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We are re-hosting the WF-4 designer in our own app. We have something called a Filter. Now we want an activity that lets you run this filter and work with the results in a ForEach. Simple enough. But these Filters have a list of parameters (for running the filter) that need to be filled in the workflow host. The list of filter parameters can be anything from 0 to N.

After the user sets FilterId, is there a way we can create an instance of that Filter, examine its list of parameters and add those parameters to the Activity? The parameters are basically just Name, Type and needs its Value filled out by the user.

Another thing, we do not want to create an instance of the Filter at run-time, that would be too expensive. At run-time, we just need the filter id and the list of parameter Values.

I'd be happy with having a static property for parameters, if there is a way to update it when FilterId changes and validate that all parameters in this list have values.

Robert Harvey
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Robert Jeppesen
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1 Answers1

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I haven't done this myself but if I am not mistaken I have seen other people do something like this by implementing the ICustomTypeDescriptor interface. And that is what the Interop activity uses to display the properties of the WF3 activity as WF4 InArgument/OutArguments.

Maurice
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