List control data filter asp.net

I have a list control. I have data coming from the object. there is field called status id in that object.

I have a drop down box. The drop down contains a status id field.

Initially all the data is being popualted.

When I click on filter by selec开发者_如何学JAVAting an option in the dropdown I want my list to be loaded with the status field equal to the selecetd value value in drop down.

In page load I am using foreach to populate the list control. Where do I put the filter statement in of drop down code. Shall I put it in if(!ispostback) or outside the postback.

Because everytime I select the value from the drop down the list populates with the default values.

Please help me.

From what I have understood from your description, if you will place your filtering code in the page load event than:

• if it's inside an if (!Page.IsPostBack) { } block than it will be executed only when the page is rendered for the first time - but you want to have all data initially and filter later when you have selected an option from the drop down;

• if it is outside of this block it is not right because it will be executed when any control on the page causes a postback not only when you you want to filter by selecting an option from the drop down.

Try to use something like this instead:

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        // executed only first time
        // load data for both list control and drop down
    }        
}

protected void DropDownList_SelectedIndexChanged(object sender, EventArgs e)
{
    // filter the data
    // (or clear the items in the list control and fetch new data for the list 
    // control based on the status id selected in the drop down and rebind it)
}

Don't forget to set AutoPostBack="True" for the drop down control or else SelectedIndexChanged event will not cause a postback and your data will not be filtered when you change the selection (just after some other controls causes a postback).