Dagster Metadata and Result Payloads¶

Dagster users care about metadata-rich execution. Truthound supports that by converting shared quality results into Dagster-native metadata rather than inventing a separate result model.

Who This Is For¶

asset owners surfacing quality state in Dagster UI
platform teams building dashboards from asset metadata
engineers debugging how a Truthound result appears inside Dagster

When To Use It¶

Use this page when:

a check passes but operators still need detailed metadata
an asset check should expose failure counts and quality percentages
you need to translate a shared result into Dagster-native display fields

Prerequisites¶

a Dagster project using DataQualityResource, ops, or asset helpers
familiarity with to_dagster_metadata
understanding of the shared result contract

Minimal Quickstart¶

Use the utility directly when custom wrapping is needed:

from truthound_dagster import to_dagster_metadata

metadata = to_dagster_metadata(check_result)

For resource-driven checks, keep the result shared and let Dagster-specific metadata wrap it:

def validated_users(data_quality):
    result = data_quality.check(
        load_users(),
        rules=[{"column": "id", "check": "not_null"}],
    )
    return result

Production Pattern¶

Think in layers:

Layer	Purpose
shared Truthound result	canonical status, counts, and detailed failures
Dagster metadata	UI-friendly display, asset context, and operator navigation

Recommended practices:

keep the shared result available for programmatic use
use Dagster metadata for display and run inspection
avoid custom ad hoc metadata keys when shared ones already exist

Failure Modes and Troubleshooting¶

Symptom	Likely Cause	What To Do
metadata is present but hard to automate	only human-readable strings are emitted	preserve structured shared results alongside metadata
alerting loses quality detail	only Dagster event success/failure is read	include summary counts from the serialized result
two assets show different quality formatting	custom metadata wrappers diverged	standardize on `to_dagster_metadata`