Hey there! Since you’ve already got your activity sessions list via the Sessions List API, let’s walk through how to pull the specific exportable data for a single session to integrate with services like Strava.

Step 1: Grab the Session ID from Your Existing List #

First, you’ll need the unique identifier for the session you want to export. Your sample session object only shows modifiedTimeMillis, but each entry in the session array will also have a sessionId field (a string like 1234567890123456789). That’s your key to target the exact activity you care about.

Step 2: Get Detailed Session Metadata with Sessions:get API #

Call the Sessions:get endpoint to retrieve full details about the session, including its time range and linked data sources. Here’s how to structure the request:

• Method: GET
• URL: https://www.googleapis.com/fitness/v1/users/me/sessions/{sessionId}
• Headers: Include your OAuth 2.0 access token: Authorization: Bearer YOUR_ACCESS_TOKEN

This response will give you critical fields you’ll need next:

• startTimeMillis and endTimeMillis (to define the bounds of your data request)
• dataSourceIds (an array of IDs pointing to where the raw activity data is stored)

Step 3: Fetch Raw Activity Data with DataSources.datasets.get #

Use each dataSourceId from the previous step to pull the actual raw datapoints. For every data source ID, call the Users.dataSources.datasets.get endpoint:

• Method: GET
• URL: https://www.googleapis.com/fitness/v1/users/me/dataSources/{dataSourceId}/datasets/{startTimeMillis}-{endTimeMillis}
• Headers: Same Authorization header as before

The response will include a point array with raw data entries. For example, a running session might return:

• Location datapoints (latitude/longitude pairs)
• Speed, pace, or heart rate values
• Cumulative distance metrics

Note on Pagination #

If your session has a lot of data (like a long run with frequent GPS points), the response might include a nextPageToken. Just append ?pageToken=TOKEN to the URL to fetch the remaining datapoints until there’s no more token.

Step 4: Convert Raw Data to Exportable Formats (e.g., .fit, GPX) #

Google Fit doesn’t return pre-formatted .fit or GPX files directly, but you can convert the raw datapoints using open-source libraries:

• For .fit files: Use a JavaScript library like fit-file-parser to map your datapoints into the .fit format schema (both parsing and building are supported).
• For GPX: Use tools like gpx-builder to convert location datapoints into valid GPX tracks—Strava supports GPX imports natively.

Example Snippet (GPX Conversion Concept) #

If you have location datapoints, here’s a quick pseudocode example to build a GPX track:

// Pseudocode for building GPX from location points
const gpxBuilder = new GPXBuilder();
const track = gpxBuilder.createTrack();
const segment = track.createSegment();

locationPoints.forEach(point => {
  segment.createPoint({
    lat: point.value[0],
    lon: point.value[1],
    time: new Date(parseInt(point.startTimeMillis))
  });
});

const gpxString = gpxBuilder.toString();

Key Permissions Reminder #

Make sure your OAuth 2.0 scope includes the necessary read access. For activity data, you’ll need https://www.googleapis.com/auth/fitness.activity.read (use write instead if you plan to modify data later).

内容的提问来源于stack exchange，提问作者Sankalp Sharma