IFormFile binding error

Describe the bug

I have a model with IFormFIle property and other simple type properties.It could pass to the controller with [ApiController] and [FromForm] successfully.But If I only pass IFormFile property in model,it could not pass data to controller.I find a solution,when I remove [ApiController] and [FromForm],it works.

To Reproduce

using asp.net core 3.1

Model：

    public class ProductImageDetailsDto
    {
        public IFormFile ProductImage { get; set; }

        public bool IsDefaultImage { get; set; }

    }

Controller:

    [ApiController]
    [Route("[controller]")]
    public class WeatherForecastController : ControllerBase
    {
        [HttpPut("UpdateProductImagesByProductId/{id}")]
        public async Task<IActionResult> UpdateProdutImagesByProductId(Guid id,[FromForm]List<ProductImageDetailsDto> productImages)
        {

            return Ok();
        }
    }

SO Reference:

https://stackoverflow.com/questions/65085522/how-to-upload-multiple-files-using-multipart-form-data-media-type-in-net-core-w/65087114

[daping123]

Thank you for filing this issue. In order for us to investigate this issue, please provide a minimalistic repro project (ideally a GitHub repo) that illustrates the problem.

@mkArtakMSFT I have create a github repo here: https://github.com/daping123/ModelBindingProj

When you post only ProductImage in postman,I will receive data count=0. When you post both ProductImage and IsDefaultImage,I will receive the correct data.

Why?Does IFormFile run the different pipeline in model binding?And my workaround is that,when I remove [ApiController] and [FromForm], I could pass ProductImage without IsDefaultImage.For my workaround,i am also confused,why i can’t add [FromForm]?

And I find if I receive Model instead of List<Model> in backend.Using [FromForm] is OK.

[coderealm]

I have spent the last 3 days looking to find how others have solved this problem but nothing out there works. Guess it is bug. When will this be released to production please?