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System.NullReferenceException when checking Count of DataTable rows

dba123
dba123 asked
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Last Modified: 2010-07-27
Why do I get object reference error here if I've clearly defined my 2 data tables?

        Dim dtPhones As DataTable = GetInfo(Int32.Parse(syStudentID))
        Dim dtPhonestest As DataTable = GetPhoneList(CInt(Request.QueryString("LeadID")))


        If ((dtPhones.Rows.Count > 0) AndAlso (dtPhonestest.Rows.Count > 0)) Then

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

it's referring to dtPhones.Rows.Count > 0
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Dustin HopkinsSenior Web Developer
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Commented:
From what you've given, it looks to me like the problem lays with the count method. You should try changing the "rows.count > 0" to "rows.count -1 > 0"
The reason is count, counts all the rows in the datagrid...including "0". So you must subtract 1 in order for the numbers to match.
So your code would look like this:
Dim dtPhones As DataTable = GetInfo(Int32.Parse(syStudentID))
        Dim dtPhonestest As DataTable = GetPhoneList(CInt(Request.QueryString("LeadID")))
        If ((dtPhones.Rows.Count - 1 > 0) AndAlso (dtPhonestest.Rows.Count - 1  > 0)) Then

If that doesn't fix it then you should what TSmooth said and debug values.
Dustin HopkinsSenior Web Developer
CERTIFIED EXPERT

Commented:
I'm sorry I misread what you were doing. what I wrote above was for if you were looping through the table. TSmooth is right, you should output the results of those functions to make sure they're outputing what you think they are.

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