PUT and PATCH are HTTP methods used in the context of RESTful APIs to perform different operations on a resource. Here are the five main differences between PUT and PATCH:
Idempotence:
PUT: The PUT method is idempotent, meaning that making the same request multiple times will have the same effect as a single request. If you send a PUT request with the same data multiple times, the resource state will be the same as if you had sent it once.
PATCH: The PATCH method is also designed to be idempotent, but its semantics are more focused on partial updates. Multiple identical PATCH requests should result in the same state as a single request, but the updates may be partial, affecting only specific parts of the resource.
Resource Update:
PUT: The PUT method is used to update or create a resource entirely. When you send a PUT request, you typically send the complete representation of the resource, and the server replaces the existing resource with the new representation.
PATCH: The PATCH method is used to apply partial modifications to a resource. Instead of sending the complete representation of the resource, you send only the changes you want to apply. The server then applies these changes to the existing resource.
Request Payload:
PUT: The request payload in a PUT request contains the full representation of the resource, even if you are only updating a small part of it. The entire updated resource needs to be sent in the request body.
PATCH: The request payload in a PATCH request contains only the changes to the resource. It is typically in a format such as JSON Patch or JSON Merge Patch, specifying the modifications to be applied.
Error Handling:
PUT: If a PUT request is made to a resource and the resource does not exist, the server may create the resource. However, if the resource already exists and the request payload is invalid, the server might reject the entire request.
PATCH: Since PATCH is designed for partial updates, it’s more tolerant of errors in the request payload. If some modifications in the PATCH request are invalid, the server can still apply the valid ones and respond accordingly.
Idempotent Handling of Arrays:
PUT: If a resource is an array, sending a PUT request with a new array completely replaces the existing array with the new one. The entire array is replaced, regardless of the differences between the new and existing arrays.
PATCH: When dealing with arrays, a PATCH request can be used to add, modify, or remove elements from the existing array without replacing the entire array. It allows for more granular updates to array elements.
In summary, PUT is generally used for full updates of a resource, while PATCH is used for partial updates, allowing clients to send only the modifications they want to apply to the server. Both methods are designed to be idempotent but have different use cases and semantics.