Dataset code...is this correct?

  • Thread starter Thread starter John Pether
  • Start date Start date
J

John Pether

ok, I am trying to make one call to the db and create a datalist and then
populate a datalist and a datagrid with different filtered versions of the
dataset. I presume this is a better way of doing it than making two seperate
calls to the db where I could just use 2 stored procs to filter the data.
Any help or advice if I'm doing it the wrong way would be appreciated.

' Obtain Link information from Links table

Dim links As New DNSite.LinksDB()

Dim myDS As DataSet

myDS = links.GetLinks(CatID)

' filter dataset for premier links

' and bind to the datalist control

plusdl.DataSource = myDS.Tables("tblLinks").Select("TypeName = Premier
Plus")

plusdl.DataBind()

' bind remaining links to DataGrid

premierDG.DataSource = myDS.Tables("tblLinks").Select("TypeName <> Premier
Plus")

premierDG.DataBind()

-----------------------------------
I get the following error:
-----------------------------------

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the
current web request. Please review the stack trace for more information
about the error and where it originated in the code.

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

Source Error:

Line 88: ' and bind to the datalist control
Line 89:
Line 90: plusdl.DataSource =
myDS.Tables("tblLinks").Select("TypeName = Premier")
Line 91: plusdl.DataBind()

Source File: **********\DNSLinks.ascx.vb Line: 90

Stack Trace:
[NullReferenceException: Object reference not set to an instance of an
object.]
ASPNetPortal.DNSLinks.BindGrid() in ********\DNSLinks.ascx.vb:90
ASPNetPortal.DNSLinks.Page_Load(Object sender, EventArgs e) in
********\DNSLinks.ascx.vb:76
System.Web.UI.Control.OnLoad(EventArgs e) +67
System.Web.UI.Control.LoadRecursive() +29
System.Web.UI.Control.LoadRecursive() +92
System.Web.UI.Control.LoadRecursive() +92
System.Web.UI.Control.LoadRecursive() +92
System.Web.UI.Page.ProcessRequestMain() +724
 
Judging by the error message, I would say that the variable "plusTable" on
line 93 is Nothing which means that your dataset does not contain a table
called "tblLinks".

Kathleen Dollard said:
John,

* Line 92: Dim plusView As NEW DataView

(VB will fix the casing )

--
Kathleen (MVP-VB)



John Pether said:
Ok I am now using the datview as suggested but get the following error:
Exception Details: System.NullReferenceException: Object reference not set
to an instance of an object.

Source Error:
Line 91: plusTable = myDS.Tables("tblLinks")
Line 92: Dim plusView As DataView
Line 93: plusView = plusTable.DefaultView
Line 94: plusView.RowFilter = "TypeName = Premier Plus"
Line 95:
Source File: ******\DNSLinks.ascx.vb Line: 93
Stack Trace:
[NullReferenceException: Object reference not set to an instance of an
object.]
DNSite.DNSLinks.BindGrid() in ******\DNSLinks.ascx.vb:93
DNSite.DNSLinks.Page_Load(Object sender, EventArgs e) in
******\DNSLinks.ascx.vb:76
System.Web.UI.Control.OnLoad(EventArgs e) +67
System.Web.UI.Control.LoadRecursive() +29
System.Web.UI.Control.LoadRecursive() +92
System.Web.UI.Control.LoadRecursive() +92
System.Web.UI.Control.LoadRecursive() +92
System.Web.UI.Page.ProcessRequestMain() +724

---------------------
The code is below:
---------------------

<code>
' Obtain Link information from Links table

Dim links As New DSN.LinksIndexDBbak()

Dim myDS As DataSet

myDS = links.GetLinks(CatID)

' filter dataset for premier plus links

' and bind to the datalist control

Dim plusTable As DataTable

plusTable = myDS.Tables("tblLinks")

Dim plusView As DataView

plusView = plusTable.DefaultView

plusView.RowFilter = "TypeName = Premier Plus"

plusdl.DataSource = plusView

plusdl.DataBind()

' filter dataset for remaining links

' and bind to the datalist control

Dim basicTable As DataTable

basicTable = myDS.Tables("tblLinks")

Dim basicView As DataView

basicView = basicTable.DefaultView

basicView.RowFilter = "TypeName = Basic, Premier"

premierDG.DataSource = plusView

premierDG.DataBind()
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