Measurement Metadata

You can provide custom metadata when creating a new instrument or when invoking the done() or fail() methods of an instrument.

Providing metadata is useful for:

• Filtering measurements when creating indicators in Polaris.
• Providing additional context when debugging issues.

Let's take a look at an example of each.

Add Metadata

Let's add custom metadata to a measurement.

export function App() {
  const instrument = useInstrument('event-name');

  useEffect(() => {
    instrument.start({
      tier: user.tier
    });
  }, [instrument]);
}

Let's review the code above.

• We create a new instrument using the useInstrument() hook.
• We start the measurement using the start() method of the Instrument.
• When starting the measurement we optionally provide the metadata object. In this case we are providing the tier of the user.

Add Metadata when Completing a Measurement

You can also add metadata when invoking the done() or fail() methods on the Instrument.

export function App() {
  useEffect(() => {
    instrument.start();
    authenticate()
      .then(() => instrument.done({
        attribute3: 'value3',
        attribute4: 'value4',
      }))
      .catch((error) => instrument.error({ error, attribute5: 'value5', attribute6: 'value6' }));
  }, [authenticate, instrument]);
}

Let's review the code above.

• We create a new instrument using the useInstrument() hook.
• We start the measurement using the start() method of the Instrument.
• We invoke the done() method of the Instrument when the authentication is successful.
• We invoke the fail() method of the Instrument when the authentication fails.