title: How can .NET Core's IFormFile recognise a .csv file?
body: <p>I'm trying to post a .csv file using Postman, but when I debug it always has a null value.</p>
  
  <p>I checked the csv file and it should be valid, I can open it both with Microsoft Office and Open Office.</p>
  
  <p>I sent it both as <code>form-data</code> and as a <code>binary</code> in Postman, but neither worked.</p>
  
  <p>I tried adding a <code>[FromForm]</code> attribute, like in this answer: <a href="https://stackoverflow.com/a/54570203/1984657">https://stackoverflow.com/a/54570203/1984657</a> </p>
  
  <p>I also tried as IFormFileCollection, but this didn't work either.</p>
  
  <p>Below is the stripped down code, even here it still receives a null value</p>
  
  <pre><code>namespace csvApp.Controllers
  {
      [Route("api/[controller]")]
      [ApiController]
      public class CsvController : ControllerBase
      {
          [HttpPost]
          public ActionResult Post(IFormFile csv)
          {
              return Ok(csv);
          }
      }
  }
  </code></pre>
  
  <p>What am I missing?</p>