Hello everyone, I’m trying to have an oriented app...
# prefect-community
Hello everyone, I’m trying to have an oriented approach to Flows and Tasks. The idea is to inherit specific flow types that already have some methods as tasks. Only overriding them if necessary. I realize that the decorator
doesn’t seem to work for class properties. Here is the error:
Copy code
File "/Users/nuno/Developer/Data-Framework/data-prefect/data_prefect/utils/flows.py", line 67, in factory_flow
  File "/Users/nuno/Developer/Data-Framework/data-prefect/.venv/lib/python3.8/site-packages/prefect/core/task.py", line 470, in __call__
  File "/Users/nuno/Developer/Data-Framework/data-prefect/.venv/lib/python3.8/site-packages/prefect/core/task.py", line 511, in bind
    callargs = dict(signature.bind(*args, **kwargs).arguments)  # type: Dict
  File "/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/lib/python3.8/inspect.py", line 3025, in bind
    return self._bind(args, kwargs)
  File "/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/lib/python3.8/inspect.py", line 2940, in _bind
    raise TypeError(msg) from None
TypeError: missing a required argument: 'self'
It seems that I cannot pass the method “self” argument. Do you guys have any suggestion? Thank you in advance.
Hey @Nuno, I believe you are looking for a more object-oriented approach using the imperative API to subclass the base
class (or any task class for that matter) and not
. In that case, we'd need to from
prefect import Task
instead of
. I think this is a good example of subclassing capital T-ask and creating custom tasks in that way.
Thanks Kyle. Yes, actually I had already seen that tutorial, and I came the conclusion that it would be best to follow that approach instead of trying to re-invent the wheel. It almost the same thing that I wanted to do, the difference is that I’m creating classes on the task level instead of the flow Level, and having the tasks available as properties methods. I think it would be nice though, to see if this last approach would be good to use. The advantage, in my opinion, is less boilerplate code.
Ah I see, you want to subclass Flow in some respect with a set of built-in tasks and add tasks/dependencies as needed? I haven't seen an example of that yet! Others have certainly passed a set of custom tasks between their flows, but I imagine using a Flow with property tasks could make setting up dependencies slightly more difficult.
If you get something working, we'd love to see it and share with others!
For now, I’ve took the approach already available in the prefect docs. But If I look into it again, and see how to it, I’ll share with everyone here, for sure. Thanks for the feedback 🙂
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