How to bind a Binding or a ValueConverter?

05-18-2009 7:29 AM |

I’m always struggling with ValueConverters because the ConvertParameter is not a dependency property and so it doesn’t support databinding.

I was trying to solve my problem by creating a derived ValueConverter with some extra properties. The ValueConverter is created in code (in a ViewModel class) and the extra properties are initialized.

Because I’m using the M-V-VM pattern I would like to bind the new converter to an existing binding or create a binding in run-time and bind it to a UI element. Something like this:

<dataControls:DataFormComboBoxField
   Binding="{Binding Id, Mode=TwoWay, Convert={Binding MyConverter}}"
</dataControls:DataFormComboBoxField>

Or

<dataControls:DataFormComboBoxField
   Binding="{Binding MyBindingWithConverter}"
</dataControls:DataFormComboBoxField>

Is there a way to bind a Binding or a ValueConverter in XAML? Can binding be used in static resources?

All tips and ideas are appreciated.

Stefan

Re: How to bind a Binding or a ValueConverter?

05-18-2009 9:06 AM |

Hi,

these articles can help you:

• Value converters - http://www.jeff.wilcox.name/2008/07/visibility-type-converter/
• Static resources - http://skysigal.xact-solutions.com/Blog/tabid/427/EntryId/799/Silverlight-DataBinding-to-a-static-resource.aspx

Re: How to bind a Binding or a ValueConverter?

05-19-2009 10:12 AM |

Thanks Davide.I know all the basics about binding, valueconverters and static resources, but I'm looking for a way to pass extra data to a value converter. So I was hoping that there would a way to bind a Binding object or a ValueConverter object.

e.g. a Binding object and a ValueConverter object are created in run-time and set in the code behind of the XAML file.

var myConverter = new ComboBoxLookupValueConverter(customers);
customerCombo.Binding.Converter = myConverter;

var myBinding = new Binding()
  {
    Source = customer,
    Path = new PropertyPath("CustomerId"),
    Converter = new ComboBoxLookupValueConverter(customers)
   };

customerCombo.Binding = myBinding ;

This works fine but I'm using a ViewModel so I would like to bind these objects via public properties. Something like

<dataControls:DataFormComboBoxField
   Binding="{Binding CustomerId, Mode=TwoWay, Converter={Binding MyConverter}}"
</dataControls:DataFormComboBoxField>

Or

<dataControls:DataFormComboBoxField
   Binding="{Binding MyBindingWithConverter}"
</dataControls:DataFormComboBoxField>

Is there a way to do this? Or could I use static resources and use bindings in these resources? Or has anyone created a derived Binding object which has dependency properties for extra parameters?

Re: How to bind a Binding or a ValueConverter?

05-19-2009 11:53 AM |

Anytime i need extra data in the value convertor, I use the converterparameter and pass an object in.

Re: How to bind a Binding or a ValueConverter?

05-19-2009 12:26 PM |

You can bind the object (rather than the individual values) and have the converter parse the needed values.

Re: How to bind a Binding or a ValueConverter?

05-27-2009 12:20 PM |

Have you downloaded Prism? http://compositewpf.codeplex.com/Release/ProjectReleases.aspx?ReleaseId=23450

After installed, you can find some examples in the "QuickStart" folder.