Example of auto generating type stubs

generate_typed_dicts.py

from datetime import datetime

STRING_DEFAULT = 'string'
DATETIME_DEFAULT = datetime(2015, 1, 1)
INT_DEFAULT = 123


def generate_typed_dicts(name, nested_dict):
    full_context = []
    final_dict = [f"class {name}(TypedDict):"]

    for k, v in nested_dict.items():
        if v == STRING_DEFAULT:
            v = str

        if v == DATETIME_DEFAULT:
            v = datetime

        if v == INT_DEFAULT:
            v = int

        if isinstance(v, dict):
            klass = k[0].upper() + k[1:]
            full_context.append(generate_typed_dicts(klass, v))
            final_dict.append(f"    {k}: {klass}")
        elif isinstance(v, str):
            final_dict.append(f"    {k}: str")
        elif isinstance(v, list):
            full_context.append(generate_typed_dicts(k, v[0]))
            final_dict.append(f"    {k}: List[{k}]")
        elif isinstance(v, (int, float)):
            final_dict.append(f"    {k}: {type(v).__name__}")
        # elif isinstance(v, str):  # forward reference
        #     final_dict.append(f"    {k}: '{k}'")
        else:  # class
            final_dict.append(f"    {k}: {v.__name__}")
    full_context.append('\n'.join(final_dict))

    return '\n\n\n'.join(full_context)


print(
    generate_typed_dicts(
        'S3PutEvent', {
            "Records": [{
                "eventVersion": "2.0",
                "eventTime": "1970-01-01T00:00:00.000Z",
                "requestParameters": {
                    "sourceIPAddress": "127.0.0.1"
                },
                "s3": {
                    "configurationId": "testConfigRule",
                    "object": {
                        "eTag": "0123456789abcdef0123456789abcdef",
                        "sequencer": "0A1B2C3D4E5F678901",
                        "key": "HappyFace.jpg",
                        "size": 1024
                    },
                    "bucket": {
                        "arn": "",
                        "name": "sourcebucket",
                        "ownerIdentity": {
                            "principalId": "EXAMPLE"
                        }
                    },
                    "s3SchemaVersion": "1.0"
                },
                "responseElements": {
                    "x-amz-id-2":
                    "EXAMPLE123/5678abcdefghijklambdaisawesome/mnopqrstuvwxyzABCDEFGH",
                    "x-amz-request-id":
                    "EXAMPLE123456789"
                },
                "awsRegion": "us-east-1",
                "eventName": "ObjectCreated:Put",
                "userIdentity": {
                    "principalId": "EXAMPLE"
                },
                "eventSource": "aws:s3"
            }]
        }))

s3_put_event_stub.py

class RequestParameters(TypedDict):
    sourceIPAddress: str


class Object(TypedDict):
    eTag: str
    sequencer: str
    key: str
    size: int


class OwnerIdentity(TypedDict):
    principalId: str


class Bucket(TypedDict):
    arn: str
    name: str
    ownerIdentity: OwnerIdentity


class S3(TypedDict):
    configurationId: str
    object: Object
    bucket: Bucket
    s3SchemaVersion: str


# note this requires manual fix :(
class ResponseElements(TypedDict):
    x-amz-id-2: str
    x-amz-request-id: str


class UserIdentity(TypedDict):
    principalId: str


class Records(TypedDict):
    eventVersion: str
    eventTime: str
    requestParameters: RequestParameters
    s3: S3
    responseElements: ResponseElements
    awsRegion: str
    eventName: str
    userIdentity: UserIdentity
    eventSource: str


class S3PutEvent(TypedDict):
    Records: List[Records]