Looping through a datareader in .net 1.1 reading the data into an array

[kamran1976]

I am trying to loop through the fields in a datareader so that i can read the data into an array. It works the first time around i.e the first column, but when i=1 a get an "Object reference not set to an instance of an object" error. Please tell me what i am doing wrong!

heres the code:

If rdr.HasRows Then
rdr.Read()
For i = 0 To rdr.FieldCount
arrValues(i) = CStr(rdr.Item(i))
Next
End If

[nateraaaa]

I am trying to loop through the fields in a datareader so that i can read the data into an array. It works the first time around i.e the first column, but when i=1 a get an "Object reference not set to an instance of an object" error. Please tell me what i am doing wrong!

heres the code:

If rdr.HasRows Then
rdr.Read()
For i = 0 To rdr.FieldCount
arrValues(i) = CStr(rdr.Item(i))
Next
End If

You may want to try something like this.

Dim i As Integer = 0
 
While rdr.Read
    arrValues(i) = CStr(rdr.Item(i))
    i = (i + 1)
 
End While

Nathan

[Frinavale]

You may want to try something like this.

Dim i As Integer = 0
 
While rdr.Read
    arrValues(i) = CStr(rdr.Item(i))
    i = (i + 1)
 
End While

Nathan

Nathan's code should work for you but I still recommend putting it within a Try Catch block just in case.

-Frinny

[kamran1976]

That doesnt work - i am still getting the same error. Here is the full code snippet. the datareader should contain 1 row with 35 columns in it:

 
Dim i
Dim rdr As SqlDataReader
Dim cn As New SqlConnection(ConfigurationSettings.AppSettings("sConnectionString"))
cn.Open()
 
Dim cmd As New SqlCommand("SELECT * FROM tblUser WHERE UserID=" & Session("UserID"), cn)
rdr = cmd.ExecuteReader
Dim arrValues() As String
 
If rdr.HasRows Then
rdr.Read()
For i = 0 To rdr.FieldCount
arrValues(i) = CStr(rdr.Item(i))
Next
End If
cn.Close()
For i = LBound(arrValues) To UBound(arrValues)
Response.Write(arrValues(i))
Next

[Frinavale]

Check out this .Net Article on how to use a database in your program....there's an example there on how to retrieve your values.

Try it out and let me know if you still have problems :)

-Frinny

[kamran1976]

it was the array that was causing the problem - i had to resize it for each iteration of the loop. the following code sample now operates as expected:

If rdr.HasRows Then
rdr.Read()
For i = 0 To rdr.FieldCount - 1
ReDim Preserve arrValues(i)
arrValues(i) = CStr(rdr.Item(i))
Next
End If
 

thanks for your help!
Kamran

[Frinavale]

it was the array that was causing the problem - i had to resize it for each iteration of the loop. the following code sample now operates as expected:

If rdr.HasRows Then
rdr.Read()
For i = 0 To rdr.FieldCount - 1
ReDim Preserve arrValues(i)
arrValues(i) = CStr(rdr.Item(i))
Next
End If
 

thanks for your help!
Kamran

Good Stuff!

-Frinny