حال برای استفاده از Context تولید شده، به صورت زیر شیءایی را ساخته:

 static DbContext _dbContext=null;
        public static DbContext GetDbContextInstance()
        {
            if (_dbContext == null)
            {
                string path = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location);
                var dllversionAssm = Assembly.LoadFile(path + "\\ProjectContext.dll");
                Type type = dllversionAssm.GetType("DbContextGenerator.TestContext");
                _dbContext = (DbContext)Activator.CreateInstance(type);
            }
            return _dbContext;
        }

و سپس برای ساخت DbSet از هر Entity به کد زیر نیاز خواهیم داشت:

public static System.Data.Entity.DbSet<T> Get<T>() where T : class
        {
            var set = GetDbContextInstance().Set<T>();
            return set;
        }

هم اکنون می‌توان رکوردهای Entity‌ها را واکشی کرده و یا آن‌ها را با یکدیگر Join بزنیم:

            var products = Get<Product>().ToList();

            var productTypes = Get<ProductType>().ToList();


            var query = from p in Get<Product>()
                        join pt in Get<ProductType>() on p.ProductTypeId equals pt.Id
                        select new
                        {
                            Id = p.Id,
                            Name = p.Name,
                            ProductType = pt.Name

                        };

            var JoinResult = query.ToList();

و نتیجه واکشی ها 

کد کامل این پروژه  

 >ng g m UploadFile -m app.module --routing

 >ng g c UploadFile/UploadFileSimple

 >ng g cl UploadFile/Ticket

export class Ticket {
  constructor(public description: string = "") {}
}

import { Ticket } from "./../ticket";

export class UploadFileSimpleComponent implements OnInit {
  model = new Ticket();

<div class="container">
  <h3>Support Form</h3>
  <form #form="ngForm" (submit)="submitForm(form)" novalidate>
    <div class="form-group" [class.has-error]="description.invalid && description.touched">
      <label class="control-label">Description</label>
      <input #description="ngModel" required type="text" class="form-control"
        name="description" [(ngModel)]="model.description">
      <div *ngIf="description.invalid && description.touched">
        <div class="alert alert-danger"  *ngIf="description.errors.required">
          description is required.
        </div>
      </div>
    </div>

    <div class="form-group">
      <label class="control-label">Screenshot(s)</label>
      <input #screenshotInput required type="file" multiple (change)="fileChange($event)"
        class="form-control" name="screenshot">
    </div>

    <button class="btn btn-primary" [disabled]="form.invalid" type="submit">Ok</button>
  </form>
</div>

 (change)="fileChange($event)"

fileChange(event) {
    const filesList: FileList = event.target.files;
    console.log("fileChange() -> filesList", filesList);
}

 C:\Program Files (x86)\Microsoft VS Code\resources\app\extensions\node_modules\typescript\lib\lib.dom.d.ts

{
    "lib": [
      "es2016",
      "dom"
    ]
  }
}

import { Component, OnInit, ViewChild, ElementRef } from "@angular/core";

export class UploadFileSimpleComponent implements OnInit {
  @ViewChild("screenshotInput") screenshotInput: ElementRef;

  submitForm(form: NgForm) {
    const fileInput: HTMLInputElement = this.screenshotInput.nativeElement;
    console.log("fileInput.files", fileInput.files);
  }

 >ng g s UploadFile/UploadFileSimple -m upload-file.module

import { Http, RequestOptions, Response, Headers } from "@angular/http";
import { Injectable } from "@angular/core";
import { Observable } from "rxjs/Observable";
import "rxjs/add/operator/do";
import "rxjs/add/operator/catch";
import "rxjs/add/observable/throw";
import "rxjs/add/operator/map";
import "rxjs/add/observable/of";

import { Ticket } from "./ticket";

