ViewState Question

[wey97]

Dim str As String
 
    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Put user code to initialize the page here
 
        If Page.IsPostBack Then
            str = ViewState("str")
        Else
            str = "Init"
        End If
 
        Response.Write(str)
 
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        str = TextBox1.Text
        ViewState("str") = str
    End Sub

When the page first loads, obviously "Init" prints. Then, I type in TextBox1 and click Button1. You would think that on the first PostBack, str would be printed but it isn't. It's not until the next Button1 click. So my question is, does the Page PostBack fire before the Button Click event fires? Seems to be backwards if that's the case...

[nemaroller]

The page load occurs before the button_click event.

So what's happening is:
1) Its set to init
2) You then type in something and click submit
3) Page_Load fires, viewstate is empty
4) The button click event fires, viewstate now contains the value
5) The page renders, you click submit again
6) The Page_Load fires again, and the value from viewstate is retrieved

Its not backwards actually.
Remove the response.write in the page load, and place it here instead:

Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.PreRender
       If Page.IsPostBack Then
         str=viewstate("whatever")
       End If
          Response.Write(str)
 End Sub

That said, this not the best way to store values in viewstate and retrieve them, but for your example, its how to implement it fast.

[wey97]

Can you give me a solid example on ViewState?