I have a form the gives me the following error when I try to design it in Visual Studio 2005:

It containsa custom control that exposes a generic list as apublic property.

The list is container for my custom type:

        [Serializable()]
        public class ListItem : IComparable, System.Runtime.Serialization.ISerializable
     {
            public int intId;
            public string Display;

            public ListItem()
            {
            }

            //Constructor for serialization
            protected ListItem(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context)
            {
                this.intId = info.GetInt32("intID");
                this.Display = info.GetString("Display");
            }
            public override string ToString()
            {
                return Display;
            }
            
            public static explicit operator ListItem(DataRowView Data)
            {
                ListItem Item = new ListItem();
                Item.intId = (int)Data.Row.ItemArray[0];
                Item.Display = (string)Data.Row.ItemArray[1];
                return Item;
            }

            #region IComparable Members

            public int CompareTo(object obj)
            {
                if (((ListItem)obj).intId == this.intId &&
                    ((ListItem)obj).Display.CompareTo(this.Display) == 0)
                    return 0;
                else
                    return this.Display.CompareTo(((ListItem)obj).Display);
            }

            #endregion


            #region ISerializable Members
            [System.Security.Permissions.SecurityPermission(
                System.Security.Permissions.SecurityAction.Demand,
                SerializationFormatter = false)]
            public void GetObjectData(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context)
            {
                info.AddValue("Display", this.Display);
                info.AddValue("intID", this.intId);
            }

I have been trying to figure this out for a while.

Any help on this problem will be greatly appreciated.

I am postingwhat I did to solve this problemin order that others who had the same problem will know what to do.

I deletedthe followinglines from .designer.cs file with a text editor.

this.kymMain.Events = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Events")));

this.kymMain.Keywords = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Keywords")));

this.kymMain.Programs = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Programs")));

I then added back the set accessors,deleted the user control dll, removed the refrences to it, saved the solution,closed Visual Studio, reopened it, rebuilt it, closed it again, reopened it andadded back the refrence. Now it appears in the designer properly.

Hello,

Is the assembly that contains your custom control strongly named? I am running into the same problem and it only occurred after I added a strong name to the assembly. I think I may know why too... Whenever I alter the class library that has the custom control then I have to manually remove all references to the control from other projects and readd it to get it to work and I think its because they are referencing the control from a library that no longer exists (since the version info changes) so it can't deserialize the Type needed. I think if you add the "Delay sign only" attribute to the library with your custom control then you can get around this while debugging, until you are ready to deploy. I"m not sure about this entirely but I think I'm on the right track here.

Try setting designerserializationvisibility on the List<> property. As in:

public class MyU : UserControl
{
private List<ListItem> myList = new List<ListItem>();

public MyU()
{
myList.Add(new ListItem(1,"1"));
myList.Add(new ListItem(2, "2"));
}

[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public List<ListItem> MyList
{
get { return myList; }
}
}

[Serializable()]
public class ListItem
{
public int intId;
public string Display;

public ListItem(int x, string y)
{
intId = x;
Display = y;
}
}

Which should result in code spit like:

this.myU1.MyList.Add(((WindowsApplication152.ListItem)(resources.GetObject("myU1.MyList"))));

this.myU1.MyList.Add(((WindowsApplication152.ListItem)(resources.GetObject("myU1.MyList1"))));

which hopefully will work better.

I added the [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
attribute to the properties and it still does not appear in the designer.

this.kymMain.Events = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Events")));

this.kymMain.Keywords = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Keywords")));

this.kymMain.Location = new System.Drawing.Point(3, 66);

this.kymMain.Name = "kymMain";

this.kymMain.People = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.People")));

this.kymMain.Programs = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Programs")));

It looks like you may not have added the attribute correctly. Can you try my sample to see if it works correctly?

Remember to remove the "set" property accessor from your properties as well.

I tried using your sample and it still did not affect the code that was already in the designer.cs file.

I also took off the set accessors, temporarily, as I will need set accessors. However, it still did not affect the code.

Thanks for your effort so far.

Have you tried to open the form and modify it to force a new serialization to occur?

If you can try it on a new form to ensure it works, then the problem is only updating older forms.

Also, if you can do a full rebuild -- then close and reopen VS2005, that may also fix the issue. Sorry for this problem.

I am postingwhat I did to solve this problemin order that others who had the same problem will know what to do.

I deletedthe followinglines from .designer.cs file with a text editor.

this.kymMain.Events = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Events")));

this.kymMain.Keywords = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Keywords")));

this.kymMain.Programs = ((System.Collections.Generic.List<fcPhotoGallUpload.keywordManeger.ListItem>)(resources.GetObject("kymMain.Programs")));

I then added back the set accessors,deleted the user control dll, removed the refrences to it, saved the solution,closed Visual Studio, reopened it, rebuilt it, closed it again, reopened it andadded back the refrence. Now it appears in the designer properly.