@Injectable()
export class UploadFileSimpleService {
  private baseUrl = "api/SimpleUpload";

  constructor(private http: Http) {}

  private extractData(res: Response) {
    const body = res.json();
    return body || {};
  }

  private handleError(error: Response): Observable<any> {
    console.error("observable error: ", error);
    return Observable.throw(error.statusText);
  }

  postTicket(ticket: Ticket, filesList: FileList): Observable<any> {
    if (!filesList || filesList.length === 0) {
      return Observable.throw("Please select a file.");
    }

    const formData: FormData = new FormData();

    for (const key in ticket) {
      if (ticket.hasOwnProperty(key)) {
        formData.append(key, ticket[key]);
      }
    }

    for (let i = 0; i < filesList.length; i++) {
      formData.append(filesList[i].name, filesList[i]);
    }

    const headers = new Headers();
    headers.append("Accept", "application/json");
    const options = new RequestOptions({ headers: headers });

    return this.http
      .post(`${this.baseUrl}/SaveTicket`, formData, options)
      .map(this.extractData)
      .catch(this.handleError);
  }
}

  postTicket(ticket: Ticket, filesList: FileList): Observable<any> {
    const formData: FormData = new FormData();

    for (const key in ticket) {
      if (ticket.hasOwnProperty(key)) {
        formData.append(key, ticket[key]);
      }
    }

    for (let i = 0; i < filesList.length; i++) {
      formData.append(filesList[i].name, filesList[i]);
    }

    const headers = new Headers();
    headers.append("Accept", "application/json");
    const options = new RequestOptions({ headers: headers });

    return this.http
      .post(`${this.baseUrl}/SaveTicket`, formData, options)
      .map(this.extractData)
      .catch(this.handleError);

import { UploadFileSimpleService } from "./../upload-file-simple.service";

export class UploadFileSimpleComponent implements OnInit {
  constructor(private uploadService: UploadFileSimpleService  ) {}

  submitForm(form: NgForm) {
    const fileInput: HTMLInputElement = this.screenshotInput.nativeElement;
    console.log("fileInput.files", fileInput.files);

    this.uploadService
      .postTicket(this.model, fileInput.files)
      .subscribe(data => {
        console.log("success: ", data);
      });
  }

namespace AngularTemplateDrivenFormsLab.Models
{
    public class Ticket
    {
        public int Id { set; get; }
        public string Description { set; get; }
    }
}

using System.IO;
using System.Threading.Tasks;
using AngularTemplateDrivenFormsLab.Models;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;

namespace AngularTemplateDrivenFormsLab.Controllers
{
    [Route("api/[controller]")]
    public class SimpleUploadController : Controller
    {
        private readonly IHostingEnvironment _environment;
        public SimpleUploadController(IHostingEnvironment environment)
        {
            _environment = environment;
        }

        [HttpPost("[action]")]
        public async Task<IActionResult> SaveTicket(Ticket ticket)
        {
            //TODO: save the ticket ... get id
            ticket.Id = 1001;

            var uploadsRootFolder = Path.Combine(_environment.WebRootPath, "uploads");
            if (!Directory.Exists(uploadsRootFolder))
            {
                Directory.CreateDirectory(uploadsRootFolder);
            }

            var files = Request.Form.Files;
            foreach (var file in files)
            {
                //TODO: do security checks ...!

                if (file == null || file.Length == 0)
                {
                    continue;
                }

                var filePath = Path.Combine(uploadsRootFolder, file.FileName);
                using (var fileStream = new FileStream(filePath, FileMode.Create))
                {
                    await file.CopyToAsync(fileStream).ConfigureAwait(false);
                }
            }

            return Created("", ticket);
        }
    }
}

 SaveTicket(Ticket ticket)

 formData.append(filesList[i].name, filesList[i]);

var files = Request.Form.Files;
foreach (var file in files)

<div class="form-group">
    <InputFile OnChange="HandleImageUpload" multiple></InputFile>
</div>

@code
{
    private async Task HandleImageUpload(InputFileChangeEventArgs args)
    {

    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;

namespace BlazorServer.Models
{
    public class HotelRoomDTO
    {
        // ... 
        public virtual ICollection<HotelRoomImageDTO> HotelRoomImages { get; set; } = new List<HotelRoomImageDTO>();
    }
}

@inject IHotelRoomService HotelRoomService
@inject NavigationManager NavigationManager
@inject IJSRuntime JsRuntime
@inject IFileUploadService FileUploadService
@inject IWebHostEnvironment WebHostEnvironment

@code
{
    // ...

