Windows app Datarow error

[cpopham]

I am writing an application where my user makes a selection with a combo box and then it pulls up the appropriate information for the selection. If the user approves of the selection he clicks a button which adds the information to another dataset.

 

Everything works fine except when the button is clicked to add the information to the dataset.

 

I get the error Object reference not set to an instance of an object.

 

Here should be the appropriate code:

 

This is the button to add the information to the dataset. The DataTier is a separate class for all of my data manipulation.

 

Private Sub btnAddPO_Click(ByVal sender As Object, _

ByVal e As System.EventArgs) _

Handles btnAddPO.Click

Dim ds As DataSet

Dim strDate As Date = Today

Dim strPO As String = mstrSelectedPO

Dim strSpend As String = Me.lblSpend.Text

Dim strVend As String = Me.lblVendor.Text

Dim strBuy As String = Me.lblBuyer.Text

 

mobjDataTier = New DataTier

ds = mobjDataTier.AddAGPO(strDate, strPO, strSpend, strVend, strBuy)

 

Me.dgAGPOs.DataSource = ds

Me.dgAGPOs.DataMember = "AGPOInfo"

Me.dgAGPOs.Refresh()

End Sub

 

This is the code in my data class which is giving me the error:

 

 

Public Function AddAGPO(ByVal strDate As String, _

ByVal strPONum As String, _

ByVal strSpend As String, _

ByVal strVend As String, _

ByVal strBuyer As String) _

As DataSet

Try

If blnCreated = False Then

dsAGPOs = New DataSet

With dsAGPOs.Tables.Add("AGPO")

.Columns.Add("ToAG", GetType(String))

.Columns.Add("PONum", GetType(String))

.Columns.Add("Vendor", GetType(String))

.Columns.Add("Buyer", GetType(String))

End With

 

blnCreated = True

End If

 

Dim myRow As DataRow

 

myRow = dsAGPOs.Tables("AGPOInfo").NewRow �This is the row that is causing the error.

 

myRow.Item(0) = strDate

myRow.Item(1) = strPONum

myRow.Item(2) = strSpend

myRow.Item(3) = strVend

myRow.Item(4) = strBuyer

 

dsAGPOs.Tables("AGPOInfo").Rows.Add(myRow)

 

Return dsAGPOs

 

 

Catch ex As Exception

MessageBox.Show(ex.Message)

 

End Try

 

End Function

 

Any Ideas?

Chester

[PlausiblyDamp]

When you get this error what is the value of dsAGPOs and dsAGPOs.Tables("AGPOInfo") in the debugger?

[cpopham]

It says:

 

<NewDataSet />

 

That is using debug.writeline(dsAGPOs.GetXML right before I declare the myRow variable.

[PlausiblyDamp]

Looks like the AGPOInfo table hasn't been created.

[cpopham]

At the module layer I use:

Private dsAGPOs as dataset

 

to declare the dataset. I want it to remain until the program is terminated because my users will continue to add datarows to the dataset.

 

I then have this if statement which checks a boolean value to see if this is the first run through or not and if is the first run through it is suppose to create the dataset:

Try

If blnCreated = False Then

dsAGPOs = New DataSet

With dsAGPOs.Tables.Add("AGPO")

.Columns.Add("ToAG", GetType(String))

.Columns.Add("PONum", GetType(String))

.Columns.Add("Vendor", GetType(String))

.Columns.Add("Buyer", GetType(String))

End With

 

blnCreated = True

End If

 

Shouldn't that create the dataset? If not what do I need to change to create the dataset?

 

Chester

[PlausiblyDamp]

Looks like you are creating a table called AGPO but refering to one called AGPOInfo for starters. Also if you step through the code in the debugger does it call into the above routine correctly? Also where is blnCreated declared / accessed?

[cpopham]

Referring to the wrong datatable was the problem. I must have looked at that code 50 times and did not catch that problem! The boolean variable is created at the module level of the datatier.

 

But my datatable keeps getting remade. I am trying to figure out how to keep this from happening. Maybe turn this function to to seperate functions one to create the dataset and another to update the datatable using a counter in the main form?

 

Chester