How do you use validation groups with class-validator to apply different rules for create vs update operations in NestJS?
class-validator supports groups — decorators declare which groups they belong to, and ValidationPipe is configured with a specific group to run. Extend ValidationPipe with different group settings for create (all fields required) and update (all fields optional) handlers.
Validation groups for create and update DTOs
Validation group patterns:
Decorators without a groups option apply to ALL groups — always specify groups explicitly.
Use skipMissingProperties: true on update groups so absent fields are not treated as errors.
Groups are passed as a string array — multiple groups can be active simultaneously.
A decorator with groups: ['create'] is completely ignored during update validation.
For simple create/update patterns, separate CreateDto and UpdateDto classes (with PartialType) is often cleaner.