Meltano

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Hi everyone, I’m trying to store DynamoDB JSON objects as string on BigQuery, and using stream maps for that.
The stream maps work fine when the JSON object is present in the record, but the new records don’t have the field present immediately, which is breaking the stream map. Tried using `self` as the documentation seemed like it takes care of value present or not, but got error that `self` is not defined in the first place.
Can somebody please help me transform the field to string if it exists, and do nothing if it doesn’t?

<@U06CBGYV5NX> I'm not sure about the `self` issue but similar to this example <https://docs.meltano.com/guide/mappers#example> you should be able to use a default value with the python get() method like:
```transactionId: str(record.get('transactionId', ''))```

I'm using a standalone mapper for this example since my plugins were not SDK based but I do something similar for a case where my json record either has `ipv4prefix` or `ipv6prefix` and never both, so I parse out each and default to an empty string if it doenst exist <https://github.com/meltano/squared/blob/f0048719743862a4f4601b152e6606e3280e6f83/data/extract/mappers.meltano.yml#L13>