Export and persist data

Use the public exporters for event output. EventExporterGPX writes activities with positional data as GPX; activities without positional data do not contribute tracks to the result.

import { EventExporterGPX, SportsLib } from '@sports-alliance/sports-lib';

const event = await SportsLib.importFromFit(fitArrayBuffer);
const exporter = new EventExporterGPX();
const gpxText = await exporter.getAsString(event);

const file = new Blob([gpxText], { type: exporter.fileType });
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GPX represents both cadence and stroke rate through its cadence extension. EventExporterGPX writes the canonical Stroke Rate stream there for supported stroke-rate activities so the values survive a GPX round trip.

Native JSON round trips

Native JSON is the persistence format for the Sports Lib model. Call toJSON() to obtain the typed contract and restore it with the corresponding SportsLib method. Restoration preserves explicit stats except terrain summaries excluded for the Diving activity group, canonicalizes compatible legacy keys, may add missing speed-derived pace summaries on events, activities, and laps, and applies activity-aware cadence-to-stroke-rate normalization without requiring the original source file.

Starting with 20.0.2, restoring older Diving-group JSON also removes terrain ascent/descent, altitude min/max/avg, and grade min/max/avg summaries from events, activities, and laps. The restored model needs no source-file reparse; re-serializing it intentionally writes the corrected summary set while retaining any raw source streams.

import { EventExporterJSON, SportsLib } from '@sports-alliance/sports-lib';

const eventJson = event.toJSON();
const restoredEvent = SportsLib.importFromJSON(eventJson);

const jsonText = await EventExporterJSON.getAsString(event);
const restoredFromText = SportsLib.importFromJSON(JSON.parse(jsonText));

const routeJson = routeFile.toJSON();
const restoredRouteFile = SportsLib.importRoutesFromJSON(routeJson);
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The EventJSONInterface and RouteFileJSONInterface API pages describe the JSON shapes. Use native route JSON when route metadata must be retained beyond FIT Course capabilities.