REST API using POST instead of GET

Question

Let s assume a service offers some funcionality that I can use like this   GET  service function param1 value1 amp param2 value2   Is it right to say that I can use it with a POST query   POST  service function   param1   value1  param2   value2     Are these two queries the same  Can I use the second variant in any case or the documentation should explicitly say that I can use both GET and POST queries

User · Answer

Think about it  When your client makes a GET request to an URI X  what it s saying to the server is   I want a representation of the resource located at X  and this operation shouldn t change anything on the server   A PUT request is saying   I want you to replace whatever is the resource located at X with the new entity I m giving you on the body of this request   A DELETE request is saying   I want you to delete whatever is the resource located at X   A PATCH  is saying  I m giving you this diff  and you should try to apply it to the resource at X and tell me if it succeeds   But a POST is saying   I m sending you this data subordinated to the resource at X  and we have a previous agreement on what you should do with it     If you don t have it documented somewhere that the resource expects a POST and does something with it  it doesn t make sense to send a POST to it expecting it to act like a GET   REST relies on the standardized behavior of the underlying protocol  and POST is precisely the method used for an action that isn t standardized  The result of a GET  PUT and DELETE requests are clearly defined in the standard  but POST isn t  The result of a POST is subordinated to the server  so if it s not documented that you can use POST to do something   you have to assume that you can t

User · Answer

It is nice that REST brings meaning to HTTP verbs  as they defined  but I prefer to agree with Scott Peal    Here is also item from WIKI s extended explanation on POST request      There are times when HTTP GET is less suitable even for data retrieval  An example of this is when a great deal of data would need to be specified in the URL  Browsers and web servers can have limits on the length of the URL that they will handle without truncation or error  Percent-encoding of reserved characters in URLs and query strings can significantly increase their length  and while Apache HTTP Server can handle up to 4 000 characters in a URL  5  Microsoft Internet Explorer is limited to 2 048 characters in any URL  6  Equally  HTTP GET should not be used where sensitive information  such as user names and passwords  have to be submitted along with other data for the request to complete  Even if HTTPS is used  preventing the data from being intercepted in transit  the browser history and the web server s logs will likely contain the full URL in plaintext  which may be exposed if either system is hacked  In these cases  HTTP POST should be used  7    I could only suggest to REST team to consider more secure use of HTTP protocol to avoid making consumers struggle with non-secure  good practice

User · Answer

I use POST body for anything non-trivial and line-of-business apps for these reasons   Security - If we use GET with query strings and https  the query strings can be saved in server logs and forwarded as referral links  Both of these are now visible by server network admins and the next domain the user went to after leaving your app  So if we send a query containing confidential PII data such as a customer s name this may not be desired  URL maximum length - Not a big issue  but some browsers have a limit on the length  So if we have several items in our URL like query  paging  fields to return  etc     POST is not cached by default  Some say caching is desired  however  how often is that exact same set of search criteria for that exact object for that exact customer going to occur before the cache times out anyway   BTW  I also put the fields to return in my POST body as I may not wish to expose my field names  Security is like an onion  it has many layers and makes us cry

User · Answer

POST is valid to use instead of GET if you have specific reasons for doing so and process it properly  I understand it s not specifically RESTy  but if you have a bunch of spaces and ampersands and slashes and so on in your data  eg a product model like Amazon  then trying to encode and decode this can be more trouble than it s worth instead of just pre-jsonifying it  Make sure though that you return the proper response codes and heavily comment what you re doing because it s not a typical use case of POST

User · Answer

In REST  each HTTP verbs has its place and meaning   For example    GET is to get the  resource s   that is pointed to in the URL  POST is to instructure the backend to  create  a resource of the  type  pointed to in the URL  You can supplement the POST operation with parameters or additional data in the body of the POST call    In you case  since you are interested in  getting  the info using query  thus it should be a GET operation instead of a POST operation   This wiki may help to further clarify things   Hope this help

User · Answer

Just to review  REST has certain properties that a developer should follow in order to make it RESTful   What is REST   According to wikipedia      The REST architectural style describes the following six constraints   applied to the architecture  while leaving the implementation of the   individual components free to design          Client   server  Servers are not concerned with the user interface or user state  so that servers can be simpler and more scalable    Stateless  The client   server communication is further constrained by no client context being stored on the server between requests    Cacheable  Responses must  implicitly or explicitly  define themselves as cacheable  or not  to prevent clients reusing stale or inappropriate data in response to further requests    Layered system  A client cannot ordinarily tell whether it is connected directly to the end server  or to an intermediary along the way  Intermediary servers may improve system scalability by enabling load-balancing and by providing shared caches    Code on demand  optional   Servers can temporarily extend or customize the functionality of a client by the transfer of executable code    Uniform interface  The uniform interface between clients and servers  discussed below  simplifies and decouples the architecture  which enables each part to evolve independently   i e  HTTP GET  POST  PUT  PATCH  DELETE       What the verbs should do  SO user Daniel Vasallo did a good job of laying out the responsibilities of these methods in the question Understanding REST  Verbs  error codes  and authentication      When dealing with a Collection URI like  http   example com resources       GET  List the members of the collection  complete with their member   URIs for further navigation  For example  list all the cars for sale       PUT  Meaning defined as  replace the entire collection with another   collection        POST  Create a new entry in the collection where the ID is assigned   automatically by the collection  The ID created is usually included as   part of the data returned by this operation       DELETE  Meaning defined as  delete the entire collection     So  to answer your question      Is it right to say that I can use it with a POST query           Are these two queries the same  Can I use the second variant in any case or the documentation should explicitly say that I can use both GET and POST queries    If you were writing a plain old RPC API call  they could technically interchangeable as long as the processing server side were no different between both calls  However  in order for the call to be RESTful  calling the endpoint via the GET method should have a distinct functionality  which is to get resource s   from the POST method  which is to create new resources    Side note  there is some debate out there about whether or not POST should also be allowed to be used to update resources    though i m not commenting on that  I m just telling you some people have an issue with that point

User · Answer

You can t use the API using POST or GET if they are not build to call using these methods separetly  Like if your API say   service function param1 value1 amp param2 value2   is accessed by using GET method  Then you can not call it using POST method if it is not specified as POST method by its creator  If you do that you may got 405 Method not allowed status   Generally in POST method you need to send the content in body with specified format which is described in content-type header for ex  application json for json data   And after that the request body gets deserialized at server end  So you need to pass the serialized data from the client and it is decided by the service developer    But in general terms GET is used when server returns some data to the client and have not any impact on server whereas POST is used to create some resource on server  So generally it should not be same

User · Answer

If I understand the question correctly  he needs to perform a REST GET action  but wonders if it s OK to send in data via HTTP POST method   As Scott had nicely laid out in his answer earlier  there are many good reasons to POST input data  IMHO it should be done this way  if quality of solution is the top priority   A while back we created an REST API to authenticate users  taking username password and returning an access token  The API is encrypted under TLS  but exposed to public internet  After evaluating different options  we chose HTTP POST for the REST method of  GET access token   because that s the only way to meet security standards

[api] REST API using POST instead of GET

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