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Merged
merged 3 commits into from
Aug 12, 2022
Merged

Advanced type hinting support #102

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e61a1a6
Advanced type hinting support
cretz Aug 8, 2022
46f442d
3.7 fixes
cretz Aug 9, 2022
3bf2d33
Merge branch 'main' into type-hints
cretz Aug 11, 2022
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23 changes: 14 additions & 9 deletions README.md
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Expand Up @@ -187,15 +187,20 @@ The default data converter supports converting multiple types including:
* `None`
* `bytes`
* `google.protobuf.message.Message` - As JSON when encoding, but has ability to decode binary proto from other languages
* Anything that [`json.dump`](https://docs.python.org/3/library/json.html#json.dump) supports

As a special case in the default converter, [data classes](https://docs.python.org/3/library/dataclasses.html) are
automatically [converted to dictionaries](https://docs.python.org/3/library/dataclasses.html#dataclasses.asdict) before
encoding as JSON. Since Python is a dynamic language, when decoding via
[`json.load`](https://docs.python.org/3/library/json.html#json.load), the type is not known at runtime so, for example,
a JSON object will be a `dict`. As a special case, if the parameter type hint is a data class for a JSON payload, it is
decoded into an instance of that data class (properly recursing into child data classes). Currently this capability does
not extend to any other type hints that may wrap a data class like `Optional`, `List`, etc. This support is planned.
* Anything that can be converted to JSON including:
* Anything that [`json.dump`](https://docs.python.org/3/library/json.html#json.dump) supports natively
* [dataclasses](https://docs.python.org/3/library/dataclasses.html)
* Iterables including ones JSON dump may not support by default, e.g. `set`
* Any class with a `dict()` method and a static `parse_obj()` method, e.g.
[Pydantic models](https://pydantic-docs.helpmanual.io/usage/models)
* [IntEnum](https://docs.python.org/3/library/enum.html) based enumerates

For converting from JSON, the workflow/activity type hint is taken into account to convert to the proper type. Care has
been taken to support all common typings including `Optional`, `Union`, all forms of iterables and mappings, `NewType`,
etc in addition to the regular JSON values mentioned before.

Users are strongly encouraged to use a single `dataclass` for parameter and return types so fields with defaults can be
easily added without breaking compatibility.

### Workers

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