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POBinding to a Nullable<DateTime> control property
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  1. POBinding to a Nullable<DateTime> control property
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    copied!<p>We have a custom control that has a "Value" property of type System.Nullable (aka System.DateTime?). We have an object with a "Received" property of the same type. When we try to bind the control to the object, the following <em>InvalidCastException</em> is thrown:</p> <p><strong>Invalid cast from 'System.DateTime' to 'System.Nullable`1[[System.DateTime, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]'.</strong></p> <p>Here is what we're doing:</p> <p>Object property:</p> <pre><code>private System.DateTime? _dateTimeReceived; public System.DateTime? DateTimeReceived { get { return this._dateTimeReceived; } set { this._dateTimeReceived = value; this.OnChanged("DateTimeReceived", value); //Implements INotifyPropertyChanged and fires PropertyChanged event } } </code></pre> <p>Control property:</p> <pre><code>private System.DateTime? _value; [System.ComponentModel.Category("Behavior")] [System.ComponentModel.Description("The current date value for this control")] public new System.DateTime? Value { get { return this._value; } set { this._value = value; } } </code></pre> <p>In the application, here is where the exception is thrown:</p> <pre><code>this.dateReceived.DataBindings.Add("Value", this._object, "DateTimeReceived"); </code></pre> <p>As you can see, the object's property (this._object.DateTimeReceived) is a System.DateTime? type and the control's property (this.dateReceived.Value) is a System.DateTime? type.</p> <p>Why would this cause an <em>InvalidCastException</em>? And how can we correct this so that it binds correctly?</p> <p><strong>Update 2009-10-29 14:26 CDT:</strong></p> <p>Here is the stack trace:</p> <blockquote> <p>at System.Convert.DefaultToType(IConvertible value, Type targetType, IFormatProvider provider)<br> at System.DateTime.System.IConvertible.ToType(Type type, IFormatProvider provider) <br> at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider) <br> at System.Windows.Forms.Binding.FormatObject(Object value)<br> at System.Windows.Forms.Binding.PushData(Boolean force) <br> at System.Windows.Forms.Binding.UpdateIsBinding() <br> at System.Windows.Forms.Binding.CheckBinding() <br> at System.Windows.Forms.Binding.SetListManager(BindingManagerBase bindingManagerBase) <br> at System.Windows.Forms.ListManagerBindingsCollection.AddCore(Binding dataBinding) <br> at System.Windows.Forms.BindingsCollection.Add(Binding binding) <br> at System.Windows.Forms.BindingContext.UpdateBinding(BindingContext newBindingContext, Binding binding)<br> at System.Windows.Forms.Binding.SetBindableComponent(IBindableComponent value)<br> at System.Windows.Forms.ControlBindingsCollection.AddCore(Binding dataBinding) <br> at System.Windows.Forms.BindingsCollection.Add(Binding binding) <br> at System.Windows.Forms.ControlBindingsCollection.Add(String propertyName, Object dataSource, String dataMember, Boolean formattingEnabled, DataSourceUpdateMode updateMode, Object nullValue, String formatString, IFormatProvider formatInfo) <br> at System.Windows.Forms.ControlBindingsCollection.Add(String propertyName, Object dataSource, String dataMember)<br></p> </blockquote>
 

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