Help on DataSets

Discussion in 'ASP .Net Datagrid Control' started by cagriandac@gmail.com, Jul 22, 2006.

  1. Guest

    Hello,

    I am creating an application using asp.net 2.0. But I am stuck
    somewhere. I want to get values from a DataSet one by one on every
    Page_Load. So I wrote my code in Page_Load but it didnt work, giving a
    warning. Here is my code:

    Code:
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As
    System.EventArgs) Handles Me.Load
    Dim ds As DataSet1
    Dim test As String
    test = ds.Tables("pictureID").Rows(0)("pictureID").ToString
    Label1.Text = test
    End Sub
    
    And the Warning:

    Variable 'ds' is used before it has been assigned a value. A null
    reference exception could result at runtime.


    How can I handle this warning. Did I wrote the code in wrong place?

    I created my DataSet using the menu in Visual Web Developer (Visual
    Studio 2005). So I did not write any code for it.

    Am I assigning the ds right?
    I also assigned it as DataSet1TableAdapter. But it didnt work also. I
    am a rookie and any help is appreciated.
     
    , Jul 22, 2006
    #1
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  2. Dim ds As DataSet1 creates a new dataset. It has no connection with the one
    you have created. You should be able to use the created one just by its
    name. I am not familiar with Visual Web Developer, but usually what you
    create is the schema for the dataset. On top of this, you need to load
    actual data. And you have to make sure that the dataset gets populated on
    every postback. For this you will have to either re-load it on every
    postback or save it in a persistent location such as a session variable.

    --
    Eliyahu Goldin,
    Software Developer & Consultant
    Microsoft MVP [ASP.NET]

    <> wrote in message
    news:...
    > Hello,
    >
    > I am creating an application using asp.net 2.0. But I am stuck
    > somewhere. I want to get values from a DataSet one by one on every
    > Page_Load. So I wrote my code in Page_Load but it didnt work, giving a
    > warning. Here is my code:
    >
    >
    Code:
    >    Protected Sub Page_Load(ByVal sender As Object, ByVal e As
    > System.EventArgs) Handles Me.Load
    >        Dim ds As DataSet1
    >        Dim test As String
    >        test = ds.Tables("pictureID").Rows(0)("pictureID").ToString
    >        Label1.Text = test
    >    End Sub
    > 
    >
    > And the Warning:
    >
    > Variable 'ds' is used before it has been assigned a value. A null
    > reference exception could result at runtime.
    >
    >
    > How can I handle this warning. Did I wrote the code in wrong place?
    >
    > I created my DataSet using the menu in Visual Web Developer (Visual
    > Studio 2005). So I did not write any code for it.
    >
    > Am I assigning the ds right?
    > I also assigned it as DataSet1TableAdapter. But it didnt work also. I
    > am a rookie and any help is appreciated.
    >
     
    Eliyahu Goldin, Jul 23, 2006
    #2
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