Wrapping activity inputs and outputs
The implementation of the Workflow Runtime uses mechanisms to internally stay agnostic of used APIs. To achieve this, all non-builtin types in the output of an activity should get wrapped in a WrapperBase
:
public Task<IDictionary<string, object>> Execute(IDictionary<string, object> inputs, IActivityContext context)
{
// activity work, e.g. creating a feature
IDictionary<string, object> outputs = new Dictionary<string, object>();
outputs.Add("feature", new CustomActivityWrapper(createdFeature));
return Task.FromResult(outputs);
}
where an implementation of a WrapperBase at least offers a Unwrap
method:
private class CustomActivityWrapper : WrapperBase
{
//internals of the wrapper
public override object Unwrap()
{
return _actualObject;
}
}
Unwrapping inputs
Thus all inputs in an activity should get unwrapped before working with it. On Studio Desktop you may cast the input either to WrapperBase
or IServiceProvider
- both methods are equivalent:
public Task<IDictionary<string, object>> Execute(IDictionary<string, object> inputs, IActivityContext context)
{
// Variant 1 IServiceProvider:
IServiceProvider provider = inputs["feature"] as IServiceProvider;
Row actualObject = (Row)provider.GetService(typeof(Row));
// Variant 2 WrapperBase:
WrapperBase wrapper = inputs["feature"] as WrapperBase;
Row actualObject2 = (Row)wrapper.Unwrap();
}