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Title
# ask-ai
z

Zaighum Rajput

03/12/2024, 2:48 AM
How can I get the partitionsdef for a sensor?
s

Scout

03/12/2024, 2:48 AM
To get the
PartitionsDefinition
for a sensor, you typically define the partitions within the asset or job that the sensor is monitoring. The sensor itself does not have a
PartitionsDefinition
, but it can trigger runs based on partition information from the assets or jobs it targets. If you have an asset or job with a defined
PartitionsDefinition
, you can use that information within a sensor to create `RunRequest`s for specific partitions. For example, if you have an asset with a
DailyPartitionsDefinition
, you can write a sensor that triggers a run for a specific partition key. Here's a simplified example based on the documentation:
Copy code
python from dagster import sensor, RunRequest, DailyPartitionsDefinition, asset  partitions_def = DailyPartitionsDefinition(start_date="2021-01-01")  @asset(partitions_def=partitions_def) def my_asset():     # Asset logic here     ...  @sensor(job=my_asset) def my_sensor():     partition_key = "2021-01-02"  # Determine the partition key dynamically as needed     return RunRequest(         run_key=f"run_for_{partition_key}",         tags={"dagster/partition": partition_key}     )
In this example,
my_sensor
is a sensor that creates a
RunRequest
for a specific partition of the
my_asset
asset. The partition key is specified in the
tags
dictionary with the key
"dagster/partition"
. If you need to retrieve the partition keys from a
DynamicPartitionsDefinition
, you can use the
get_partition_keys
method, which requires access to the instance and the
DynamicPartitionsDefinition
. This method is not directly related to sensors but can be used within a sensor to determine which partitions to trigger. Remember that the sensor's logic should determine which partition keys to use when creating run requests, and it can use the partition definitions associated with the assets or jobs it targets to inform that logic.
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