Via https://github.com/mongodb-labs/mongo-arrow/issues/253

```

Hi, I hope you're all having a wonderful day.

I have a redshift table that includes 4 columns, two of the columns are string version of ObjectId.

I load the data in polars and then apply the following code.

` assignment_fwks = assignment_fwks.with_columns(
            pl.col("profile_id").map_elements(ObjectId, return_dtype=pl.Object).alias("profile_id"),
            pl.col("framework_id").map_elements(ObjectId, return_dtype=pl.Object).alias("framework_id"))`
        
        
However, when I do 

`pymongoarrow.api.write(my_collection, assignment_fwks)`

I get the error, 

`Exception has occurred: PanicException
called Option::unwrap() on a None value
  File "/home/ubuntu/projects/profile_assigner/src/consumption_assignments/app.py", line 49, in upsert_profile_assignment
    result = write(coll, insertion_fwk_assignments)
  File "/home/ubuntu/projects/profile_assigner/src/consumption_assignments/app.py", line 105, in client_profile_assignments
    upsert_profile_assignment(
  File "/home/ubuntu/projects/profile_assigner/src/consumption_assignments/app.py", line 136, in main
    client_error = client_profile_assignments(region, cli_region_df, credentials)
  File "/home/ubuntu/projects/profile_assigner/src/consumption_assignments/app.py", line 149, in <module>
    main()
pyo3_runtime.PanicException: called Option::unwrap()`

If i don't convert these columns to ObjectId and keep them as strings, then it works fine and inserts the data correctly into the mongo collection.

So is there a way I can convert these string columns to ObjectIds and do the insertion to mongo collection, without explicitly having to convert to another data structure like pandas dataframe or List?

```

As long as i can use the arrow format it would be great. As it is very memory and cost efficient.