Need help removing this fudged code... Binding user control on postback

Question

As per the title, I know the code I've posted below is utter poo, this is why I need your help!

I've put way too many hours into this, and it's either down to inexperience, a bug or I've screwed up somewhere.

I have a user control with a view properties that access the ViewState and two user controls within that display the properties.

Within the page_load of the user control, depending on the value of some of the properties, it will toggle the visibility of the controls within:

public partial class PatientStatus : System.Web.UI.UserControl
{
    public string PatientName { get { return ViewState["PatientName"] as string; } set { ViewState["PatientName"] = value; } }
    public bool ClinicianView { get { return Convert.ToBoolean(ViewState["ClinicianView"]); } set { ViewState["ClinicianView"] = value; } }
    public string RangeTitle { get { return ViewState["RangeTitle"] as string; } set { ViewState["RangeTitle"] = value; } }
    public int? RangeLimitNormSys { get { return ViewState["RangeLimitNormSys"] as int?; } set { ViewState["RangeLimitNormSys"] = value; } }
    public int? RangeLimitNormDia { get { return ViewState["RangeLimitNormDia"] as int?; } set { ViewState["RangeLimitNormDia"] = value; } }

    protected void Page_Load(object sender, EventArgs e)
    {
        bool ispostback = IsPostBack;
        if (ispostback && ((System.Web.UI.WebControls.Repeater)(this.Parent.Parent)).DataSource != null)
        {
            object itm = ((RepeaterItem)this.Parent).DataItem;
            if (itm is AppointmentRow)
            {
                AppointmentRow row = itm as AppointmentRow;
                PatientName = row.Name;
                RangeTitle = row.Range;
                RangeLimitNormDia = row.RangeLimitNormDia;
                RangeLimitNormSys = row.RangeLimitNormSys;
                ispostback = false;
            }
            else if (itm is ReadingRow)
            {
                ReadingRow row = itm as ReadingRow;
                PatientName = row.Name;
                RangeTitle = row.Range;
                RangeLimitNormDia = row.RangeLimitNormDia;
                RangeLimitNormSys = row.RangeLimitNormSys;
                ispostback = false;
            }
            else if (itm is PatientRow)
            {
                PatientRow row = itm as PatientRow;
                PatientName = row.Name;
                RangeTitle = row.Range;
                RangeLimitNormDia = row.RangeLimitNormDia;
                RangeLimitNormSys = row.RangeLimitNormSys;
                ispostback = false;
            }
        }
        if (!ispostback)
        {
            if (!string.IsNullOrWhiteSpace(RangeTitle))
            {
                placeHolder.Visible = true;
                literalNA.Visible = false;
            }
        }
    }
}

Previously the Page_Load event simply contained:

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        if (!string.IsNullOrWhiteSpace(RangeTitle))
        {
            placeHolder.Visible = true;
            literalNA.Visible = false;
        }
    }
}

But on postback, the RangeTitle property was always null, so even when removing the isPostBack statement, it didn't work property.

The only way to resolve it, was to really fudge it by the first block of code.

On the Page_Load of the parent page, and on !isPostBack I'm calling a method that gets and binds data to the repeater. This works fine. But on a postback, i'm calling the same method and for some reason, the user control isn't populating.

Any idea's?

Merry Christmas

Gav

Edit

In response to @jwiscarson

I have a table that is generated via an ASP:Repeater and within the ItemTemplate, I have added a User Control which contains a PlaceHolder and a Literal. Also within the User Control is a number of Properties.

Then on databind I pass across a number of values to the user control (I've tried both OnItemDataBound and inline using Eval). Then on the User Control's Page_Load event, as per the second block of code above, I first check if it's a postback, if not, I then check to see if the Property RangeTitle has a value.

If RangeTitle does not have a value, I then hide the placeholder that contains HTML that would display the RangeTitle and show a literal that displays N/A.

When loading the page for the first time, (!isPostBack) it works fine. But as soon as I create a postback, the User Controls within the repeater all revert to N/A even when their RangeTitle properties had a value.

On debugging, I set a breakpoint in the Page_Load of the User Control. When I first load the page, I can see that my properties have been populated correctly. Then on postback, Page_Load is called on the UserControl and the properties are populated correctly, then Page_Load is called again, but this time, the properties are empty.

i.e.

!isPostBack UserControl::Page_Load < Correct data

isPostBack UserControl::Page_Load < Correct data myButton_Click (bind new data) UserControl::Page_Load < No data

To make things even more confusing. The method called within myButton_Click to bind the data, is the exact same method called in the Page_Load of the Page to populate the repeater on !isPostBack

Thanks ;)

jwheron jwheron · Accepted Answer · 2011-12-23T18:41:50

I would check to make sure that DataItem is accessible in this function. I think you need to listen to the ItemDataBound event and perform this work in that event.

Beyond that, it's difficult to suggest anything else concrete. I don't really understand why you're doing what you're doing (if you have this information in a Repeater, why does it also need to be in ViewState?). If you could explain your rationale for doing this, it might help me and anyone else who visits this question. You say that you're just trying to show/hide some specific items on the page. This is pretty complicated code without a lot of justification for that complication.

As an aside: you really, really need to break this code down and think about what you're trying to accomplish. Here are a few suggestions:

Separate the scopes inside your if and else if statements into functions that return the data you need.
Do not include lines like ((System.Web.UI.WebControls.Repeater)(this.Parent.Parent)).DataSource != null in an if statement. Perform this cast separately and store it in a variable, or write a small function that checks this.
Statements like this.Parent.Parent and other references to Parent controls are code smells, in my opinion. Even on a normal page, this would be a code smell, but what exactly is this.Parent going to reference when you include it in a UserControl?

Need help removing this fudged code... Binding user control on postback

1 Answers