    private async Task HandleImageUpload(InputFileChangeEventArgs args)
    {
        var files = args.GetMultipleFiles(maximumFileCount: 5);
        if (args.FileCount == 0 || files.Count == 0)
        {
            return;
        }

        var allowedExtensions = new List<string> { ".jpg", ".png", ".jpeg" };
        if(!files.Any(file => allowedExtensions.Contains(Path.GetExtension(file.Name), StringComparer.OrdinalIgnoreCase)))
        {
            await JsRuntime.ToastrError("Please select .jpg/.jpeg/.png files only.");
            return;
        }

        foreach (var file in files)
        {
            var uploadedImageUrl = await FileUploadService.UploadFileAsync(file, WebHostEnvironment.WebRootPath, "Uploads");
            HotelRoomModel.HotelRoomImages.Add(new HotelRoomImageDTO { RoomImageUrl = uploadedImageUrl });
        }
    }
}

@using Microsoft.AspNetCore.Hosting
@using System.Linq
@using System.IO

.room-image {
  display: block;
  width: 100%;
  height: 150px;
  background-size: cover !important;
  border: 3px solid green;
  position: relative;
}

.room-image-title {
  position: absolute;
  top: 0;
  right: 0;
  background-color: green;
  color: white;
  padding: 0px 6px;
  display: inline-block;
}

<div class="form-group">
    <InputFile OnChange="HandleImageUpload" multiple></InputFile>
    <div class="row">
    @if (HotelRoomModel.HotelRoomImages.Count > 0)
    {
        var serial = 1;
        foreach (var roomImage in HotelRoomModel.HotelRoomImages)
        {
            <div class="col-md-2 mt-3">
                <div class="room-image" style="background: url('@roomImage.RoomImageUrl') 50% 50%; ">
                   <span class="room-image-title">@serial</span>
                </div>
                <button type="button" class="btn btn-outline-danger btn-block mt-4">Delete</button>
            </div>
            serial++;
        }
    }
    </div>
</div>

// ...
@inject IHotelRoomImageService HotelRoomImageService


@code
{
    // ...

    private async Task AddHotelRoomImageAsync(HotelRoomDTO roomDto)
    {
        foreach (var imageDto in HotelRoomModel.HotelRoomImages)
        {
            imageDto.RoomId = roomDto.Id;
            await HotelRoomImageService.CreateHotelRoomImageAsync(imageDto);
        }
    }
}

HotelRoomModel.HotelRoomImages.Add(new HotelRoomImageDTO { RoomImageUrl = uploadedImageUrl });

private async Task HandleHotelRoomUpsert()
    {
       // ...

       // Create Mode
       var createdRoomDto = await HotelRoomService.CreateHotelRoomAsync(HotelRoomModel);
       await AddHotelRoomImageAsync(createdRoomDto);
       await JsRuntime.ToastrSuccess($"The `{HotelRoomModel.Name}` created successfully.");

       // ... 
    }

    protected override async Task OnInitializedAsync()
    {
        if (Id.HasValue)
        {
            // Update Mode
            Title = "Update";
            HotelRoomModel = await HotelRoomService.GetHotelRoomAsync(Id.Value);
        }
        // ...
    }

namespace BlazorServer.Services
{
    public class HotelRoomService : IHotelRoomService
    {
        // ...
 
        public IAsyncEnumerable<HotelRoomDTO> GetAllHotelRoomsAsync()
        {
            return _dbContext.HotelRooms
                        .Include(x => x.HotelRoomImages)
                        .ProjectTo<HotelRoomDTO>(_mapperConfiguration)
                        .AsAsyncEnumerable();
        }

        public Task<HotelRoomDTO> GetHotelRoomAsync(int roomId)
        {
            return _dbContext.HotelRooms
                            .Include(x => x.HotelRoomImages)
                            .ProjectTo<HotelRoomDTO>(_mapperConfiguration)
                            .FirstOrDefaultAsync(x => x.Id == roomId);
        }
    }
}

private async Task HandleHotelRoomUpsert()
{
   //...

