Is it able to upload a folder with blazor wasm client and minimal api server?

Question

I want to upload files and folders recursively throught the wasm client to minimal api server.

I have learned that I can use IFormFile or IFormFileCollection to receive files in minimal api.

Answer 1

see min api parameter binding for binding to file uploads:

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis/parameter-binding?view=aspnetcore-8.0

the browser only supports multiple file selects for upload, not folders.

Answer 2

Below is a sample of Blazor Web Assembly (WASM) app which can upload file by using jQuery ajax (I don't know what you mean by "recursively" though):

Razor page for file upload

@page "/fileupload"
@inject IJSRuntime JSRuntime;
 
<h3>File Upload by jQuery Ajax</h3>
 
<form id="form1" method="post" enctype="multipart/form-data">
    <input type="file" name="postedfile" />
</form>
 
<button type="button" class="btn btn-primary" @onclick="UploadFile">
    Upload
</button>
 
<div id="result"></div>
 
@code {
    private async Task UploadFile()
    {
        await JSRuntime.InvokeVoidAsync("uploadFile");
    }
}

exampleJsInterop.js

window.uploadFile = () => {
    var fd = new FormData(document.getElementById("form1"));
 
    $.ajax({
        url: '/Upload',
        method: 'post',
        data: fd,
        processData: false,
        contentType: false
    }).done(function (response) {
        $("#result").empty;
        $("#result").text(response);
    }).fail(function (jqXHR, textStatus, errorThrown) {
        $("#result").empty;
        $("#result").text('textStatus: ' + textStatus +
            ', errorThrown: ' + errorThrown);
    });
}

Add jQuery.js and exampleJsInterop.js

Add script tag to index.html

Add controller to Sever project to recive uploaded file

using Microsoft.AspNetCore.Mvc;
 
namespace BlazorWasmCoreHosted.Server.Controllers
{
    [Route("[controller]")]
    [ApiController]
    public class UploadController : ControllerBase
    {
        [HttpPost]
        public string Post([FromForm] IFormFile? postedFile)
        {
            string result = "";
            if (postedFile != null && postedFile.Length > 0)
            {
                string filename = System.IO.Path.GetFileName(postedFile.FileName);
 
                // process of uploaded file - Omitted
 
                result = $"{filename} ({postedFile.ContentType}) - " +
                    $"{postedFile.Length} bytes Upload Complete";
            }
            else
            {
                result = "Upload fail";
            }
 
            return result;
        }
    }
}