Converting all Structs (including nested ones) to dict. #594

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1. zulqasar commented on Nov 27, 2023

   

   zulqasar

   on Nov 27, 2023

   Author

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   Currently I am using this fix.

   import msgspec
   
   class Dog(msgspec.Struct):
       name: str
       age: int
   
   class Owner(msgspec.Struct):
       name: str
       dogs: list[Dog]
   
   owner = Owner('A dog owner', [Dog('Doggie', 2)])
   
   msgspec.structs.asdict(owner)
   # >> {'name': 'A dog owner', 'dogs': [Dog(name='Doggie', age=2)]}
   
   # Fix
   encoder = msgspec.json.Encoder()
   decoder = msgspec.json.Decoder()
   
   decoder.decode(encoder.encode(owner))
   #>> {'name': 'A dog owner', 'dogs': [{'name': 'Doggie', 'age': 2}]}
2. jcrist commented on Nov 28, 2023

   

   jcrist

   on Nov 28, 2023

   Member

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   Am I missing out something?

   msgspec.structs.asdict doesn't recurse into struct fields when converting structs to dicts, it only applies to the top-level struct.

   To recurse through all fields, lowering complex types like structs/dataclasses/attrs/... to simpler types like int/str/dict/... you'll want to use msgspec.to_builtins. This is effectively the same as msgspec.json.decode(msgspec.json.encode(obj)), but is much more efficient.

   See docs here and here.

   In [2]: import msgspec
      ...: 
      ...: class Dog(msgspec.Struct):
      ...:     name: str
      ...:     age: int
      ...: 
      ...: class Owner(msgspec.Struct):
      ...:     name: str
      ...:     dogs: list[Dog]
      ...: 
      ...: owner = Owner('A dog owner', [Dog('Doggie', 2)])
   
   In [3]: msgspec.to_builtins(owner)
   Out[3]: {'name': 'A dog owner', 'dogs': [{'name': 'Doggie', 'age': 2}]}

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3. jcrist

   closed this as completedon Nov 28, 2023