PUT vs PATCH: When to Use Each in REST APIs

PUT: Full Resource Update

PUT is used to completely replace an existing resource or create a new one if it doesn't exist.

Characteristics of PUT:

• Idempotent: Multiple identical requests will have the same effect as a single request.
• Replaces the Entire Resource: The entire resource must be sent in the request.
• Requires Full Payload: Even if only one field is changing, the entire resource must be included in the request.

Example: If updating a user profile with PUT, you need to send the complete profile data to replace the existing profile.

PATCH: Partial Resource Update

PATCH is used to apply partial modifications to a resource.

Characteristics of PATCH:

• Not Necessarily Idempotent: PATCH requests may not have the same effect when repeated.
• Updates Only Specified Fields: Only the fields that are being changed need to be included.
• More Efficient: Ideal for making small updates to large resources without sending the entire payload.

Example: If updating only the email address of a user profile with PATCH, you only send the new email address.

Key Differences:

1. Completeness: PUT replaces the entire resource, while PATCH updates only part of it.
2. Idempotency: PUT is idempotent, whereas PATCH may not be.
3. Efficiency: PATCH is more efficient for partial updates, especially for large resources.
4. Creation: PUT can create a new resource if it doesn’t exist, but PATCH typically cannot.
5. Payload: PUT requires the full resource representation, while PATCH only requires the changes.

When to Use Each:

• Use PUT when:

  • Updating an entire resource.
  • Creating a resource when the client knows the URL.
  • Idempotency is a key requirement.

• Use PATCH when:

  • Partially updating a resource.
  • Dealing with large resources where sending the entire payload would be inefficient.
  • The client only knows a portion of the resource’s state.