stubborn error when trying to merge a table into a dataset - vb.net

Question

I'm trying to track down a .NET error in my little game here.
Here is the error:
ArgumentNullException: 'table' argument cannot be null
System.DataSet.Merge(DattaTable table)
It's occurring on the line below where it tries to merge a table into an existing dataset.
I'm trying to do as many checks as I think I can to determine if the dataset or table are empty, but it continues to error on the ds.Merge line.
Dim ds As DataSet
'getData = simple function that uses SqlConnection & SqlDataAdapter to get data from my database
ds = utils.getData("Sproc_GetGameEncounters")
Dim MonsterDataSet As DataSet
MonsterDataSet = utils.getData("Sproc_MonsterDataSetFromDB")
If Not MonsterDataSet Is Nothing Then
If MonsterDataSet.Tables("TreasureList") Is Nothing OrElse MonsterDataSet.Tables("TreasureList").Rows.Count = 0 Then
'MonsterDataSet.Tables("TreasureList") is empty
Else
ds.Merge(MonsterDataSet.Tables("TreasureList")) 'line where error occurs
End If
End If
Are there more checks I could add to help fix or at least track down this error?
Thanks!

Answer 1

I had the same problem recently. The problem is the adapter, it not get the names of tables. I have a similar function and I'm happy to share it.
You can set the table name after dataset filled, or with TableMappings (here an answer for TableMappings), but I preferred the first way.
Function to fill the dataset
Private Function sql_fillDataset(sql As String, Optional tablesName As String() = Nothing) As DataSet
dim sql_connection As SqlConnection
Dim command As SqlCommand
Dim adapter As New SqlDataAdapter
Dim ds = New DataSet
Try
sql_connection = New SqlConnection("YOUR_CONNECTION_STRING")
sql_connection.Open()
command = New SqlCommand(sql, sql_connection)
adapter.SelectCommand = command
adapter.Fill(ds)
If Not tablesName Is Nothing AndAlso Not ds Is Nothing AndAlso Not ds.Tables Is Nothing AndAlso ds.Tables.Count = tablesName.Length Then
For i = 0 To ds.Tables.Count - 1
ds.Tables(i).TableName = tablesName(i)
Next
End If
command.Dispose()
adapter.Dispose()
sql_connection.Close()
sql_connection.Dispose()
Return ds
Catch ex As Exception
Return Nothing
End Try
End Function
How to use it
Dim ds As New Dataset
ds = sql_fillDataset("SELECT * FROM TABLE1")
' #### Here is your case, and you haven't the table name
ds.tables(0)
Or
Dim ds As New Dataset
ds = sql_fillDataset("SELECT * FROM TABLE1", New String() {"TABLE1"})
' #### Here is your solution, but the dataset have the name !!
ds.tables("TABLE1")
Or with more than one tables
Dim ds As New Dataset
ds = sql_fillDataset("SELECT * FROM TABLE1; SELECT * FROM TABLE2", New String() {"TABLE1", "TABLE2"})
ds.tables("TABLE1")
ds.tables("TABLE2")
Hope this help you.