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Struct __post_init__ is not called when converting to Struct with from_attributes=True #673
Description
Description
When using msgspec.convert() to convert to a Struct with from_attributes=True, the Struct's __post_init__ is not called. It works as expected with dataclasses.
from dataclasses import dataclass
import msgspec
@dataclass
class DataclassEgg:
grade: str
def __post_init__(self):
self.grade = f"dataclass({self.grade})"
class StructEgg(msgspec.Struct):
grade: str
def __post_init__(self):
self.grade = f"Struct({self.grade})">>> egg = {"grade": "A"}
>>> struct_egg = msgspec.convert(egg, StructEgg)
>>> struct_egg
StructEgg(grade='Struct(A)')
>>> dataclass_egg = msgspec.convert(egg, DataclassEgg)
>>> dataclass_egg
DataclassEgg(grade='dataclass(A)')
>>> msgspec.convert(struct_egg, DataclassEgg, from_attributes=True) # DataclassEgg post init is called
DataclassEgg(grade='dataclass(Struct(A))')
>>> msgspec.convert(dataclass_egg, StructEgg, from_attributes=True) # StructEgg post init is not called
StructEgg(grade='dataclass(A)')The last one should be:
StructEgg(grade='Struct(dataclass(A))')
Activity
jankotuc-brightpick commentedon Jun 13, 2024
@NCRonB I thought the same, but I found out the
__post_init__()is indeed being called. However, if there are any new fields defined in it (as in your example), these are silently ignored. To fix it, you have to create yourStructEggwith the configuration optiondict=True.If the
__post_init__()only contains validations or similar, there's probably no need for thedict=Trueoption.NCRonB commentedon Jun 14, 2024
@jankotuc-photoneo I'm not defining any new fields — only setting the one field
gradeto a different value. If you change the__post_init__()to simply print() something, you'll see that it doesn't print.I tried what you suggested, and it still doesn't work. If you have an example where it does, please share.