Recursive definition about nvelope HOT 4 CLOSED

@donpatrice The only way to do it is some monkey-patching.
For python 3.8 it would be:

from __future__ import annotations

from dataclasses import dataclass
from typing import List

from nvelope import Obj, string_conv, ListConversion, CompoundConv


@dataclass
class Section(Obj):
    _conversion = {"title": string_conv}

    title: str
    sections: MaybeMissing[List[Section]]


Section._conversion["sections"] = ListConversion(CompoundConv(Section))

You may want to use the latest version 0.3.1 with better support for string type annotations (namely, MaybeMissing logic).

from nvelope.

Thank you so much for the quick reply and the nice work. There is one little question left. If I now have an JSON with an array of sections I would do something like:

class Sections(Arr):
    conversion = Compound(Section)

sections = Sections.from_json(json_file)

right?
And then I can do:

foo = Section.from_json(
    {
        "title": "bar",
        "sections": Sections.from_json(json_file).as_json()
    }    
)

Is that the way how I do it properly? Or can I somehow "directly" assign the list of sections to foo?

Thanks a lot!

from nvelope.

@donpatrice if I get you right, you might wanna do something like this:

foo = Section.from_json({"title": "bar"})
foo.sections = Jst(list(sections))    # use Jst wrapper since we defined sections as MaybeMissing attribute

Sections you defined here is neither an equivalent of List[Sections] nor is it an equivalent of MaybeMissing[List[Sections]], so your second block of code is not the way to go.

However, it seems to me that you don't need to define the Sections class to do what you are describing here. It can be done much simpler this way:

foo = Section.from_json(
     {
          "title": "bar",
          "sections": json_file 
     }
)

or

foo = Section(
    title="bar",
    sections=Jst([Section.from_json(record) for record in json_file])
)

Note: in the first code block you used wrong class. It must be CompoundConv instead of Compound

from nvelope.

Thanks a lot @monomonedula, both for your help and the great work!

Note: in the first code block you used wrong class. It must be CompoundConv instead of Compound

Yes you are right, that was a typo.

from nvelope.