Why empty cell throws an error during SQL stored procedure execution

Question

SELECT
    CAST ([content_html] AS XML).query(\'/root/Physicians/specialty/a\') AS [Specialty1]
    , CAST ([content_html] AS XML).query(\'/root/Physicians/specialty2/a\         


        

Answer 1

You can add something like this to the code behind of the page:

protected object MyEval(string expression)
{
    object o = null;
    try
    {
        o = DataBinder.Eval(this.GetDataItem(), expression);
    }
    catch
    {
        o = System.String.Empty;
    }
    return o;
}

and then replace all Evals with "MyEval":

<asp:Label ID="lblSpec1" runat="server"><%# MyEval("Specialty1").ToString() + DisplayMultiplMyEvalues(MyEval("Specialty2").ToString()) + DisplayMultiplMyEvalues(MyEval("Specialty3").ToString()) + DisplayMultiplMyEvalues(MyEval("Specialty4").ToString()) + DisplayMultiplMyEvalues(MyEval("Specialty5").ToString()) + DisplayMultiplMyEvalues(MyEval("Specialty6").ToString()) %></asp:Label>

Answer 2

As Gerbenny stated to say in the comments. DBNull won't be picked up by String.IsNullOrEmpty. DBNull is handled differently. to put it in code terms.

DBNull.Value != null

So basically You need to check if an Item is DBNull before trying to display or preforming any actions on it.

Essentially

    <%# Eval("Specialty1") != DBNull.Value ? Eval("Specialty1").ToString() : String.Empty + DisplayMultipleValues(Eval("Specialty2") != DBNull.Value ? Eval("Specialty2").ToString() : String.Empty)
 + etc... %>

Answer 3

In case your problem is caused by NULL values, then you can solve your problem with sth like:

public string DisplayMultipleValues(object strValue)
{
   if (strValue == null)
      return "";
   else
      return (NonBlankValueOf(strValue.ToString()));
}

Your Eval statements should look like this:

<%# Eval("Specialty1") == null ? "" : Eval("Specialty1").ToString() + 
    DisplayMultipleValues(Eval("Specialty2")) + etc ...

Answer 4

The stack trace and error message you provided state exactly why it isn't working. It says

DataBinding: 'System.Data.DataRowView' does not contain a property with the name 'Specialty3'.

which is coming out of

...
System.Web.UI.DataBinder.Eval(Object container, String[] expressionParts) +142
...

which means it is erroring where you are doing Eval("Specialty3").

What all this boils down to is that the data set coming back from your database doesn't contain a column named Specialty3. It could be from a misspelling, from not updating a proc or for a number of other reasons.