How to Validate Go Structs Using Tags Instead of Manual If Chains

A practical guide published on DEV Community demonstrates how to validate and normalize a Go signup form using struct tags with the open-source Checker library. The approach replaces hand-written conditional logic by defining validation rules — such as trimming whitespace, enforcing minimum length, and matching cross-field values — directly as tag annotations on struct fields. The library's CheckStruct function both normalizes input in-place and validates it in a single pass, eliminating the need for a separate sanitization step. When validation fails, errors are returned as a field-keyed map that serializes directly to a JSON response containing machine-readable codes and human-readable messages. The guide also covers slice field validation, where a prefix notation allows per-element rules alongside collection-level constraints like maximum length.