How to conditionally change a control property in the presentation layer

I'm not very experienced in ASP.Net, as I work mostly with PHP. I'm trying this, but it doesn't work:

<asp:TextBox runat="server" ID="txtAnswer" 
  TextMode='<%# IIf(DataBinder.Eval(Container.DataItem, "DoLargeInput"), "MultiLine", "SingleLine" )%>' Text=''></asp:TextBox>

DoLargeInput is a boolean.

Why doesn't this work?

I'm gettin the following error:

System.InvalidCastException: Conversion from string "MultiLine" to type 'Integer' is not valid. ---> System.FormatException: Input string was not in a correct format.
   at Microsoft.VisualBasic.CompilerServices.Conversions.ParseDouble(String Value, NumberFormatInfo NumberFormat)
   at Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(String Value)
   --- End of inner exception stack trace ---
   at Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(String Value)
   at Microsoft.VisualBasic.CompilerServices.Conversions.ToInteger(Object Value)
   at ASP.profile_questions_aspx.__DataBinding__control6(Object sender, EventArgs e)
   at System.Web.UI.Control.OnDataBinding(EventArgs e)
   at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding)
   at System.Web.UI.Control.DataBind()
   at System.Web.UI.Control.DataBindChildren()
   at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding)
   at System.Web.UI.Control.DataBind()
   at System.Web.UI.WebControls.Repeater.CreateItem(Int32 itemIndex, ListItemType itemType, Boolean dataBind, Object dataItem)
   at System.Web.UI.WebControls.Repeater.CreateControlHierarchy(Boolean useDataSource)
   at System.Web.UI.WebControls.Repeater.OnDataBinding(EventArgs e)
   at System.Web.UI.WebControls.Repeater.DataBind()
   at profile_questions.LoadObjects()

Any help would be greatly appreciated. Thanks!

From stackoverflow

• Try:-

  IIf(DataBinder.Eval(Container.DataItem, "DoLargeInput"), TextBoxMode.MultiLine, TextBoxMode.SingleLine
  

  It the parse that will convert TextMode="MultiLine" approriately for you. At the point this binding code happens the parseing is over, you need to specify the value as you would in code.

  Infinity : Great that works thanks. So TextBoxMode.MultiLine is a global constant?

  AnthonyWJones : TextBoxMode is an Enumeration type containing the set of valid values for the TextBox controls TextMode property. Its available in the System.Web.UI.WebControls namespace. The value's global name is actually System.Web.UI.WebControls.TextBoxMode.MultiLine

  Infinity : Thanks for the explanation

• The failed conversion to 'Integer' is because the TextMode property is a .NET enum, which is represented internally as an integer. TextBoxMode.MultiLine and TextBoxMode.SingleLine represent the correct kind of value.

  On MSDN you can see the TextBox.TextMode property has type TextBoxMode.