REST's fifth HTTP method: PATCH?

The HTTP method PUT means resource creation or replacement at some given URL.

Think files, for example. If you upload a file to S3 at some URL, you want either to create the file at that URL or replace an existing file if there's one. That is PUT.

Now let's say a web application has an Invoice model with a paid flag that indicates whether the invoice has been paid. How do you set that flag in a RESTful way? Submitting paid=1 via PUT to /invoices/:id does not conform to the semantics, because such request would not be sending a complete representation of the invoice for replacement.

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In practice, as you see, PATCH suits everyday web programming way better than PUT for updating resources. In Ruby on Rails it corresponds naturally to the way we use update_attributes for updating records.

Thus, PATCH is going to be the primary method for updates in Rails 4.0.

via weblog.rubyonrails.org