I’m currently developing a REST API and I’m a bit uncertain about the differences between using PUT and PATCH methods for updates.
As I understand it, PUT is meant to replace the entire resource, while PATCH allows for updating just specific attributes. However, I’m unclear on the actual instances where one would prefer to replace an entire resource instead of just modifying certain parts.
For instance, consider a user resource that looks like this:
{
"id": 42,
"name": "john_doe",
"email": "[email protected]",
"status": "active"
}
If I only want to change the email address, I could use PATCH like this:
{"email": "[email protected]"}
So, what would be a suitable scenario to use PUT? Would I need to send the entire user object even if just one field is being changed?
Additionally, I learned that PATCH isn’t considered idempotent, and I’m puzzled by this point. If I keep sending the same PATCH request to change the email address, shouldn’t the outcome always be the same?
Could someone clarify under what circumstances PUT is more appropriate than PATCH? I’m trying to set up my API endpoints effectively but I’m facing some challenges with this choice.
I use PUT for config objects and settings where I want the entire state explicitly defined. Like user preferences or app settings - PUT ensures any missing fields get set to defaults or removed completely. No stale data hanging around. The PATCH idempotency thing trips people up because of how it’s implemented. Sure, replacing an email field looks idempotent, but PATCH can do stuff like ‘increment counter by 5’ or ‘add item to array.’ Run those multiple times and you’ll get different results each time. That’s why PATCH isn’t guaranteed idempotent by spec. I use PUT when the client has the complete resource state, PATCH for small updates where bandwidth matters. Just stay consistent across your API.
honestly, just think about what your frontend sends. if it’s a typical edit profile page where users fill out all the fields anyway, go with put - way simpler validation on the backend. patch gets messy with nested objects or arrays. i’ve seen way too many bugs from patch operations that don’t handle edge cases right.
The PATCH idempotency issue can be confusing because it relies on your specific implementation. For instance, operations like {“email”: “[email protected]”} can be treated as idempotent in practice. However, the HTTP specification does not guarantee this, as PATCH could potentially modify resources in ways that are not idempotent, such as appending to arrays. I generally opt for PUT when the client has the full state of the resource and needs to replace it entirely, like when editing a form with all fields or performing bulk updates. For your user example, using PUT makes sense if your frontend collects all user data, even if only the email changes. In contrast, PATCH would be more appropriate for targeted updates, as it only requires the changed attributes.