组合框 SelectionChangedEvent 不会写入类字段

Question

I have a problem with writing data to class field. I declared field "rcbSelection" and then initialize it in Page_load(). Then I try to add data in it in some combobox SelectionChangedEvents.

public partial class AddToProcurementPlan : Page
{
    Dictionary<string, int?> rcbSelection;
    protected void Page_Load(object sender, EventArgs e)
    {
        try
        {
            rcbSelection = new Dictionary<string, int?>();
            /*other code*/
        }
     }

    protected void rcb_FinancingBudget_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("financingbudget"))
            rcbSelection["financingbudget"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("financingbudget", int.Parse(rcb.SelectedValue));
    }

    protected void rcb_BudgetName_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("budget"))
            rcbSelection["budget"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("budget", int.Parse(rcb.SelectedValue));
    }

    protected void rcb_FondName_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("fond"))
            rcbSelection["fond"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("fond", int.Parse(rcb.SelectedValue));
    }

    protected void rcb_Kfkr_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("kfk"))
            rcbSelection["kfk"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("kfk", int.Parse(rcb.SelectedValue));
    }

    protected void rcb_Kekr_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("kekr"))
            rcbSelection["kekr"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("kekr", int.Parse(rcb.SelectedValue));
    }

    protected void rcb_BudgetExec_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("budgetexec"))
            rcbSelection["budgetexec"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("budgetexec", int.Parse(rcb.SelectedValue));
    }

    protected void rcb_SectionCode_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("section"))
            rcbSelection["section"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("section", int.Parse(rcb.SelectedValue));
    }

    protected void rcb_TargetArticle_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
    {
        RadComboBox rcb = (RadComboBox)sender;
        if (rcbSelection.ContainsKey("targetarticle"))
            rcbSelection["targetarticle"] = int.Parse(rcb.SelectedValue);
        else
            rcbSelection.Add("targetarticle", int.Parse(rcb.SelectedValue));
    }
}

But when I set stop point on last event I can see that rcbSelection is empty. What i doing wrong? Help me please.

Answer 1

I suspect your rcbSelection dictionary is being reset after the postbacks of your SelectedIndexChanged events since the dictionary isn't being persisted in some sort of in memory storage like ViewState.

Consider persisting your rcbSelection dictionary like...

        private Dictionary<string, int?> rcbSelection
        {
            get
            {
                if(this.ViewState["rcbSelection"] != null)
                {
                    return (Dictionary<string, int?>)this.ViewState["rcbSelection"];
                }

                return new Dictionary<string, int?>();
            }

            set
            {
                this.ViewState["rcbSelection"] = value;
            }
        }

Also in your page_load event if you don't want the dictionary to be reset after each postback consider removing rcbSelection = new Dictionary<string, int?>(); from your page_load function or initializing only once by checking if it's the first page load by...

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!this.IsPostBack)
            {
                rcbSelection = new Dictionary<string, int?>();
            }

            // other postback code here ... 
        }

Hope that helps.