   // Update Mode
   var updatedRoomDto = await HotelRoomService.UpdateHotelRoomAsync(HotelRoomModel.Id, HotelRoomModel);
   await AddHotelRoomImageAsync(updatedRoomDto);
   await JsRuntime.ToastrSuccess($"The `{HotelRoomModel.Name}` updated successfully.");

   //...
}

    private async Task AddHotelRoomImageAsync(HotelRoomDTO roomDto)
    {
        foreach (var imageDto in HotelRoomModel.HotelRoomImages.Where(x => x.RoomId == 0))
        {
            imageDto.RoomId = roomDto.Id;
            await HotelRoomImageService.CreateHotelRoomImageAsync(imageDto);
        }
    }

public async Task<HotelRoomDTO> CreateHotelRoomAsync(HotelRoomDTO hotelRoomDTO)
{
   var hotelRoom = _mapper.Map<HotelRoom>(hotelRoomDTO);

filterContext.ActionDescriptor.ControllerDescriptor.ControllerName
filterContext.ActionDescriptor.ActionName

public abstract class AdoMapper<T> where T : class
{
    private readonly SqlConnection _connection;
 
    protected AdoMapper(string connectionString)
    {
        _connection = new SqlConnection(connectionString);
    }
 
    protected virtual IEnumerable<T> ExecuteCommand(SqlCommand command)
    {
        command.Connection = _connection;
        command.CommandType = CommandType.StoredProcedure;
        _connection.Open();
 
        try
        {
            var reader = command.ExecuteReader();
            try
            {
                return Mapper.Map<IDataReader, IEnumerable<T>>(reader);
            }
            finally
            {
                reader.Close();
            }
        }
        finally
        {
            _connection.Close();
        }
    }
 
    protected virtual T GetRecord(SqlCommand command)
    {
        command.Connection = _connection;
        _connection.Open();
        try
        {
            var reader = command.ExecuteReader();
            try
            {
                reader.Read();
                return Mapper.Map<IDataReader, T>(reader);
            }
            finally
            {
                reader.Close();
            }
        }
        finally
        {
            _connection.Close();
        }
    }
 
    protected virtual IEnumerable<T> GetRecords(SqlCommand command)
    {
        command.Connection = _connection;
        _connection.Open();
        try
        {
            var reader = command.ExecuteReader();
            try
            {
                return Mapper.Map<IDataReader, IEnumerable<T>>(reader);
            }
            finally
            {
                reader.Close();
            }
        }
        finally
        {
            _connection.Close();
        }
    }
}

public class UsersService : AdoMapper<User>, IUsersService
{
    public UsersService(string connectionString)
        : base(connectionString)
    {
    }
 
    public IEnumerable<User> GetAll()
    {
        using (var command = new SqlCommand("SELECT * FROM Users"))
        {
            return GetRecords(command);
        }
    }
 
    public User GetById(int id)
    {
        using (var command = new SqlCommand("SELECT * FROM Users WHERE Id = @id"))
        {
            command.Parameters.Add(new SqlParameter("id", id));
            return GetRecord(command);
        }
    }
}

public class UsersProfile : Profile
{
    protected override void Configure()
    {
        this.CreateMap<IDataRecord, User>();
    }
 
    public override string ProfileName
    {
        get { return this.GetType().Name; }
    }
}

Mapper.Initialize(cfg => // In Application_Start()
{
    cfg.AddProfile<UsersProfile>();
});

public class Advertisement
{
    public int Id { set; get; }
    public string Title { get; set; }
    public string Description { get; set; }
    public int UserId { get; set; }
 
    public string TitleWithOtherName { get; set; }
}

public class AdvertisementsProfile : Profile
{
    protected override void Configure()
    {
        this.CreateMap<IDataRecord, Advertisement>()
            .ForMember(dest => dest.TitleWithOtherName,
                       options => options.MapFrom(src =>
                            src.GetString(src.GetOrdinal("Title"))));
    }
 
    public override string ProfileName
    {
        get { return this.GetType().Name; }
    }
}

[HttpPost]
        public ActionResult Edit(User user, string[] tags)
        {
            if (ModelState.IsValid)
            {
                List<Role> roles = new List<Role>();
                foreach (var item in tags)
                {
                    Role role = db.Roles.Find(long.Parse(item));
                    roles.Add(role);
                }
                user.Roles = roles;
                
                db.Entry(user).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            return View(user);
        }

using System.ComponentModel.DataAnnotations;

namespace BlazorWasmUpload.Shared
{
    public class User
    {
        [Required]
        public string Name { get; set; }

