I have a question about using `Parameter` in `ShellTask` Acc

Question

I have a question about using `Parameter` in `ShellTask` According to the docs `Parameter` is a type of `Task` and I m guessing it needs to get the method `run` called on it before it s usable I m guessing that this method is called when you pass the parameter to a function with the ` task` decorator I have a shell task which I d like to pass an object or a string which is created using a `Parameter` object Normally Shell tasks seem to be defined in the flow block When I try to run a shell task in a flow with arguments that are dependent on a parameter it fails with something like ```Traceback most recent call last File usr lib python3 8 runpy py line 193 in run module as main return run code code main globals None File usr lib python3 8 runpy py line 86 in run code exec code run globals File home macmenaminpe code prefect pdb flow parameterized flow py line 45 in lt module gt num lines = s task command=f wc l job pdb fp gt job job dir num lines txt File home macmenaminpe local lib python3 8 site packages prefect tasks core function py line 68 in getattr raise AttributeError f FunctionTask object has no attribute k AttributeError FunctionTask object has no attribute pdb fp``` So I guess the two questions are how do I get at the input val of a Parameter in a flow or do I not do this and always pass that param out to a ` task` and let it get handled there how do I create a shellTask that takes args

Chris White · Answer

Hi < Philip MacMenamin> you should treat Parameters like normal tasks So for example ```from prefect import task Parameter task def my parametrized task p print p with Flow example as flow param = Parameter p default=42 my parametrized task param flow run flow run p= new value ```

Chris White · Answer

For the shell task specifically I suggest customizing it to your needs via subclassing ```class MyTask ShellTask def run self custom param do stuff with custom param return super run kwargs pass whatever kwargs you want to the parent run method``` and then add this to your flow in the standard way

Philip MacMenamin · Answer

ok so for the first question you always pass the param to a task for it to be used You never use it within the flow block

Philip MacMenamin · Answer

And ok subclass out the shellTask class to call it with args Got it Thanks

Philip MacMenamin · Answer

`class MvTask ShellTask ` `def run self custom param ` ` do stuff with custom param` `return super run command = f util name custom param `

Chris White · Answer

yup that looks good to me

Philip MacMenamin · Answer

so if I wanted to pass a string to the shell task I set the command this way

Philip MacMenamin · Answer

ok thanks