User Control and member variables

[John Keenan]

I have a user control with 2 buttons on it & 1 label.... as each button is
pressed, they set a member variable within the class and sets the label
test.
I also have a get/set property for the member variable.
At Page_Load time I initialize this member variable

I have a host form which contains the user control
I have a button and a label on the host form (in addition to the user
control)
Now when I click the host-form button, it is suppose to get the property
from the user control and put the contents
into the host-form label.....

the following is from the user control:
private void Page_Load(object sender, System.EventArgs e)
{
mUC1Label= "this is from Page_Load";
}
public string UC1LinkButton
{
get { return mUC1Label; }
set {
mUC1Label = value;
uc1Label1.Text = mUC1Label;
}
}
private void LinkButton1_Click(object sender, System.EventArgs e)
{
UC1LinkButton = "LinkButton1_Click";
}
private void LinkButton2_Click(object sender, System.EventArgs e)
{
UC1LinkButton = "LinkButton2_Click";
}

on the host side:
void Button1_Click(object sender, System.EventArgs e)
{
ucTestLabel1.Text = "from the User Control Below " +
Webusercontrol12.UC1LinkButton;
}

ucTestLabel1 is a host-form control
now Button1_Click is not in the Code-Behind... it is in the form page (if
that makes a difference)

what shows up in ucTestLabel1 always is "this is from Page_Load" ,
never "LinkButton1_Click"; or "LinkButton2_Click";

why?

John

 

[Karl Seguin]

What's happening makes total sense to me. I'm not sure how you think it
should ever say LinkButton1_Click or LinkButton2_Click

Walk through this with me...

Initial Load -->
Page_Load (Host)
Page_Load (User Control) --> Property set to "this is from PAge_Load"

Click On user control LinkButton2 -->
Page_Load (Host)
Page_Load (User Control) --> Property set to "this is from PAge_Load"
LinkButton2_Click (User Control) property set to "LinkButton2"

Click On host Button1-->
Page_Load (Host)
Page_Load (User Control) --> Property set to "this is from PAge_Load"
Button1_Click (Host) --> display property, which was set above to
"Page_Load"


Perhaps in your mind you are thinking that having set property to
"LinkButton2" on the 2nd case, this is what should be shown? If so, there
are 2 things playing against you
(a) User control's page_load is firing and resetting the value to
"Page_Load"
(b) The property isn't preserved between trips...


so to fix (a), we need to change it to:
private void Page_Load(object sender, System.EventArgs e)
{
if (!Page.IsPostBack){
mUC1Label= "this is from Page_Load";
}
}


and to fix (b), we need to somehow persist the value across postback by
storing it somewhere (the viewstate is a good place), remove the field
mUC1Label and change the property to (wherever you use the field, also use
the property):

public string UC1LinkButton
{
get { return (string)ViewState["uc1Label"]; }
set {
ViewState["uc1Label"] = value;
uc1Label1.Text = value;
}
}