ASP.NET Core 3.1 upload image with tinymce

Question

I'm trying to set up the image upload with tinymce but I can't get the image in the controller from the view that contains the form.

I obtaine this error message :

System.NullReferenceException : 'Object reference not set to an instance of an object.'

The images should be stored in the images folder which is in the wwwroot

js file :

tinymce.init({
            selector: '#TinyArea',
            skin: 'oxide',
            content_css: 'default',
            toolbar: 'undo redo styleselect bold italic alignleft aligncenter alignright bullist numlist outdent indent table lists code link | fullscreen preview save print | insertfile image media anchor',
            plugins: 'code emoticons imagetools preview print autosave save image link media table anchor lists checklist wordcount imagetools paste ',
            image_caption: true,
            autosave_interval: '30s',
            image_title: true,
            paste_data_images: true,
            automatic_uploads: true,
            images_upload_url: '/PropositionArticle/uploadImg',
            file_picker_types: 'image',
            file_picker_callback: function (cb, value, meta) {

                var input = document.createElement('input');
                input.setAttribute('type', 'file');
                input.setAttribute('accept', 'image/*');

                input.onchange = function () {
                    var file = this.files[0];

                    var reader = new FileReader();
                    reader.readAsDataURL(file);
                    reader.onload = function () {
                        var id = 'blobid' + (new Date()).getTime();
                        var blobCache = tinymce.activeEditor.editorUpload.blobCache;
                        var base64 = reader.result.split(',')[1];
                        var blobInfo = blobCache.create(id, file, base64);
                        blobCache.add(blobInfo);
                        cb(blobInfo.blobUri(), { title: file.name });
                    };
                };
                input.click();
            }

Controller :

[HttpPost]
public async Task<string> uploadImg(IFormFile imgfile)
{
    string message;
    var saveimg = Path.Combine(webhost.WebRootPath, "Images", imgfile.FileName);
    string imgext = Path.GetExtension(imgfile.FileName);

    if (imgext == ".jpg" || imgext == ".png")
    {
        using (var uploadimg = new FileStream(saveimg, FileMode.Create))
        {

            await imgfile.CopyToAsync(uploadimg);
            message = "The selected file" + imgfile.FileName + " is save";
        }

    }
    else
    {
        message = "only JPG and PNG extensions are supported";
    }
    return "filename : " + saveimg + " message :" + message;
}

Answer 1

Change imgfile to file

public async Task<string> uploadImg(IFormFile file)
{

    //....

}