Event Validation

Event validation is checking an incoming event against a defined expectation before accepting it: the right name, the required properties, and the correct data type for each value.

Validation is the line of defense between instrumentation and clean data; without it every code error goes straight into the report, and because past data cannot be repaired, the cost is lasting. What it does is match an event against a source of truth, usually the tracking plan or an event schema: a name not on the allowed list, a required property that is missing, or a value that should be a number but arrived as a string are all flagged or rejected. A key decision is whether an invalid event is rejected or accepted with a warning; strict rejection keeps data clean but may drop a real event, while accepting with a warning preserves data but defers the tidiness. The choice depends on whether losing data or polluting it is the costlier failure.