Hello,

I'm recieving the following error message below. Basically I have 2 WebParts. The first WebPart has a dropdown that display items when you select an item from the dropdown then It should populate the details within WebPart 2 inside of a GridView. Please see my .ASPX page below to make sure I'm not missing something. Thanks in advance!!

The provider (webpart with dropdownlist) need to have a method that has the ConnectionProvider-attribute and returns an interface with the data.
The consumer (webpart with gridview) need to have an entry-point by specifying a method with the ConnectionConsumer-attribute. Both attributes needs to have the same name in their parameters.
This allows the WebPartManager to know to send what data from where to where. Without these methods, your WebParts won't be recognized as "connectable" parts ;)

I hope this article will give you an overview of WebPart connections: http://msdn.microsoft.com/msdnmag/issues/06/02/BasicInstincts/

The aspx code seems ok

Please let me know if my Provider and Consumber connections look okay.

<%@ Implements Interface="IField" %>

<script runat="server">

Get

End Get

<ConnectionProvider("Message")> _

Return Me

</script>

Sub SetMessage(ByVal message As IField)

End Sub

</script>

Yes, this seems to be ok. and implementing it quickly in a demo it works for me as well ;)

See it works for me with one WebPart but does not populate the other WebPart :(

I created a usercontrol to populate data to a dropdownlist control within WebPart one. I would like to pass the value which is an integer from the dropdown to the second WebPart which is a GridView Control. I can't figure this out for the life of me. Any help would be greatly appreciated

Thanks in advance!!

You are missing probably the OnPreRender method where you actually performs the binding of your gridview with the received data.

The binding has to be done "OnPreRender" because earlier in the page lifecycle you are never sure if already received the data or not. 
Try adding next method in your consumer web part

    Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)
        ReceivedData As Integer = Me._message.Message
        ' bind the gridview
        MyBase.OnPreRender(e)
    End Sub

 sorry if the syntax is wrong. I don't know much VB :S

You also need to have PostBack = True on your DropDownList so that a postback is performed when you change the dropdownlist.

Still having trouble populating the data from the dropdownlist. Please see my interface code below to make sure I have it setup correctly. Also, what should I have to "RecievedData" it tells me that it's not defined.

<%@ Implements Interface="IField" %>
<script runat="server">
Public ReadOnly Property Message() As Integer _
Implements IField.Message
Get
Return subnetsList.SelectedValue
End Get
End Property
<ConnectionProvider("Message")> _
Public Function GetMessage() As IField
Return Me
End Function
</script>

SelectedValue is a string, so when probably should cast it to an integer first in the property. unless you have your Message declared as string in your interface. then you will have to cast it to an integer when you bind it to the SelectedIndex.

Still no dice. The value that I'm trying to retrieve is an "integer". I applied the code that you provided and I do not recieve any errors except that it does not retrieve the data into the second webpart. Can you give me an idea as to how i should cast it as an integer and where. Sorry still learning. Thanks a million for all of your help.

I need help with the interface connection.

Please Help!! Very desperate.