public async Task <IActionResult> AddFile()
        {
            string solutionFileLoadPath = _environment.WebRootPath + "\\Files\\" + "\\SolutionFiles\\";
            var    detail = new OperationDetailDTO();

            try
            {
                var allForms = Request.Form;

                StringValues solutionIdString;
                var          solIdRes   = allForms.TryGetValue(allForms.Keys.First(), out solutionIdString);
                var          strId      = solutionIdString.ToString();
                var          solutionID = Convert.ToInt32(strId);

                var file = Request.Form.Files[0];
                if (file != null)
                {
                    string             userFileName   = file.FileName;
                    string             uniqueFileName = System.Guid.NewGuid() + userFileName;
                    OperationDetailDTO fileRes        = new OperationDetailDTO();

                    var currentFileRes = await _taskService.GetSolutionFileNameAsync(solutionID);

                    if (currentFileRes.Succeeded)
                    {
                        using (var fileStream = System.IO.File.Create(solutionFileLoadPath + uniqueFileName))
                        {
                            file.CopyTo(fileStream);
                        }

                        if (System.IO.File.Exists(_environment.WebRootPath + currentFileRes.filePath))
                        {
                            System.IO.File.Delete(_environment.WebRootPath + currentFileRes.filePath);
                        }

                        fileRes = await _taskService.UpdateSolutionFileAsync(currentFileRes.fileId, userFileName, uniqueFileName);
                    }

                    else
                    {
                        using (var fileStream = System.IO.File.Create(solutionFileLoadPath + uniqueFileName))
                        {
                            file.CopyTo(fileStream);
                        }

                        fileRes = await _taskService.AddFileToSolutionAsync(solutionID, userFileName, uniqueFileName);
                    }

                    if (!fileRes.Succeeded)
                    {
                        if (System.IO.File.Exists(solutionFileLoadPath + uniqueFileName))
                        {
                            System.IO.File.Delete(solutionFileLoadPath + uniqueFileName);
                        }

                        detail.ErrorMessages.Add("Не удалось загрузить файл к решению задачи.");
                        detail.ErrorMessages.AddRange(fileRes.ErrorMessages);
                    }
                    else
                    {
                        detail.Succeeded = true;
                    }
                }
                else
                {
                    detail.ErrorMessages.Add("Файл равен null");
                }
                return(Ok(detail));
            }
            catch (Exception e)
            {
                detail.ErrorMessages.Add("Ошибка на сервере при загрузке файлов: " + e.Message);
                return(Ok(detail));
            }
        }