Fix React serialization warning when passing ObjectIds to client components:
**Problem:**
- MongoDB ObjectIds have toJSON() methods which React rejects in client components
- Error: "Only plain objects can be passed to Client Components from Server Components. Objects with toJSON methods are not supported"
- Occurred when rendering main page with year parameter (?year=2023)
**Solution:**
- Add $addFields stage in fetchAllLocations aggregation pipeline
- Convert location _id and bill _id fields to strings using $toString
- Simplify $project stage to use single "bills": 1 instead of individual field projections
- Ensures only plain objects (strings) are passed to client components
**Technical Details:**
- Modified app/lib/actions/locationActions.ts:268-287
- Added $addFields stage before existing $project stage
- Converted ObjectIds to strings while preserving all other data structures
- Build passes without serialization warnings
ObjectId serialization now handled properly across all client component boundaries.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
Nikola Derežič
fdfa23e67d