Comment by unregistereddev | Hacker News Reader

Comment by unregistereddev | Hacker News Reader

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unregistereddev

I agree - though I also agree with the author that this is an area where REST specifications are a little clunky.

Yes, `api/v1/employees/100` should return a 404, because that path represents the location of a specific entity and that entity does not exist.

Just as the author thinks it's clunky to return HTTP error codes representing application errors, I think it's clunky to apply application logic to HTTP method semantics. GET, POST, and DELETE were designed as instructions telling a web server how to handle static-ish content, and it shows in their design. Why would a GET have a body? It's a request for the server to return a specific file. This leads to breaking REST standards - for example, search endpoints that logically are GET calls (they return entities), but are implemented as POST methods because the search criteria is complex enough that you wanted a request body. Or bulk delete calls that are similarly implemented as POST methods.

REST works best in a "rules are meant to be broken" manner in my opinion. It's not a bad system (which is why it is so common), but mixing application logic with HTTP transport logic does lead to oddities.

Some applications opted for using GET with request bodies as well, for better or worse. Elasticsearch comes to mind.

There have been some attempts to extend the list of http verbs to include something that fits those use cases more naturally - SEARCH and QUERY. QUERY got more traction, if I remember correctly, but I haven't heard much about it in a while.

https://www.w3.org/2012/ldp/wiki/Proposal_for_HTTP_QUERY_Ver...

SEARCH is used by the WebDAV standard, not that I like WebDAV search syntax https://gist.github.com/CarlSchwan/66fde29d52022c0ef76aec362...

> SEARCH is used by the WebDAV standard

That’s probably part of the reason the more general one proposed for HTTP is “QUERY” and not “SEARCH”. Also, WebDAV, in following its apparent design philosophy of “more is more”, has multiple different GET-with-(required or optional)-body methods with different purposes: PROPFIND and REPORT as well as SEARCH.

You might like QUERY: https://www.ietf.org/archive/id/draft-ietf-httpbis-safe-meth...

>Yes, `api/v1/employees/100` should return a 404, because that path represents the location of a specific entity and that entity does not exist.

A GET request to that path should return the current state of the resource at the path. As you note, the current state of that entity is that it does not exist.

Let's look at the spec:

>200 OK - The request has succeeded. The information returned with the response is dependent on the method used in the request, for example:

> GET an entity corresponding to the requested resource is sent in the response;

Did the request succeed?

Yes, we found the current state of the entity so we return 200

What do we return?

"An entity corresponding to the requested resource". In this case however we want to represent an entity that doesn't exist.

> A GET request to that path should return the current state of the resource at the path

There is no resource at the path.

> As you note, the current state of that entity is that it does not exist.

A thing which does not exist does not have state. Existence (and even moreso non-existence) isn’t a state, existence is logically presupposed in any description of state.

>existence is logically presupposed in any description of state

Then please explain how you can write and I can understand the phrase "A thing which does not exist".

Its convenient linguistic shorthand for a common case which would be more properly be described as “a concept of a thing which does not correspond to any actual thing”. While the equivalent linguistic shorthand has been present in most languages for quite a long time, the recognition that the confusion it can sometimes produce between concepts and concrete things is a category error is, while not nearly as old, also fairly old; it is central to Kant’s argument against the ontological argument for God’s existence, for instance.

And why shouldn't we go with the convenient linguistic shorthand instead of the esoteric ontological argument?

> And why shouldn't we go with the convenient linguistic shorthand

Who said you shouldn't? The shorthand is convenient. But it doesn't mean what other statements with the same shape mean. A thing which isn't doesn't have a state or representation.

`100` could be the employee id more than a name of the employee. So a query for id 100 returns the information associated with that id, nominally that it is currently free and not associated with any employee.

Many online REST discussions focus too much on shallow linguistic analogies with verbs/nouns.

> So a query for id 100 returns the information associated with that id, nominally that it is currently free and not associated with any employee

If you were doing a static website serving from a file system and said the same thing about a filename as a path component, you'd be seen as mad. But there is no difference when there is an id for a potential employee than a name for a potential file: if no employee/file exists when the server looks for the id/name, the correct result is 404 Not Found.

The id isn't the resource, it's part of the path to the resource (and if it is the resource in that URL, you need a different scheme for when you need to find the employee pointed to by the id and not info about the id.)

That is defined by the previous segment of the path.

The content of the file `/api/v1/employees/100` need to be defined off-band somehow since you cant actually put an employee on disk.

moreover part of REST is that you are not responding with static files by path, but with representations of entities; the question then is whether the entity is the employee or the id.

I agree that `/api/v1/employees/100` is not the best name for the id entity, something like `/api/v1/employee-id-status/100` might be more descriptive.

If you have POST for search and bulk delete, you are "doing REST wrong" and calling RPC by another name.

Not true.

The "doing REST wrong" was in quotes to express that the practice might be widely accepted but it is not exactly kosher.

In "true" REST, if you have a "search" endpoint, POSTing to it should create to a resource, which could be a reference to the list of results. The created resource should have its own endpoint (something like `/search/results/:query_id`), and the client could then cache it.

If you don't want to do that, but still want to say you are really following REST, you could have an endpoint to represent your resources (`/products`) and use GET with filter parameters in the query string (`/products?search=my+search+term`)

this

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