What criteria should be used when choosing HTTP methods POST, PUT, and PATCH for resource update operations?

The choice of HTTP method for updating resources depends on the nature of the operation:

• POST: Usually used for creating new resources or performing non-idempotent actions. Suitable for updates if they are partial and non-idempotent, but more often not used.

• PUT: An idempotent method that replaces the entire resource. If the client sends a complete object and the server replaces the existing resource with this object, PUT is used.

• PATCH: Designed for partial updates of a resource. The client sends only the changed fields, and the server applies these changes without replacing the entire object.

Example:

• Update the entire user profile — PUT with the full object.
• Change only the email — PATCH with the email field.

Thus, choose PUT for full replacement and PATCH for partial updates.