Getting init() missing required positional arguments when using a dataclass

Question

I know the init method is built automatically when creating a dataclass, but when I try this definition:

@dataclass
class LayoutCollection:
    root_folder_idx: dict = field(repr=False)
    folder_idx: dict = field(repr=False)
    layouts: List[Layout] = field(default_factory=list)

    def __post_init__(self):
        if len(self.folder_idx) == 0:
            self._populate_folder_index()
            self._populate_root_folder_index()
    
    def __repr__(self):
        return json.dumps(self.__dict__)

Anytime I run this code I get:

TypeError: __init__() missing 2 required positional arguments: 'root_folder_idx' and 'folder_idx'

If I re-order the arguments such that the layouts: attribute is first, I get:

TypeError: non-default argument 'root_folder_idx' follows default argument

I'm just trying to make it so that layouts initializes as a list of Layout objects, while the other two initialize as dict() but aren't represented during repr

Jorvis · Accepted Answer · 2022-08-17 04:08:07Z

2

Of course, right when I ask I figure it out.

On both of the attributes I wanted to initialize as dictionaries I needed to add default_factory defs, like this:

root_folder_idx: dict = field(default_factory=dict, repr=False)

answered Aug 17, 2022 at 4:08

Jorvis

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1 Comment

Dr Nisha Arora Over a year ago

It's good that you figured it out. However, it is always suggested to ask such questions with the code that can be reproduced so that others can try that out and answer

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