Error System.NullReferenceException: Object reference not set to an instance of an object

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I want to read excel file and save it into dataset then put into database.
The code is work fine when debugging, means I can upload the file,read it and save into database.
But after I publish the project.
It show me error System.NullReferenceException: Object reference not set to an instance of an object.

C#

string path = System.IO.Path.GetFullPath(vault + "/" + FileUpload1.FileName);
         DataSet ds = new DataSet();
         ds = sctt.utility.GetValue.ReadExcelFile(path, "SELECT * FROM [Sheet1$]");
         string statusid = UCA.Common.Utility.GetValue.getSQLValue("SELECT TOP (1) Asset_Status_ID FROM Asset_Status WHERE (Name = 'Available')");
         if (ds.Tables[0].Rows.Count > 0)

The error message is at this line if (ds.Tables[0].Rows.Count > 0)

Posted 15-Dec-13 22:32pm

hueikar

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hueikar 17-Dec-13 2:32am

Hi, I had solve the problem using another method : TextFieldParser. Thnx for all reply.

3 solutions

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Richard MacCutchan · Answer 1 · 2013-12-15T22:38:00

Solution 1

That probably means that either the method sctt.utility.GetValue.ReadExcelFile returned null, or you have not read any tables into your DataSet. Take a look at Working with MS Excel(xls / xlsx) Using MDAC and Oledb[^] for information on reading Excel files in .NET.

Posted 15-Dec-13 22:38pm

Richard MacCutchan

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BillWoodruff 16-Dec-13 4:46am

Any time I post a response, and, then, find I composed the response while Richard MacCutchan was composing his, and then find our responses were ... in general ... along the same lines: I feel both humbled ... and that there is some hope for me, technically :)

Richard MacCutchan 16-Dec-13 4:49am

Strange, I feel exactly the same when I see your answers.

hueikar 16-Dec-13 8:46am

Hi, Yup. I try put (if dataset is null then label will show it)
So how can i debug it? Because it works well when I upload excel file in debug mode.
Then after I publish the system then its not working.

Richard MacCutchan 16-Dec-13 9:26am

You need to add some more code to list out the items tha may be causing the failure. There are quite a few varibles in the code, so any one of them could be the root cause. Take a look at this CodeProject article for useful guidance on logging information from your release version.

BillWoodruff · Answer 2 · 2013-12-15T22:43:00

I think there's a high probability that the code in the call to a method of the "sctt" return null. Why not check that by wrapping the code in something like:

C#

ds = sctt.utility.GetValue.ReadExcelFile(path, "SELECT * FROM [Sheet1$]");
// check for null dataset
if (ds == null)
{
     MessageBox.Show("ds is null);
     
     // code to abort ... or whatever
{
else
{
     string statusid = UCA.Common.Utility.GetValue.getSQLValue("SELECT TOP (1) Asset_Status_ID FROM Asset_Status WHERE (Name = 'Available')");
     if (ds.Tables[0].Rows.Count > 0) // ?
}

Or, use a try/catch/finally block.

Gaurav Makwana · Answer 3 · 2013-12-16T17:49:00

Solution 4

dont do anything just write your code in try catch and see some value is getting null value

think and do bro it will solve automatically just try!

Posted 16-Dec-13 17:49pm

Gaurav Makwana

Comments

Ron Beyer 16-Dec-13 23:52pm

Exceptions don't get solved automatically just because you put them in try/catch blocks, it just suppresses the exception message if you are not handling it correctly.

Gaurav Makwana 17-Dec-13 3:19am

before automatically i wrote think and do its not big bug or error for the beginner also so plz just think and do

Error System.NullReferenceException: Object reference not set to an instance of an object

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