Using sensors in projects

Prerequisites

Before following this guide, you will need to create a project with the create-dagster CLI.

Assets and jobs frequently use sensors that are instantiated elsewhere in the project.

For example, if you have created a new Dagster project with dg called my_project, you can define the sensors at src/my_project/defs/sensors.py:

Sensor binding can happen at any level of the defs hierarchy. If you moved asset_one in this example to a subdirectory, you could leave the existing sensors.py file at src/defs/sensors.py:

src
└── my_project
    └── defs
        ├── assets
        │   └── asset_one.py # contains def asset_one():
        └── sensors.py # contains dg.sensor

Scaffolding sensors

To create a sensor dictionary like the above, you can run the following:

dg scaffold defs dagster.sensor sensors.py

which will create

src/<project_name>/defs/sensors.py

import dagster as dg


@dg.sensor(target=None)
def sensor(context: dg.SensorEvaluationContext) -> dg.SensorResult:
    return dg.SensorResult()

and you can fill out the sensor dictionary as needed.