        [Required]
        [Range(18, 90)]
        public int Age { get; set; }
    }
}

namespace BlazorWasmUpload.Server.Controllers
{
    [ApiController]
    [Route("api/[controller]/[action]")]
    public class FilesController : ControllerBase
    {
        [HttpPost]
        public async Task<IActionResult> CreateUser(
            [FromForm] User userModel,
            [FromForm] IList<IFormFile> inputFiles = null)

using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Components.Forms;

namespace BlazorWasmUpload.Client.Services
{
    public interface IFilesManagerService
    {
        Task<HttpResponseMessage> PostModelWithFilesAsync<T>(string requestUri,
            IEnumerable<IBrowserFile> browserFiles,
            string fileParameterName,
            T model,
            string modelParameterName);
    }

    public class FilesManagerService : IFilesManagerService
    {
        private readonly HttpClient _httpClient;

        public FilesManagerService(HttpClient httpClient)
        {
            _httpClient = httpClient;
        }

        public async Task<HttpResponseMessage> PostModelWithFilesAsync<T>(
            string requestUri,
            IEnumerable<IBrowserFile> browserFiles,
            string fileParameterName,
            T model,
            string modelParameterName)
        {
            var requestContent = new MultipartFormDataContent();
            requestContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data");

            if (browserFiles?.Any() == true)
            {
                foreach (var file in browserFiles)
                {
                    var stream = file.OpenReadStream(maxAllowedSize: 512000 * 1000);
                    requestContent.Add(content: new StreamContent(stream, (int)file.Size), name: fileParameterName, fileName: file.Name);
                }
            }

            requestContent.Add(
                content: new StringContent(JsonSerializer.Serialize(model), Encoding.UTF8, "application/json"),
                name: modelParameterName);

            var result = await _httpClient.PostAsync(requestUri, requestContent);
            result.EnsureSuccessStatusCode();
            return result;
        }
    }
}

namespace BlazorWasmUpload.Client
{
    public class Program
    {
        public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);
            // ...

            builder.Services.AddScoped<IFilesManagerService, FilesManagerService>();

            // ...
        }
    }
}

@code
{
    IReadOnlyList<IBrowserFile> SelectedFiles;
    User UserModel = new User();
    bool isProcessing;
    string UploadErrorMessage;

@page "/"

@using System.IO
@using BlazorWasmUpload.Shared
@using BlazorWasmUpload.Client.Services

@inject IFilesManagerService FilesManagerService

<h3>Post a model with files</h3>

<EditForm Model="UserModel" OnValidSubmit="CreateUserAsync">
    <DataAnnotationsValidator />
    <div>
        <label>Name</label>
        <InputText @bind-Value="UserModel.Name"></InputText>
        <ValidationMessage For="()=>UserModel.Name"></ValidationMessage>
    </div>
    <div>
        <label>Age</label>
        <InputNumber @bind-Value="UserModel.Age"></InputNumber>
        <ValidationMessage For="()=>UserModel.Age"></ValidationMessage>
    </div>
    <div>
        <label>Photos</label>
        <InputFile multiple disabled="@isProcessing" OnChange="OnInputFileChange" />
        @if (!string.IsNullOrWhiteSpace(UploadErrorMessage))
        {
            <div>
                @UploadErrorMessage
            </div>
        }
        @if (SelectedFiles?.Count > 0)
        {
            <table>
                <thead>
                    <tr>
                        <th>Name</th>
                        <th>Size (bytes)</th>
                        <th>Last Modified</th>
                        <th>Type</th>
                    </tr>
                </thead>
                <tbody>
                    @foreach (var selectedFile in SelectedFiles)
                    {
                        <tr>
                            <td>@selectedFile.Name</td>
                            <td>@selectedFile.Size</td>
                            <td>@selectedFile.LastModified</td>
                            <td>@selectedFile.ContentType</td>
                        </tr>
                    }
                </tbody>
            </table>
        }
    </div>
    <div>
        <button disabled="@isProcessing">Create user</button>
    </div>
</EditForm>

    private void OnInputFileChange(InputFileChangeEventArgs args)
    {
        var files = args.GetMultipleFiles(maximumFileCount: 15);
        if (args.FileCount == 0 || files.Count == 0)
        {
            UploadErrorMessage = "Please select a file.";
            return;
        }

        var allowedExtensions = new List<string> { ".jpg", ".png", ".jpeg" };
        if(!files.Any(file => allowedExtensions.Contains(Path.GetExtension(file.Name), StringComparer.OrdinalIgnoreCase)))
        {
            UploadErrorMessage = "Please select .jpg/.jpeg/.png files only.";
            return;
        }

