If ienumerable<httppostedfilebase> passing null error.

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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:

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.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...

Posted 8-Mar-17 4:08am

Rajesh Kumar 2013

Updated 8-Mar-17 5:30am

v2

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Comments

Richard MacCutchan 8-Mar-17 11:28am

Just check if the variable is null before you try to use it.

Member 12955507 8-Mar-17 11:32am

Yes, sir variable is null. Because, from 3 file uploader I will use only one or two even all. If I am not using one then how can I manage the code? Please help me

Richard MacCutchan 8-Mar-17 11:42am

Are you saying that you do not know how to write an if (variable == null) statement?

Rajesh Kumar 2013 8-Mar-17 20:48pm

yes! sir, I did write if (List[i] != null) now it working fine. Thank you.

Richard Deeming 9-Mar-17 11:29am

IList<HttpPostedFileBase> list = (IList<HttpPostedFileBase>)fileUpload;

If you want the argument type to be IList<HttpPostedFileBase>, then declare it as such.

As it stands, your method could accept anything that implements IEnumerable<HttpPostedFileBase>, even if it doesn't also implement IList<HttpPostedFileBase>, and your hidden requirement would lead to a runtime exception.

Rajesh Kumar 2013 10-Mar-17 1:20am

sure. thanks sir. I am also converting like that, IList<httppostedfilebase> list = (IList<httppostedfilebase>)fileUpload; Is it safe mode?

Richard Deeming 10-Mar-17 7:29am

The problem is that you're declaring that your method can accept anything that implements IEnumerable<HttpPostedFileBase>, but you're then going to throw an exception at runtime if the parameter doesn't also implement IList<HttpPostedFileBase>. Hidden requirements for your parameters are always a bad idea.

If you declare the parameter as IList<HttpPostedFileBase> instead, the requirement becomes obvious. If you try to call the method with something that doesn't match the requirement, you'll get a compiler error telling you what you need to fix, rather than having your code fail at runtime.

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Karthik_Mahalingam · Accepted Answer · 2017-03-08T05:30:00

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);
                    }
                }
            }