Help on DataSets

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  • Dot Net Daddy

    #1

    Help on DataSets

    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 DataSet1TableAd apter. But it didnt work also. I
    am a rookie so any help is appreciated.

  • Cor Ligthert [MVP]

    #2
    Re: Help on DataSets

    DotNetDaddy,

    If you want to get individual results focus you than on the datatable. The
    dataset is just a very extended wrapper arround that (and around the
    relations to that).

    Your error is because "ds" in your code is only a placeholder address for an
    object which is not filled yet (Is Nothing). You have to set it to, to the
    actual object as is created. (Or use that direct)

    Cor

    "Dot Net Daddy" <cagriandac@gma il.comschreef in bericht
    news:1153598571 .054394.64430@m 73g2000cwd.goog legroups.com...
    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 DataSet1TableAd apter. But it didnt work also. I
    am a rookie so any help is appreciated.
    >

    Comment

    • tomb

      #3
      Re: Help on DataSets

      You need to make ds = New DataSet1, then populate the dataset with data.

      T

      Dot Net Daddy wrote:
      >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 DataSet1TableAd apter. But it didnt work also. I
      >am a rookie so any help is appreciated.
      >
      >
      >

      Comment

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