When using

partition_mappings

for an asset, is there any way to get the exact set of the mapped partitions of the upstream asset? I understand how to access the partitions range with

range_start, range_end = context.asset_partition_key_range

, but I would like to have the exact set, because it may differ for different partitioning schemas (daily, monthly, etc). Seems like

dagster.core.definitions.time_window_partitions.TimeWindowPartitionsDefinition.get_partitions

would help, but I don't know how to access it from the IO Manager context. Any help?

Hey Daniel - we don't currently provide a function that gives the exact set within a range, however, you can get the partitions definition from

context.asset_output_info.partitions_def

on an

OutputContext

. I'd recommend using

get_partition_keys

instead of

get_partitions

, because the latter returns

Partition

objects instead of strings, which might not be supported in the future

Thanks! In Dagster 0.15.4 I found this attribute (for InputContext):

context.upstream_output.asset_info.partitions_def

I assume this is the one I need? There is no

asset_output_info

attribute.