How to take extension arguments?

[steverice]

A bit confused on how an Ariadne extension is supposed to receive arguments upon instantiation.

There's an example of it in #608 with the trace_default_resolver argument, shown in the docs as being called like:

extensions=[ApolloTracingExtension(trace_default_resolver=True)]

When I try this however, I'm getting an error:

  File "/usr/local/lib/python3.7/dist-packages/ariadne/extensions.py", line 21, in __init__
    self.extensions = tuple(ext() for ext in extensions)
  File "/usr/local/lib/python3.7/dist-packages/ariadne/extensions.py", line 21, in <genexpr>
    self.extensions = tuple(ext() for ext in extensions)
TypeError: 'ApolloTracingExtension' object is not callable

Indeed, this error makes sense — although the ExtensionManager purports to take an ExtensionList (which can be an instance of an Extension as well as a class), it then immediately tries to call each extension. It also does not seem that Extension instances are expected to be callable.

It seems like I'm missing something, rather than this being a bug; especially as the code that calls extensions predates the implementation of that extension with an argument. So how is this supposed to work?

[rafalp]

You are not wrong, docs are incorrect here, because extension class is instantiated per query to let it store state. We should introduce utility functions for those like we do for query cost validator, that reduce partials keeping configuration from dev

[steverice]

Thanks @rafalp ! So would the suggestion for now be to use a partial?
I'm noticing now that I read the type of ExtensionList incorrectly — it indeed suggests that the extension must either be a class or a partial.