asp.net中静态或共享方法中的访问控制值

Question

let say you have static method in which you want to access the dropdownlist selected value textbox value and some other controls value.. my problem is that i am always getting first selected value of dropdownlist even whatever value i select in dropdown

what i did i create a property of dropdownlist then get a value in page_Load event then pass this value into static method

    Partial Public Class stocklist
        Inherits System.Web.UI.Page

    'Static or shared Property'

        Private Shared _make As DropDownList

        Public Shared Property MAKE() As DropDownList
            Get
                Return _make
            End Get
            Set(ByVal value As DropDownList)
                _make = value
            End Set
        End Property

    'Page Load'

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
          'ddlMake is the dropdownlist and MAKE is a Property'

                  MAKE = ddlMake
    End Sub

    'Static or shared Web Method'
   <WebMethod()> _
    Public Shared Function Select_Search() As SearchParameters()
        Dim JSON As New List(Of SearchParameters)()

        Dim dtst As New DataTable()


        Dim myList As New dsStockTableAdapters.newSTOCK_LISTTableAdapter()
        dtst = myList.GetData(MAKE.SelectedValue, "0", "0", "0", "0", DisplayType, "", "", "", "Any", "", "", "", "", "", 0, "", "", 0, "")




        Try
            For Each rdr As DataRow In dtst.Rows
                Dim SRCH As New SearchParameters()
                SRCH.CHASSIS_NO = rdr("CHASSIS_NO").ToString()
                SRCH.MODEL = rdr("MODEL").ToString()
                SRCH.color = rdr("color").ToString()
                SRCH.TRANSMISSION = rdr("TRANSMISSION").ToString()
                SRCH.DOOR = rdr("DOOR").ToString()
                SRCH.MAKE = rdr("MAKE").ToString()
                SRCH.Image1 = rdr("Image1").ToString()
                SRCH.MODEL_DESCRIPTION = rdr("MODEL_DESCRIPTION").ToString()

                JSON.Add(SRCH)


            Next
        Catch

        Finally
        End Try
        Return JSON.ToArray()
    End Function
End Class

Now a "MAKE" property always showing the first selected value which is 0 infect i am selecting the other value in dropdownlist but it`s always showing first value "0" while debuging.

how to access the dropdownlist selected value in static method???

Answer 1

Instead of trying to get the value from the server control in the static page method, have jQuery get the selected value and send it to your page method, like this:

$(document).ready(function() {
    var selectedMake = $('#<%= MAKE.ClientID %>' option:selected").text();

    var args = {
        theMake : selectedMake
    }

    $.ajax({
        type: "POST",
        url: "YourPageName.aspx/Select_Search",
        data: JSON.stringify(args),
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function(result) {
            // Do something with result here
        }
    });
});

This requires a change to the static web method, in order to allow it to accept a parameter now, like this:

'Static or shared Web Method'
<WebMethod()> _
Public Shared Function Select_Search(theMake As String) As string
    Dim dtst As New DataTable()
    Dim List As New dsStockTableAdapters.newSTOCK_LISTTableAdapter()
    dtst = List.GetData(theMake)
    Return dtst
End Function

Now you do not have to attempt to find the value of the server control in a static method, because it was sent to the static method as a parameter.

Notes:

• The JSON.stringify function is part of the [JSON.js library]>>( https://github.com/douglascrockford/JSON-js )
• The example above makes extensive use of jQuery, make sure you have a reference in your page or master page, if you are using them, to the jQuery script file
• I am not sure what you are actually doing in your page method, because it is declared as returning a String, but it appears to trying to return a List, along with an unused Catch block, I deleted the unused Catch and Finally blocks and had it return the dtst object, feel free to correct this as needed.

---

UPDATE:

The only option you have server-side to allow access to the value in the Static web method is to use Session cache to store the drop down's selected value when it is changed via the drop down's SelectedIndexChanged event, like this:

Sub Index_Changed(sender As Object, e As EventArgs)        
    Session("SelectedMakeValue") = ddlMake.SelectedItem.Value
End Sub

Now you must give the Static web method access to the Session cache, like this:

'Static or shared Web Method'
<WebMethod(EnableSession := True)> _
Public Shared Function Select_Search() As string
    Dim dtst As New DataTable()
    Dim List As New dsStockTableAdapters.newSTOCK_LISTTableAdapter()
    Dim theMake As String = HttpContext.Current.Session("SelectedMakeValue").ToString()
    dtst = List.GetData()
    Return dtst
End Function

Note: You must use the fully qualified name for the Session object, which is HttpContext.Current.Session ; otherwise you will get errors.