HTTP Get with 204 No Content Is that normal

Question

Is it a normal occurrence for an HTTP GET Request to have a response with status code 204 - No Content  Like  is this semantically correct concerning what an HTTP GET is supposed to accomplish  I know that a 204 - No Content is okay for an HTTP POST-Request  For GET request  if no data is to be sent back  is the 204 status code appropriate  Should I use 404  or just stick to 200 for success but have an empty response   The use case for this question is a Java application that I am writing for Google App Engine  I am sending a request to a servlet  but the data to be sent back to the client will be transmitted through a Channel API socket instead of in the HTTP Response  Currently  my client sends a POST with no content in the request body and waits for a 204 response back from the servlet before polling the Channel API socket  Because no data I being sent in the body of the request  I am debating whether it makes more sense for me to send a GET instead of a POST

User · Answer

Http GET returning 204 is perfectly fine, and so is returning 404.

The important thing is that you define the design standards/guidelines for your API, so that all your endpoints use status codes consistently.

For example:

you may indicate that a GET endpoint that returns a collection of resources will return 204 if the collection is empty. In this case GET /complaints/year/2019/month/04 may return 204 if there are no complaints filed in April 2019. This is not an error on the client side, so we return a success status code (204). OTOH, GET /complaints/12345 may return 404 if complaint number 12345 doesn't exist.
if your API uses HATEOAS, 204 is probably a bad idea because the response should contain links to navigate to other states.

User · Answer

The POST GET with 204 seems fine in the first sight and will also work    Documentation says   2xx -- This class of status codes indicates the action requested by the client was received  understood  accepted  and processed successfully  whereas 4xx -- The 4xx class of status code is intended for situations in which the client seems to have erred   Since  the request was successfully received  understood and processed on server  The result was that the resource was not found  So  in this case this was not an error on the client side or the client has not erred   Hence this should be a series 2xx code and not 4xx  Sending 204  No Content  in this case will be better than a 404 or 410 response

User · Answer

Your current combination of a POST with an HTTP 204 response is fine     Using a POST as a universal replacement for a GET is not supported by the RFC  as each has its own specific purpose and semantics   The purpose of a GET is to retrieve a resource   Therefore  while allowed  an HTTP 204 wouldn t be the best choice since content IS expected in the response   An HTTP 404 Not Found or an HTTP 410 Gone would be better choices if the server was unable to provide the requested resource   The RFC also specifically calls out an HTTP 204 as an appropriate response for PUT  POST and DELETE  but omits it for GET   See the RFC for the semantics of GET   There are other response codes that could also be returned  indicating no content  that would be more appropriate than an HTTP 204   For example  for a conditional GET you could receive an HTTP 304 Not Modified response which would contain no body content

User · Answer

204 No Content      The server has fulfilled the request but does not need to return an   entity-body  and might want to return updated metainformation  The   response MAY include new or updated metainformation in the form of   entity-headers  which if present SHOULD be associated with the   requested variant    According to the RFC part for the status code 204  it seems to me a valid choice for a GET request   A 404 Not Found  200 OK with empty body and 204 No Content have completely different meaning  sometimes we can t use proper status code but bend the rules and they will come back to bite you one day or later  So  if you can use proper status code  use it   I think the choice of GET or POST is very personal as both of them will do the work but I would recommend you to keep a POST instead of a GET  for two reasons    You want the other part  the servlet if I understand correctly  to perform an action not retrieve some data from it  By default GET requests are cacheable if there are no parameters present in the URL  a POST is not

User · Answer

I use GET 204 with a RESTful collection that is a positional array of known fixed length but with holes     GET  items     200    a    b   null   GET  items 0     200   a   GET  items 1     200   b   GET  items 2     204   GET  items 3     404  Not Found

[google-app-engine] HTTP Get with 204 No Content: Is that normal

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