Would love to have a simple function that would "smart-cast" dictionaries into metadata for assets. We have several flows where we produce a dictionary of metadata about an object, and then log it, like so:

@asset
def my_asset():
   # code to actually create the asset
   object_id = do_something()

   # code to do a /describe call from an api
   details = requests.get(f"some_url/{object_id")
   context.add_output_metadata(details)

   return object_id

However, we frequently hit errors in the ops this way, especially around array values:

dagster._core.errors.DagsterInvalidMetadata: Could not resolve the metadata value for "public_access_id" to a known type. Its type was <class 'NoneType'>. Consider wrapping the value with the appropriate MetadataValue type.

. Would be great to have a

sanitize_metadata

argument that by default drops unparseable values, or something.

Or even bricks dagit UI as JavaScript is less lenient than Python with regards to json Iike data

here's my simplistic workaround right now:

def sanitize_metadata_dict(metadata_dict: dict) -> dict:
    "Sanitizes a raw Python dict so that it can be cast to Dagster metadata"
    sanitized = dict()
    for k, v in metadata_dict.items():
        if isinstance(v, str):
            sanitized[k] = v
        elif isinstance(v, int) or isinstance(v, float):
            sanitized[k] = v
        elif isinstance(v, dict):
            sanitized[k] = sanitize_metadata_dict(v)
        else:
            logger.debug("Noncompliant metadata key found (%s). Removing.", type(v))
    return sanitized

Perhaps doesn't solve the general annoyance, but we've been considering adding a NoneableMetadataValue that could help solve the particular issue with None. Added an issue for this: https://github.com/dagster-io/dagster/issues/10080

awesome, yeah, that would help. The one I most frequently hit is with

list

, would be great to handle that too