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POSpecified Cast is not valid when DataBind to Nullable DateTimeOffset and field is NULL
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  1. POSpecified Cast is not valid when DataBind to Nullable DateTimeOffset and field is NULL
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    copied!<p>I've created a simple CompositeControl and exposed a Nullable DateTimeOffset property. I'm binding the control to a SQL Server DateTimeOffset field using</p> <pre><code>DateTimeOffset='&lt;%# Bind("myDateTimeOffsetField") %&gt;' </code></pre> <p>This works great when the DateTimeOffset field has a value. But when the field is NULL I get a "Specified Cast is not valid" error.</p> <p>How do I stop this error and set my property to Nothing when the field is NULL?</p> <p>I thought this would be the default behaviour!</p> <p>Property definition is:</p> <pre><code>Public Property DateTimeOffset As DateTimeOffset? </code></pre> <p><strong>Later comment:</strong></p> <p>I've found that this works if I change from using Bind to:</p> <pre><code>DateTimeOffset='&lt;%# iif(IsDbNull(Eval("myDateTimeOffsetField")), Nothing, Eval("myDateTimeOffsetField")) %&gt;' </code></pre> <p>But then I don't get "myDateTimeOffsetField" passed as an argument in the FormView.ItemUpdating event (yes, this is in a FormView control) since ASP.NET assumes I'm not binding back to the Database.</p> <p><strong>Actual Code (Added by Request)</strong></p> <p>This is the Property in my Composite Control that I'm trying to bind to:</p> <pre><code>Public Property DateTimeOffset As DateTimeOffset? Get Return CType(ViewState("DTO"), DateTimeOffset?) End Get Set(value As DateTimeOffset?) ViewState("DTO") = value End Set End Property </code></pre> <p>Heres the markup for the Binding. The Control is in the EditItemTemplate of a FormView which is bound to a SQL DataSource returning a field called [dtoMldRejOn] with an optional DateTimeOffset value.</p> <pre><code>&lt;APS:DateTimeOffsetControl runat="server" id="dtocMldRejOn" TextBoxCssClass="inputdatetime" ValidationGroup="vw1" FieldName="&lt;%$ Resources: Resource, rxgFrom %&gt;" DateTimeOffset='&lt;%# Bind("dtoMldRejOn") %&gt;' WindowsTimeZoneID="&lt;%# me.WindowsTimeZoneID %&gt;" IsRequired="false" /&gt; </code></pre> <p>As you can see, my Composite control is for handling DateTimeOffset values. It all works great unless the DateTimeOffset field [dtoMldRejOn] from the database is NULL, then I get the exception.</p>
 

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