如果是ienumerable< httppostedfilebase>传递null错误。 [英] If ienumerable<httppostedfilebase> passing null error.

问题描述

我正在研究mvc 5项目，视图页面内有3个输入类型文件上传器。



这里如果我选择的只有一个fileUploader，另外两个正在传递null。如果null存在，我想避免保存。通过使用下面的代码，我该如何解决这个问题？



错误：对象引用没有设置为对象的实例。



请找到下面的图片，显示错误原因。
[ ^ ]



我的尝试：



< pre lang =c＃> [HttpPost]
public ActionResult PremiumUserRegistration（IEnumerable< HttpPostedFileBase> fileUpload）
{
IList< HttpPostedFileBase> ; list =（IList< HttpPostedFileBase>）fileUpload;
HttpFileCollectionBase files = Request.Files;
var httpPostedFile = HttpContext.Request.Files [ 0 ];

if （httpPostedFile.ContentLength！= 0 ）
{
for （ int i = 0 ; i < fileUpload.C​​ount（）; i ++）
{
if （list [i] .ContentLength > 0 && i == 0 ）
{
HttpPostedFileBase file = files [i];
LogoImage = Path.GetFileName（partnersVM.listPartnerVM.PartnerName + _ + list [ I] .FileName）;
var path = Path.Combine（Server.MapPath（ 〜/ UploadedImages / PremiUserRegistration / LogoImage /），LogoImage）;
file.SaveAs（path）;
}
else if （list [i] .ContentLength > 0 && i == 1 ）
{
HttpPostedFileBase file = files [i];
TitlePictureImage = Path.GetFileName（partnersVM.listPartnerVM.PartnerName + _ + list [ I] .FileName）;
var path = Path.Combine（Server.MapPath（ 〜/ UploadedImages / PremiUserRegistration / TitlePicture /），TitlePictureImage）;
file.SaveAs（path）;
}
else if （list [i] .ContentLength > 0 && i == 2 ）
{
HttpPostedFileBase file = files [i];
TitlePictureImage = Path.GetFileName（partnersVM.listPartnerVM.PartnerName + _ + list [ I] .FileName）;
var path = Path.Combine（Server.MapPath（ 〜/ UploadedImages / PremiUserRegistration / Brochure /），TitlePictureImage）;
file.SaveAs（path）;
}
}
}
}

请帮助我...

解决方案

添加此行以验证 null value

 for（int i = 0; i< fileUpload.C​​ount（）; i ++）
 {
   if（List [i]！= null ）  
 {
 if（list [i] .ContentLength> 0&& i == 0）
 {
 HttpPostedFileBase file =文件[I]; 
 LogoImage = Path.GetFileName（partnersVM.listPartnerVM.PartnerName +_+ list [i] .FileName）; 
 var path = Path.Combine（Server.MapPath（〜/ UploadedImages / PremiUserRegistration / LogoImage /），LogoImage）; 
 file.SaveAs（path）; 
} 
 else if（list [i] .ContentLength> 0&& i == 1）
 {
 HttpPostedFileBase file = files [i]; 
 TitlePictureImage = Path.GetFileName（partnersVM.listPartnerVM.PartnerName +_+ list [i] .FileName）; 
 var path = Path.Combine（Server.MapPath（〜/ UploadedImages / PremiUserRegistration / TitlePicture /），TitlePictureImage）; 
 file.SaveAs（path）; 
} 
 else if（list [i] .ContentLength> 0&& i == 2）
 {
 HttpPostedFileBase file = files [i]; 
 TitlePictureImage = Path.GetFileName（partnersVM.listPartnerVM.PartnerName +_+ list [i] .FileName）; 
 var path = Path.Combine（Server.MapPath（〜/ UploadedImages / PremiUserRegistration / Brochure /），TitlePictureImage）; 
 file.SaveAs（path）; 
} 
} 
} 

I am working on mvc 5 project, there is 3 input type file uploader inside view page.

Here if I am selecting the only one fileUploader, another two are passing null. I want to avoid to save if null existing. By using below code, how can I solve that issue?

error: "Object reference not set to an instance of an object."

please find the below image, that showing error cause.
[^]

What I have tried:

[HttpPost]
 public ActionResult PremiumUserRegistration(IEnumerable<HttpPostedFileBase> fileUpload)
      {
 IList<HttpPostedFileBase> list = (IList<HttpPostedFileBase>)fileUpload;
                HttpFileCollectionBase files = Request.Files;
                var httpPostedFile = HttpContext.Request.Files[0];      

if (httpPostedFile.ContentLength != 0)
                    {
                        for (int i = 0; i < fileUpload.Count(); i++)
                        {
                            if (list[i].ContentLength > 0 && i == 0)
                            {
                                HttpPostedFileBase file = files[i];
                                LogoImage = Path.GetFileName(partnersVM.listPartnerVM.PartnerName + "_" + list[i].FileName);
                                var path = Path.Combine(Server.MapPath("~/UploadedImages/PremiUserRegistration/LogoImage/"), LogoImage);
                                file.SaveAs(path);
                            }
                            else if (list[i].ContentLength > 0 && i == 1)
                            {
                                HttpPostedFileBase file = files[i];
                                TitlePictureImage = Path.GetFileName(partnersVM.listPartnerVM.PartnerName + "_" + list[i].FileName);
                                var path = Path.Combine(Server.MapPath("~/UploadedImages/PremiUserRegistration/TitlePicture/"), TitlePictureImage);
                                file.SaveAs(path);
                            }
                            else if (list[i].ContentLength > 0 && i == 2)
                            {
                                HttpPostedFileBase file = files[i];
                                TitlePictureImage = Path.GetFileName(partnersVM.listPartnerVM.PartnerName + "_" + list[i].FileName);
                                var path = Path.Combine(Server.MapPath("~/UploadedImages/PremiUserRegistration/Brochure/"), TitlePictureImage);
                                file.SaveAs(path);
                            }
                        }
                    }
}

Please help me...

解决方案

add this line to validate null value

for (int i = 0; i < fileUpload.Count(); i++)
            {
                if (List[i] != null)
                {
                    if (list[i].ContentLength > 0 && i == 0)
                    {
                        HttpPostedFileBase file = files[i];
                        LogoImage = Path.GetFileName(partnersVM.listPartnerVM.PartnerName + "_" + list[i].FileName);
                        var path = Path.Combine(Server.MapPath("~/UploadedImages/PremiUserRegistration/LogoImage/"), LogoImage);
                        file.SaveAs(path);
                    }
                    else if (list[i].ContentLength > 0 && i == 1)
                    {
                        HttpPostedFileBase file = files[i];
                        TitlePictureImage = Path.GetFileName(partnersVM.listPartnerVM.PartnerName + "_" + list[i].FileName);
                        var path = Path.Combine(Server.MapPath("~/UploadedImages/PremiUserRegistration/TitlePicture/"), TitlePictureImage);
                        file.SaveAs(path);
                    }
                    else if (list[i].ContentLength > 0 && i == 2)
                    {
                        HttpPostedFileBase file = files[i];
                        TitlePictureImage = Path.GetFileName(partnersVM.listPartnerVM.PartnerName + "_" + list[i].FileName);
                        var path = Path.Combine(Server.MapPath("~/UploadedImages/PremiUserRegistration/Brochure/"), TitlePictureImage);
                        file.SaveAs(path);
                    }
                }
            }

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