Object reference not set to an instance of an object.

[farooqhussain786]

"Object reference not set to an instance of an object."

I had receive the above mention error I have load printer info in first combo box and when select value a event triggered and load values in second combo box using printer info but i am receiving subject mention error.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        'txtUPCode.Attributes.Add("onclick", "showDiv('divQtyAddSidebar');")
        'txtUPCode.Attributes.Add("onfocus", "showDiv('divQtyAddSidebar');")
        'txtUPCode.Attributes.Add("onblur", "hideDiv('divQtyAddSidebar', this.value);")
 
        txtProductSearch.Attributes.Add("onfocus", "showDiv('divSearchSidebar');")
        txtProductSearch.Attributes.Add("onblur", "hideDiv('divSearchSidebar', this.value);")
 
 
 
        If Not IsPostBack Then
            ''Load Brand Name
            ddlSelectBrand.DataSource = wseCommerce.LoadBrand().Tables(0)
            ddlSelectBrand.DataTextField = wseCommerce.LoadBrand().Tables(0).Columns("ManufacturerName").ColumnName.ToString()
            ddlSelectBrand.DataValueField = wseCommerce.LoadBrand().Tables(0).Columns("ManufacturerCode").ColumnName.ToString()
            ddlSelectBrand.DataBind()
        End If
 
        LoadPageStateFromPersistenceMedium()
    End Sub
 
    Protected Sub ddlSelectBrand_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlSelectBrand.SelectedIndexChanged
        If ddlSelectBrand.SelectedValue <> "" Then
            ddlSelectCatridge.Enabled = True
            ddlSelectPrinter.Enabled = True
 
            'Load Printer against Brand Name
            Dim BrandName As String = ddlSelectBrand.SelectedItem.Text.ToString
            ddlSelectPrinter.DataSource = wseCommerce.LoadPrinter(BrandName).Tables(0) 'error Object reference not set to an instance of an object. 
            ddlSelectPrinter.DataValueField = wseCommerce.LoadPrinter(BrandName).Tables(0).Columns("PrinterName").ColumnName.ToString()
            ddlSelectPrinter.DataTextField = wseCommerce.LoadPrinter(BrandName).Tables(0).Columns("PrinterName").ColumnName.ToString()
            ddlSelectPrinter.DataBind()
        Else
            ddlSelectCatridge.Enabled = False
            ddlSelectPrinter.Enabled = False
        End If
    End Sub

[mzmishra]

did you check if this statement has any tables . wseCommerce.LoadPrinter(BrandName)

[Frinavale]

ASP.NET runs in a stateless environment. That means that when a request to the page occurs (whether it be the first time the page is loaded or because of a postback) all of the objects required in order to process the page are created...and when the response is sent to the browser, everything is destroyed.

This means that wseCommerce does not exist unless you recreate it on subsequent page requests. It might be a good idea to store the results in Session or something so that you don't have to recreate it by connecting to the database.

-Frinny