metadocuments 1.4.1

Library for defining structured documents (JSON, YAML) as classes. Created as a metaprogramming exercise

MetaDocuments

Installation

pip install metadocuments

Usage

Decorate the document with @Metadocument to specify that it (and all its children) should be treated as a metadocument. This adds functions to_dict, to_json and to_yaml to the class instance which then can be called to create a corresponding structure. Classes can contain methods, but those are ignored unless they are decorated with @property. Inheritance and multiple inheritance do work, the @Metadocument decorator is only required for the parent class.

Example

@MetaDocument
class SubObject:
    a = 2
    b = "c"

@Metadocument
class MyClass:
    a = 1
    b = SubObject()

print(MyClass().to_json(indent=4))
# {
#     "a": 1,
#     "b": {
#         "a": 2,
#         "b": "c"
#     }
# }

Example 2

@Metadocument
class MyClass:
    a = 1

class Child(MyClass):
    b = 2
    c = "c"

print(Child().to_json(indent=4))
# {
#     "a": 1,
#     "b": 2,
#     "c": "c"
# }

Example 3

Using FromKeywords helper class. This can be helpful when there are structures that one does not want to define as class. All the keywords are mapped 1:1 to a attribute / key.

if __name__ == "__main__":
    @Metadocument
    class Foobar():
        a = 1
        b = Field(key="v-1", value="somevalue")
        c = FromKeywords(
            d="a",
            e="b",
            f=FromKeywords(
                g=1,
                asd=FromKeywords(
                    a = "b"
                )
            )
        )
    print(Foobar().to_json(indent=4))

Limitations

Because of Python syntax abuse, there is no support for numeric keys unfortunately. If those are necessity, then old-school dicts are best option (for now).

FromKeywords does inherit dict so it is possible to use it inside a dictionary which then can be serialized to JSON.

if __name__ == "__main__":
    @Metadocument
    class Foobar:
        a = 1
        b = 2
        c = FromKeywords(
            d="a",
            e="b",
            f=FromKeywords(
                g=1,
                asd=FromKeywords(
                    a = "b"
                )
            )
        )

    some_dict = {
        "foo": "bar",
        1: "asd",
        "afgg": FromKeywords(
            a=1, b=2
        ),
        "ccc": Foobar().to_dict()
    }
    print(Foobar().to_json(indent=4))
    print(json.dumps(some_dict))