HTTP Methods

When deciding on which HTTP method to use, always consider it from the client's perspective.

ex. if the UI of a webapp has an option to delete content, you may decide that your backend will only soft-delete that content (ie. it will keep the data in the database, but give it a flag such as isDeleted: true). This implementation detail is of no concern to the client, and therefore while we may be tempted to implement this functionality as a PATCH (since we are modifying data instead of actually deleting it), because the client has no knowledge of that, we should use the DELETE HTTP method.

GET

Use POST when you want to create resources without knowing the URI for the new resource

however, a POST does not necessarily have to result in a resource that can be identified by a URI.
POST requests are never cached
POST requests do not remain in the browser history
POST requests cannot be bookmarked
POST requests have no restrictions on data length
POST requests are not idempotent

200 (OK) - more than 1 resource created
201 (Created) - only 1 resource created
204 (No Content) - no new resource created (or if a resource was created, but the response doesn't include an entity that describes the result)
400 (Bad Request)

For PUT requests the client needs to know the exact URI of the resource.

ex. We cannot send a PUT request to /projects and expect a new resource to be created at /projects/123
this doesn't mean we can't create new resources with PUT; but it does mean the client needs to know how to generate the URI/ID of the new resource.
- In cases where this ID is knowable by the client, PUT should actually be preferred over POST, since PUT is idempotent.
Therefore, PUT can be thought of as "create or update" resource.

PUT should replace the existing resource with the new one. This means we cannot do partial updates.

if we want to mimic a partial update, then we'd have to send the whole resource (with the modified field).

201 (Created) - a new resource is created
200 (OK) - an existing resource is modified
204 (No Content) - an existing resource is modified, but the entity isn't included in the response