        SelectedFiles = files;
        UploadErrorMessage = string.Empty;
    }

    private async Task CreateUserAsync()
    {
        try
        {
            isProcessing = true;
            await FilesManagerService.PostModelWithFilesAsync(
                        requestUri: "api/Files/CreateUser",
                        browserFiles: SelectedFiles,
                        fileParameterName: "inputFiles",
                        model: UserModel,
                        modelParameterName: "userModel");
            UserModel = new User();
        }
        finally
        {
            isProcessing = false;
            SelectedFiles = null;
        }
    }

using System.IO;
using Microsoft.AspNetCore.Mvc;
using BlazorWasmUpload.Shared;
using Microsoft.AspNetCore.Hosting;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using System.Collections.Generic;
using Microsoft.Extensions.Logging;
using System.Text.Json;
using BlazorWasmUpload.Server.Utils;
using System.Linq;

namespace BlazorWasmUpload.Server.Controllers
{
    [ApiController]
    [Route("api/[controller]/[action]")]
    public class FilesController : ControllerBase
    {
        private const int MaxBufferSize = 0x10000;

        private readonly IWebHostEnvironment _webHostEnvironment;
        private readonly ILogger<FilesController> _logger;

        public FilesController(
            IWebHostEnvironment webHostEnvironment,
            ILogger<FilesController> logger)
        {
            _webHostEnvironment = webHostEnvironment;
            _logger = logger;
        }

        [HttpPost]
        public async Task<IActionResult> CreateUser(
            //[FromForm] string userModel, // <-- this is the actual form of the posted model
            [ModelBinder(BinderType = typeof(JsonModelBinder)), FromForm] User userModel,
            [FromForm] IList<IFormFile> inputFiles = null)
        {
            /*var user = JsonSerializer.Deserialize<User>(userModel);
            _logger.LogInformation($"userModel.Name: {user.Name}");
            _logger.LogInformation($"userModel.Age: {user.Age}");*/

            _logger.LogInformation($"userModel.Name: {userModel.Name}");
            _logger.LogInformation($"userModel.Age: {userModel.Age}");

            var uploadsRootFolder = Path.Combine(_webHostEnvironment.WebRootPath, "Files");
            if (!Directory.Exists(uploadsRootFolder))
            {
                Directory.CreateDirectory(uploadsRootFolder);
            }

            if (inputFiles?.Any() == true)
            {
                foreach (var file in inputFiles)
                {
                    if (file == null || file.Length == 0)
                    {
                        continue;
                    }

                    var filePath = Path.Combine(uploadsRootFolder, file.FileName);
                    using var fileStream = new FileStream(filePath,
                                                            FileMode.Create,
                                                            FileAccess.Write,
                                                            FileShare.None,
                                                            MaxBufferSize,
                                                            useAsync: true);
                    await file.CopyToAsync(fileStream);
                    _logger.LogInformation($"Saved file: {filePath}");
                }
            }

            return Ok();
        }
    }
}

[ModelBinder(BinderType = typeof(JsonModelBinder)), FromForm] User userModel,

using System;
using System.Text.Json;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc.ModelBinding;

namespace BlazorWasmUpload.Server.Utils
{
    public class JsonModelBinder : IModelBinder
    {
        public Task BindModelAsync(ModelBindingContext bindingContext)
        {
            if (bindingContext == null)
            {
                throw new ArgumentNullException(nameof(bindingContext));
            }

            var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
            if (valueProviderResult != ValueProviderResult.None)
            {
                bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueProviderResult);

                var valueAsString = valueProviderResult.FirstValue;
                var result = JsonSerializer.Deserialize(valueAsString, bindingContext.ModelType);
                if (result != null)
                {
                    bindingContext.Result = ModelBindingResult.Success(result);
                    return Task.CompletedTask;
                }
            }

            return Task.CompletedTask;
        }
    }
}

[HttpPost]
public async Task<IActionResult> CreateUser(
            [FromForm] string userModel, // <-- this is the actual form of the posted model
            [FromForm] IList<IFormFile> inputFiles = null)
{
  var user = JsonSerializer.Deserialize<User>(userModel);