SNOW-889293: Support json_serializer and json_deserializer engine/dialect paremeters

[edgarrmondragon]

What is the current behavior?

These parameters are not supported, causing engine creation which should work for a generic SQLAlchemy database, to fail:

import decimal
import json

import simplejson
import sqlalchemy

sqlalchemy.create_engine(
    "<a SF sqlalchemy URL>",
    echo=False,
    json_serializer=lambda obj: simplejson.dumps(obj, use_decimal=True),
    json_deserializer=lambda json_str: json.loads(json_str, parse_float=decimal.Decimal),
)

  File "/venv/lib/python3.9/site-packages/sqlalchemy/engine/create.py", line 632, in create_engine
    raise TypeError(          
TypeError: Invalid argument(s) 'json_serializer','json_deserializer' sent to create_engine(), using configuration SnowflakeDialect/QueuePool/Engine.  Please check that the keyword arguments are appropriate for this combination of components.

What is the desired behavior?

That these parameters are supported, given they are supported in all built-in SQLAlchemy dialects.

How would this improve snowflake-connector-python?

Not in any way, AFAICT.

References, Other Background

This should be as simple as overriding the constructor of SnowflakeDialect:

class SnowflakeDialect(default.DefaultDialect):
  def __init__(self, json_deserializer=None, json_serializer=None, **kwargs):
    default.DefaultDialect.__init__(self, **kwargs)
    self._json_deserializer = json_deserializer
    self._json_serializer = json_serializer

I can start working on a PR if the maintainers are interested.

See

• https://github.com/sqlalchemy/sqlalchemy/blob/f6c3b7c1bb1c2a3b4323a1e68aed77ee599a72b2/lib/sqlalchemy/dialects/sqlite/base.py#L1968-L1984
• https://github.com/sqlalchemy/sqlalchemy/blob/f6c3b7c1bb1c2a3b4323a1e68aed77ee599a72b2/lib/sqlalchemy/dialects/postgresql/base.py#L3032-L3043
• https://docs.sqlalchemy.org/en/14/core/engines.html#sqlalchemy.create_engine.params.json_deserializer
• https://docs.sqlalchemy.org/en/14/core/engines.html#sqlalchemy.create_engine.params.json_serializer

[sfc-gh-sfan]

Seems like a legit feature, what do you think @sfc-gh-aling ?

[movchan74]

Do you happen to have any update on this issue or a workaround? I'm running into the following error: AttributeError: 'SnowflakeDialect' object has no attribute '_json_deserializer'