Preserving user control on autopostback asp.net - asp.net

Question

I have two user controls: dsucTopLeft and dsucTopRight in an aspx page. Each of the user controls has a dropdownlist to select values from.
The aspx page has a button "Save".
In the OnClickEvent of the button, I take data from those user controls (which return the values from the drop down list). I need to insert these values into database. However, these values set to 0 after the button is clicked.
How would I preserve those values?
Code:
ParentTemplate.aspx
<div class="leftDashboard">
<uc:dsuc ID="dsucTopLeft" runat="server" />
</div>
<div id="rightDashboard">
<uc:dsuc ID="dsucTopRight" runat="server" />
</div>
It also has a button:
<asp:Button ID="SaveButton" runat="server" OnClick="SaveButton_Click" Text="Save Dashboard" />
This is the codebehind for the button:
protected void SaveButton_Click(object sender, EventArgs e)
{
//If the mode is "CREATE", then it needs to insert the information about dashboard and the charts it contains
for (int i = 0; i < dsuc.Length; i++)
{
dsuc[i].dashboardId = dashboardId;
if (dsuc[i].chartId != 0) //Here, the chartId remains 0
dsuc[i].insert();
}
}
dsuc is an array. It is being populated in the following way:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
dsuc[0]=dsucTopLeft;
dsuc[1]=dsucTopRight;
}
}
UserControl:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
initializeDropDownList();//It initializes the drop down list
}
}
public void insert()
{
//It inserts into database
}
protected void chartDDLSelectedIndexChanged(object sender, EventArgs e)
{
oldChartId = chartId;
String chartTitle = chartDropDownList.SelectedItem.Text;
if (chartTitle != dropDownMessage)
{
chartId = int.Parse(chartDropDownList.SelectedItem.Value);
//Chart user control should be retrieved from the database and drawn.
chartTitleLabel.Text += "chart id : " + chartId.ToString() + " title: " + chartTitle;
//chartUserControl.Visible = true;
}
}
The user control i.e. the class of dsuc[] changes its chartId when an item in its drop down list is selected. I printed the value, it works. But that same value becomes 0 when the button in clicked.

Answer 1

Remove the if (!Page.IsPostBack)from
if (!Page.IsPostBack)
{
dsuc[0]=dsucTopLeft;
dsuc[1]=dsucTopRight;
}
If not, it will only populate it when is not post back. As a click produces a post back, you'll want that code being executed :)
Also, it is probably that your clickp event is being called beforeselectedindexchanged`. In that case, the code that sets chartId is not executed (yet) when the click event is fired. You can solve that doing this:
public int ChartId { get { return int.Parse(chartDropDownList.SelectedItem.Value); }}
and calling that property instead. Also, you can use that property in your selectedindexchanged event handler