Bug: Python binding creation of big JSON data mutates in deeply nested values

[humrochagf]

Ladybug version

v0.15.1

What operating system are you using?

Arch Linux

What happened?

Hey, I continued my tests on storing big json objects into the database and noticed that an unwanted mutation of some dict values is happening in deeply nested json.

Are there known steps to reproduce?

To reproduce it make sure you have the following libs installed for better visualization of the result:

pytest==9.0.2
pytest-icdiff==0.9
real_ladybug==0.15.1

Then put this code in a bug.py file:

import json

from real_ladybug import Connection, Database

def test_nested_json():
    db = Database("database.lbug")

    conn = Connection(db)
    conn.execute(
        """
        INSTALL json;
        LOAD json;
        CREATE NODE TABLE IF NOT EXISTS User
        (id SERIAL PRIMARY KEY, meta JSON);
        """
    )

    data = {
        "id": "http://localhost:8000/actors/testuser",
        "ap_data": {
            "id": "http://localhost:8000/actors/testuser",
            "type": "Person",
            "name": "",
            "summary": "",
            "username": "testuser",
            "inbox": "http://localhost:8000/actors/testuser/inbox",
            "outbox": "http://localhost:8000/actors/testuser/outbox",
            "public_key": {
                "id": "http://localhost:8000/actors/testuser#main-key",
                "owner": "http://localhost:8000/actors/testuser",
                "public_key_pem": (
                    "-----BEGIN PUBLIC KEY-----\n"
                    "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAni2p5Ni2mVmHKFlOFA5w\n"
                    "zBLTZS3cEdiQ/IBqeSKYcKU4TFEhaFaVy3Be4pL+vFwX+iEXpvAznEhaC6oTU2zC\n"
                    "EaXFhmVInsZ3kzrz2vTeXsOIwJ4auR8fFziwewXYXUgT0/KmSlNaYMz1PbXxPS+P\n"
                    "DHL7E6ovJSau8Hj7UMDpF6W0Xty8PoU/Kw9Fyt3SXBHz6h5hvNXTiqS2HxWDbtz/\n"
                    "j5tZlpvxiZ/sFN2w/bsotlbe2QOF5HuLA/w7B3E1Tan8jLNO4qXEHffdUZEl92ad\n"
                    "dqnhsH9MJbRp6YfNnRMd1NaHu+rDUjTur34r5oVEz766oU/ZnGlGpJsvaQmUiMW8\n"
                    "XQIDAQAB\n"
                    "-----END PUBLIC KEY-----\n"
                ),
            },
            "manually_approve_followers": False,
            "@context": [
                "https://www.w3.org/ns/activitystreams",
                "https://w3id.org/security/v1",
                {"manuallyApprovesFollowers": "as:manuallyApprovesFollowers"},
            ],
        },
        "is_local": True,
        "created_at": "2026-02-25T00:54:29.987623Z",
    }


    response = conn.execute(
        """
        CREATE (n:User {meta: to_json($meta)})
        RETURN n.id as id, cast(n.meta AS STRING) as meta;
        """,
        parameters={
            "meta": data,
        },
    )

    response_data = json.loads(response.rows_as_dict().get_all()[0]["meta"])

    assert response_data == data

Then you can run the following:

pytest -vv bug.py

You should get this output error:

[aheev]

seems like each element in the array is parsed as another nested JSON object

[humrochagf]

I'll try some things but my guess is that it assumes that all members of the array should be structs based in one of its members

[humrochagf]

Yup, it's the array, I tried with this data and it also reproduces:

    data = {
        "test_array": [
            "test_string_array",
            {"test_object_key": "test_object_value"},
        ],
    }

And if you try to add something that would not fit in the object like this:

    data = {
        "test_array": [
            "test_string_array",
            False,
            {"test_object_key": "test_object_value"},
        ],
    }

It gets an error that explicits more the issue:

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <real_ladybug.prepared_statement.PreparedStatement object at 0x7f93a6717230>, connection = <real_ladybug.connection.Connection object at 0x7f93a67170e0>
query = '\n        CREATE (n:User {meta: to_json($meta)})\n        RETURN n.id as id, cast(n.meta AS STRING) as meta;\n        '
parameters = {'meta': {'test_array': ['test_string_array', False, {'test_object_key': 'test_object_value'}]}}

    def __init__(self, connection: Connection, query: str, parameters: dict[str, Any] | None = None):
        """
        Parameters
        ----------
        connection : Connection
            Connection to a database.
        query : str
            Query to prepare.
        parameters : dict[str, Any]
            Parameters for the query.
        """
        if parameters is None:
            parameters = {}
>       self._prepared_statement = connection._connection.prepare(query, parameters)
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
E       RuntimeError: Runtime exception: Cannot convert Python object to Lbug value : BOOL  is incompatible with STRUCT(test_object_key STRING)

.venv/lib/python3.14/site-packages/real_ladybug/prepared_statement.py:28: RuntimeError
============================================================================================= short test summary info ==============================================================================================
FAILED bug.py::test_nested_json - RuntimeError: Runtime exception: Cannot convert Python object to Lbug value : BOOL  is incompatible with STRUCT(test_object_key STRING)
================================================================================================ 1 failed in 0.10s =================================================================================================