Declarative Automation: Operands

Declarative Automation: Operands

Operands are base conditions that evaluate to true or false for a given asset or asset partition. They represent fundamental states and events.

Complete List of Operands

Status vs Event Operands

Status operands are persistent and remain true for multiple evaluations:

• missing() - Stays true until the asset is materialized
• in_progress() - True while a run is executing
• execution_failed() - True until the asset succeeds or is re-requested
• in_latest_time_window() - True for the latest time partition(s)
• will_be_requested() - True during the tick when a request will be made

Event operands are transient and true for only one evaluation:

• newly_updated() - True only on the tick when the update occurs
• newly_requested() - True only on the tick when the request is made
• code_version_changed() - True only on the first tick after the change
• cron_tick_passed() - True only on the first tick after the cron tick
• initial_evaluation() - True only on the very first evaluation

Detailed Descriptions

missing(): True if the asset partition has never been materialized or observed.

in_progress(): True if the asset partition is part of an in-progress run or backfill. Combines run_in_progress() and backfill_in_progress().

execution_failed(): True if the latest execution of the asset partition failed.

newly_updated(): True if the asset partition was materialized or observed since the previous evaluation. For observations, only true if the data version changed.

newly_requested(): True if the asset partition was requested on the previous evaluation tick.

code_version_changed(): True if the asset's code version has changed since the previous evaluation.

cron_tick_passed(cron_schedule, cron_timezone): True on the first evaluation after a tick of the specified cron schedule occurs.

Parameters:

• cron_schedule (str): Cron expression
• cron_timezone (str): Timezone string (default: "UTC")

in_latest_time_window(lookback_delta): True for time partitions within the latest time window. For unpartitioned or non-time-partitioned assets, always true.

Parameter:

• lookback_delta (Optional[timedelta]): If provided, returns partitions within this delta of the latest window end. For daily partitions with lookback_delta=timedelta(hours=48), returns the latest 2 partitions.

will_be_requested(): True if the asset partition will be requested in the current tick. Used internally for run grouping (see advanced.md).

initial_evaluation(): True only on the first evaluation after the condition is applied or modified.

Composite Conditions

Built from base operands for convenience:

Usage

Operands are composed using operators (see operators.md) to build complex conditions:

import dagster as dg

# Using operands directly
condition = dg.AutomationCondition.missing() & ~dg.AutomationCondition.in_progress()

# Using composite conditions
condition = dg.AutomationCondition.any_deps_updated()