Dictionary to dataclasses with inheritance of classes

问题

I have the following class

@dataclass_json
@dataclass
class Input:
    sources: List[Sources] =None
    Transformations: List[str] =None

As well as:

@dataclass_json
@dataclass
class Source:
    type: str =None
    label: str =None
    path: str = None

and the two subclasses:

@dataclass_json
@dataclass
class Csv(Source):
    csv_path: str=None
    delimiter: str=';'

and

@dataclass_json
@dataclass
class Parquet(Source):
    parquet_path: str=None

Given now the dictionary:

parquet={type: 'Parquet', label: 'events', path: '/.../test.parquet', parquet_path: '../../result.parquet'}

csv={type: 'Csv', label: 'events', path: '/.../test.csv', csv_path: '../../result.csv', delimiter:','}

input={'sources':[csv, parquet]}

Now I would like to do something like

Input().from_dict(input) 

with Output:

Input(sources: [Parquet(...), Csv(...)]).

This actually works but it just returns the values of the 3 paremeters from dataclass Source (type, label and path) and not the other specific parameters of Csv and Parquet (csv_path, delimiter and parquet_path), which are just given its default value. This may be due to the library dataclass_json taken the schema of a class before initializing it. On the other hand, I would like to make still use of dataclass_json and just make a wrapper since it has good case and error handling.

I want this behaviour since each source type has different arguments which defines itself (for example Csv has delimiters but Parquet does not, etc. ...).

I struggled trying to obtain the class Source and find the subclasses in the library dataclass_json. Doing so, I encountered

cls.__args__[0]

which is of type 'GenericMeta'. But given this, I could not obtain access to its subclasses.

Is there any work around?

I am using Python 3.6, by the way.

Thanks in advance for your help.

来源：https://stackoverflow.com/questions/61541259/dictionary-to-dataclasses-with-inheritance-of-classes