.NET Tips and Tricks

Blog archive

Connecting One WebPart to Many in SharePoint

Given the number of default interfaces that SharePoint provides, it's conceivable that you might want to create a provider WebPart that several consumers could connect to simultaneously. To make that happen, you must specify in the connection method that multiple consumers are allowed.

After decorating your connection method with the ConnectionProvider attribute, set the attribute's AllowsMultipleConnections property to True. Here's an example of a connection method for a provider that supports the IWebPartTable interface:

<ConnectionProvider("First Name", _
       AllowsMultipleConnections:=True)> _
Public Function MyProviderMethod() As IMyWebPartTable
  Return Me
End Function

A provider with a ConnectionProvider method like this could drive several consumer WebParts on the same page. You can also mark a ConnectionConsumer as allowing multiple connections which would allow a single consumer to interact with several providers at once (that would, I think, be something of a nightmare).

If you want a consumer WebPart to be able to connect to WebParts that support different interfaces (a consumer WebPart that works with both the IWebPartRow and IWebPartTable interfaces, for instance) then you need two separate connection methods: one for each interface. The same is true if you want to create provider that provides data through two or more interfaces (both the IWebPartRow and IWebPartParameters interfaces, for instance).

When you have multiple connection methods in the same WebPart, you must assign each method a unique id as the second parameter to the method's Connection* attribute. That's what this example does, creating a consumer that can work with both the IWebPartTable and IWebPartRow interfaces:

<ConnectionConsumer("Employee Data", "AllData")> _
Public Sub MyConsumerMethodForAllData(parm As IWebPartTable)
  '…code
End Sub
<ConnectionConsumer("Employee Data", "SelectedRow")> _
Public Sub MyConsumerMethodForSelectedRow(parm As IWebPartRow)
  '…code
End Sub

However, there are two scenarios related to these examples that aren't supported: A WebPart cannot connect multiple times to the same WebPart; if you have two WebParts that both support both the IWebPartTable and the IWebPartField interfaces (one as a consumer and one as a provider), they can only be connected once. The user will decide at runtime which interface to use.

Also, users can't connect a provider to a consumer that it's already connected to even if they swap roles. You can't, for instance, connect a WebPart A as a consumer to WebPart B as a provider, then turn around and have WebPart B connect as a consumer to WebPart A as a provider.

Posted by Peter Vogel on 12/10/2012 at 1:16 PM


comments powered by Disqus

Featured

  • Python in VS Code Adds Data Viewer for Debugging

    The January 2021 update to the Python Extension for Visual Studio Code is out with a short list of new features headed by a data viewer used while debugging.

  • GitHub Ships Enterprise Server 3.0 Release Candidate

    It's described as "the biggest ever change to Enterprise Server," with improvements to Actions, Packages, mobile, security and more.

  • Attacks on .NET Apps Grow in Number, Severity, Says Security Firm

    .NET apps were found to have more serious vulnerabilities and suffer more attacks last year, according to data gathered by Contrast Labs.

  • Microsoft Opens Up Old Win32 APIs to C# and Rust, More Languages to Come

    Microsoft is opening up old Win32 APIs long used for 32-bit Windows programming, letting coders use languages of their choice instead of the default C/C++ option.

Upcoming Events