you've customized the example to use the "MudassarInformation" model name while still implementing content negotiation to return different data formats based on client preferences.


content negotiation in ASP.NET Core Web APIs is a powerful feature that allows you to serve different data formats (such as JSON or XML) based on the client's preferences. This flexibility ensures that your API can cater to a variety of clients, each expecting data in their preferred format. Here's a recap of the key points covered in the example:

  1. Model Definition: Defining your model class, in this case, "MudassarInformation," is the foundation for the data you'll be serving through your API.
  2. Content Negotiation Configuration: In the Startup.cs file, configuring content negotiation through the MVC options enable your API to automatically determine the appropriate data format based on the Accept header in the client's request.
  3. Controller Implementation: Creating a controller that responds to different data formats demonstrates how your API can provide data in both JSON and XML formats. This flexibility is especially useful when clients have diverse data consumption requirements.
  4. Testing and Usage: with tools like Postman or web browsers, you can verify that your API delivers responses in the expected format based on the client's preferences, as indicated by the `Accept` header.

Content negotiation enhances the usability and accessibility of your Web API, allowing different clients to communicate effectively regardless of their preferred data format. This feature is particularly important in today's interconnected and diverse application landscape. By incorporating content negotiation into your ASP.NET Core Web API development, you empower your API to serve a broader audience and enhance the overall user experience.

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