Both PATCH and PUT are HTTP methods primarily used for modifying existing resources on the server. However, there are key differences in how they handle resource updates:
1. Update Scope
PUT： PUT is typically used for updating the entire resource. If you need to replace the complete content of a resource or fully overwrite an existing record, use PUT. When making a PUT request, you must provide the complete resource representation, including unchanged fields.
Example： Consider a user information API containing the user's name, email, and password. To update the user's email, a PUT request would typically require sending the full dataset (name, email, and password), even if only the email has changed.
PATCH： PATCH is used for partial updates, modifying only specific parts of the resource. With PATCH, you only need to send the changed fields.
Example： Using the same user information example, updating only the email with PATCH requires sending just the new email value. This approach is more efficient, especially when the resource contains a large amount of unchanged data.
2. Idempotency
PUT： PUT is idempotent, meaning repeated identical requests (with the same content and target resource) produce the same result as a single request.
PATCH： PATCH is often implemented as idempotent, but this depends on the implementation. Theoretically, PATCH requests can be non-idempotent if the operation depends on the resource's current state (e.g., incrementing a numeric value by a specific amount).
Summary
Selecting between PUT and PATCH depends on your specific use case. Use PUT when replacing the entire resource content, as it ensures consistency. Use PATCH for partial updates, as it is more efficient and aligns with RESTful principles. Proper method selection enhances performance and adheres to REST architectural standards.