Hello,

Is the assembly that contains your custom control strongly named? I am running into the same problem and it only occurred after I added a strong name to the assembly. I think I may know why too... Whenever I alter the class library that has the custom control then I have to manually remove all references to the control from other projects and readd it to get it to work and I think its because they are referencing the control from a library that no longer exists (since the version info changes) so it can't deserialize the Type needed. I think if you add the "Delay sign only" attribute to the library with your custom control then you can get around this while debugging, until you are ready to deploy. I"m not sure about this entirely but I think I'm on the right track here.

This is not a dependable solution because next time you add another instance of that control to the page, it happens again.

Here is my code :

[LookupBindingProperties("DataSource", "DisplayMember", "ValueMember", "SelectedValue")]
public partial class BaseLookupControl : BaseUserControl
{
public BaseLookupControl()
{
InitializeComponent();
}

private string myDisplayMember;
[DefaultValue("")]
public string DisplayMember
{
get { return myDisplayMember; }
set
{
myDisplayMember = value;
OnDisplayMemberChanged(new EventArgs());
}
}

public event EventHandler DisplayMemberChanged;

protected virtual void OnDisplayMemberChanged(EventArgs e)
{
if (DisplayMemberChanged != null)
{
DisplayMemberChanged(this, e);
}
}

private string myValueMember;
[DefaultValue("")]
public string ValueMember
{
get { return myValueMember; }
set
{
myValueMember = value;
OnValueMemberChanged(new EventArgs());
}
}

public event EventHandler ValueMemberChanged;

protected virtual void OnValueMemberChanged(EventArgs e)
{
if (ValueMemberChanged != null)
{
ValueMemberChanged(this, e);
}
}

private object myDataSource;
[DefaultValue("")]
[AttributeProvider(typeof(IListSource))]
[RefreshProperties(RefreshProperties.All)]
public object DataSource
{
get { return myDataSource; }
set
{
myDataSource = value;
OnDataSourceChanged(new EventArgs());
}
}

public event EventHandler DataSourceChanged;

protected virtual void OnDataSourceChanged(EventArgs e)
{
if (DataSourceChanged != null)
{
DataSourceChanged(this, e);
}
}

private string myDataMember;

[RefreshProperties(RefreshProperties.All)]
[Editor("System.Windows.Forms.Design.DataMemberListEditor, System.Design", "System.Drawing.Design.UITypeEditor, System.Drawing")]
[DefaultValue("")]
public string DataMember
{
get { return myDataMember; }
set
{
myDataMember = value;
OnDataMemberChanged(new EventArgs());
}
}

public event EventHandler DataMemberChanged;

protected virtual void OnDataMemberChanged(EventArgs e)
{
if (DataMemberChanged != null)
{
DataMemberChanged(this, e);
}
}

private string mySelectedValue;
public event EventHandler SelectedValueChanged;

[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
[Browsable(false)]
[Bindable(true)]
[DefaultValue("")]
public string SelectedValue
{
get { return mySelectedValue; }
set
{
mySelectedValue = value;
OnSelectedValueChanged(new EventArgs());
}
}

protected virtual void OnSelectedValueChanged(EventArgs e)
{
if (SelectedValueChanged !=null)
{
SelectedValueChanged(this, e);
}
}

private void BaseLookupControl_Load(object sender, EventArgs e)
{
}

}

I have copied most of it from the Meta information of "LISTBOX" control.

Listbox does not have "DesignerSerializationVisibility.Hidden" or "DesignerSerializationVisibility.Content" attribute on the Datasource property.

However, when I drop this control on my form I get "DataSource of controlxyz is null. This is not allowed" error message (Yes, a popup error message on the designer).

Even if I set the DataSource of this control to a dataset on my form, that error keeps popping up.

If I add an attribute "DesignerSerializationVisibility.Content" or "DesignerSerializationVisibility.Hidden", then the designer does not gererate code in the designer file. I tried BOTH of the settings, yields the same result. I was expecting it to WRITE CODE i nthe designer file with the "CONTENT" setting, but not serialize it in the resX file...

Can you please give a clear description of the designer serialization attribute values, and the designer.cs (or vb for that matter) and resx behavior ?

Please correct me if I am wrong: on http://msdn2.microsoft.com/en-us/library/system.componentmodel.designerserializationvisibility.aspxit says

	Member name	Description
	Content	The code generator produces code for the contents of the object, rather than for the object itself.
	Hidden	The code generator does not produce code for the object.
	Visible	The code generator produces code for the object.

There is NOTHING about the serialization in the resX file there...

But I assume "rather than the object itself" means "the object will not be serialized in the RESX file" there.

Please suggest

My assemblies are also strongly named, but my base control and the derived controls are in the same library, i moved them together, still no luck...

Try to write designer for your control like that:

class YourControlDesigner : System.Windows.Forms.Design.ControlDesigner
{
public YourControlDesigner()
{ }

protected override void PostFilterProperties(System.Collections.IDictionary properties)
{
properties.Remove("YourGenegicPropertyName");
}
}

And You should type that code before declaration of your control

[Designer(typeof(YourControlDesigner))]
public partial class YourControl : UserControl
{
}

It works for me, may be one helps you.

ANSWER:

All you have to do is justdelete the .resx file for the form that the custom control resides on. Re-open the form in the designer and make your changes and re-compile. Sometimes the problem goes away and sometime it comes back.

-ratster