# Date Format Handling for ClickHouse Events API

## Problem Description

The event tracking API was experiencing issues with date format compatibility when inserting records into the ClickHouse database. ClickHouse has specific requirements for datetime formats, particularly for its `DateTime64` type fields, which weren't being properly addressed in the original implementation.

## Root Cause

- JavaScript's default date serialization (`toISOString()`) produces formats like `2023-08-24T12:34:56.789Z`, which include `T` as a separator and `Z` as the UTC timezone indicator
- ClickHouse prefers datetime values in the format `YYYY-MM-DD HH:MM:SS.SSS` for seamless parsing
- The mismatch between these formats was causing insertion errors in the database

## Solution Implemented

We created a `formatDateTime` utility function that properly formats JavaScript Date objects for ClickHouse compatibility:

```typescript
const formatDateTime = (date: Date) => {
  return date.toISOString().replace('T', ' ').replace('Z', '');
};
```

This function:
1. Takes a JavaScript Date object as input
2. Converts it to ISO format string
3. Replaces the 'T' separator with a space
4. Removes the trailing 'Z' UTC indicator

The solution was applied to all date fields in the event payload:
- `event_time`
- `link_created_at`
- `link_expires_at`

## Additional Improvements

- We standardized date handling by using a consistent `currentTime` variable
- Added type checking for JSON fields to ensure proper serialization
- Improved error handling for date parsing failures

## Best Practices for ClickHouse Date Handling

1. Always format dates as `YYYY-MM-DD HH:MM:SS.SSS` when inserting into ClickHouse
2. Use consistent date handling utilities across your application
3. Consider timezone handling explicitly when needed
4. For query parameters, use ClickHouse's `parseDateTimeBestEffort` function when possible
5. Test with various date formats and edge cases to ensure robustness