使用实体框架和ASP.NET MVC5更新记录

Question

我正在使用以下功能来编辑员工记录。

public async Task<ActionResult> Edit([Bind(Include = "Id,EmployeeId,Name,FatherName,JoiningDate,EndDate,InitialSalary,CurrentSalary,CurrentAddress,PermanentAddress,ContactNumber,EmailId,Gender,DOB,DeptId,DigId,PFNo,BranchCode,Qualification")] Employee employee)
{
        if (ModelState.IsValid)
        {
            string fileName = null;

            if (Request.Files["ImageFileToUpload"]!=null)
            {
                ///Saving the file to EmployeeImages folder with unique name.
                HttpPostedFileBase file = Request.Files["ImageFileToUpload"];
                fileName = UploadEmployeeImage(file);
            }
            else
            {
                ///what condition I need to write here so that if no image selected then it will not update the image field? 
                ///if I am writing       
                fileName = db.Employees.Find(employee.Id).PhotoPath;
                ///it’s showing error.            
            }

            employee.PhotoPath = fileName;

            db.Entry(employee).State = EntityState.Modified;
            await db.SaveChangesAsync();
            return RedirectToAction("Index");
        }

        ViewBag.DeptId = new SelectList(db.Departments, "DeptId", "DeptName", employee.DeptId);
        ViewBag.DigId = new SelectList(db.Designations, "DegId", "DegName", employee.DigId);
        ViewBag.BranchCode = new SelectList(db.Branches, "BranchId", "BranchName", employee.BranchCode);

        return View(employee);
}

选择图像时，我想更新图像字段，否则不应更改员工图像，但其他记录可能会更改。

请在我的代码中建议我需要更新的内容。

Answer 1

终于我得到了我问题的解决方案。 以下代码我用来解决我的问题。

 [HttpPost]
    [ValidateAntiForgeryToken]
    [ActionName("Edit")]
    public async Task<ActionResult> Edit_Post(int Id)
    {
        Employee employee = new Employee();
        employee = db.Employees.FindAsync(Id).Result;
        //if (ModelState.IsValid)
        //{
        string fileName = null;
        if (Request.Files["ImageFileToUpload"].ContentLength >0)
        {
            var file = Request.Files["ImageFileToUpload"];
            ///Saving the file to EmployeeImages folder with unique name.
            if (!string.IsNullOrEmpty(employee.PhotoPath))
            {
                DeleteEmployeeImage(employee.PhotoPath);                    
            }
            fileName = UploadEmployeeImage(file);
            TryUpdateModel(employee);
            employee.PhotoPath = fileName;
        }
        else
        {
            TryUpdateModel(employee, null, null, new string[] { "PhotoPath" });
        }
        if (employee.DigId <= 0)
        {
            ModelState.AddModelError("DigId", "Designation is required");
        }
        if (ModelState.IsValid)
        {
            db.Entry(employee).State = EntityState.Modified;
            await db.SaveChangesAsync();
            return RedirectToAction("Index");
        }

        ViewBag.DeptIdList = new SelectList(db.Departments, "DeptId", "DeptName", employee.DeptId);
        ViewBag.DigIdList = new SelectList(db.Designations, "DegId", "DegName", employee.DigId);
        ViewBag.BranchCodeList = new SelectList(db.Branches, "BranchId", "BranchName", employee.BranchCode);
        return View(employee);
    }

Answer 2

选择图像后可以设置路径。

     if (Request.Files["ImageFileToUpload"]!=null)
        {
            ///Saving the file to EmployeeImages folder with unique name.
            HttpPostedFileBase file = Request.Files["ImageFileToUpload"];
            fileName = UploadEmployeeImage(file);


           employee.PhotoPath = !string.isNullOrWhiteSpace(fileName) ? fileName : employee.PhotoPath ;


        }
        //else
        //{
         // else part not required.       
        //}
          db.Entry(employee).State = EntityState.Modified;
           await db.SaveChangesAsync();