Is there any standard for JSON API response format

Question

Do standards or best practices exist for structuring JSON responses from an API   Obviously  every application s data is different  so that much I m not concerned with  but rather the  response boilerplate   if you will   An example of what I mean   Successful request        success   true     payload            Application-specific data would go here             Failed request        success   false     payload            Application-specific data would go here             error          code   123       message    An error occurred

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Best Response for web apis that can easily understand by mobile developers.

This is for "Success" Response

{  
   "ReturnCode":"1",
   "ReturnMsg":"Successfull Transaction",
   "ReturnValue":"",
   "Data":{  
      "EmployeeName":"Admin",
      "EmployeeID":1
   }
}

This is for "Error" Response

{
    "ReturnCode": "4",
    "ReturnMsg": "Invalid Username and Password",
    "ReturnValue": "",
    "Data": {}
}

User · Answer

The RFC 7807  Problem Details for HTTP APIs is at the moment the closest thing we have to an official standard

User · Answer

For what it s worth I do this differently  A successful call just has the JSON objects  I don t need a higher level JSON object that contains a success field indicating true and a payload field that has the JSON object  I just return the appropriate JSON object with a 200 or whatever is appropriate in the 200 range for the HTTP status in the header   However  if there is an error  something in the 400 family  I return a well-formed JSON error object  For example  if the client is POSTing a User with an email address and phone number and one of these is malformed  i e  I cannot insert it into my underlying database  I will return something like this        description     Validation Failed     errors             field     phoneNumber        message     Invalid phone number              Important bits here are that the  field  property must match the JSON field exactly that could not be validated  This allows clients to know exactly what went wrong with their request  Also   message  is in the locale of the request  If both the  emailAddress  and  phoneNumber  were invalid then the  errors  array would contain entries for both  A 409  Conflict  JSON response body might look like this        description     Already Exists     errors             field     phoneNumber        message     Phone number already exists for another user              With the HTTP status code and this JSON the client has all they need to respond to errors in a deterministic way and it does not create a new error standard that tries to complete replace HTTP status codes  Note  these only happen for the range of 400 errors  For anything in the 200 range I can just return whatever is appropriate  For me it is often a HAL-like JSON object but that doesn t really matter here   The one thing I thought about adding was a numeric error code either in the the  errors  array entries or the root of the JSON object itself  But so far we haven t needed it

User · Answer

Yes there are a couple of standards  albeit some liberties on the definition of standard  that have emerged    JSON API - JSON API covers creating and updating resources as well  not just responses  JSend - Simple and probably what you are already doing  OData JSON Protocol - Very complicated  HAL - Like OData but aiming to be HATEOAS like    There are also JSON API description formats    Swagger   JSON Schema  used by swagger but you could use it stand alone   WADL in JSON RAML HAL because HATEOAS in theory is self describing

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The basic framework suggested looks fine  but the error object as defined is too limited   One often cannot use a single value to express the problem  and instead a chain of problems and causes is needed     I did a little research and found that the most common format for returning error  exceptions  is a structure of this form         success   false      error            code    400          message    main error message here          target    approx what the error came from          details                             code    23-098a                message    Disk drive has frozen up again   It needs to be replaced                target    not sure what the target is                             innererror               trace                      context                            This is the format proposed by the OASIS data standard OASIS OData and seems to be the most standard option out there  however there does not seem to be high adoption rates of any standard at this point   This format is consistent with the JSON-RPC specification   You can find the complete open source library that implements this at   Mendocino JSON Utilities    This library supports the JSON Objects as well as the exceptions   The details are discussed in my blog post on Error Handling in JSON REST API

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Assuming you question is about REST webservices design and more precisely concerning success error   I think there are 3 different types of design    Use only HTTP Status code to indicate if there was an error and try to limit yourself to the standard ones  usually it should suffice     Pros  It is a standard independent of your api  Cons  Less information on what really happened   Use HTTP Status   json body  even if it is an error   Define a uniform structure for errors  ex  code  message  reason  type  etc  and use it for errors  if it is a success then just return the expected json response    Pros  Still standard as you use the existing HTTP status codes and you return a json describing the error  you provide more information on what happened    Cons  The output json will vary depending if it is a error or success   Forget the http status  ex  always status 200   always use json and add at the root of the response a boolean responseValid and a error object  code message etc  that will be populated if it is an error otherwise the other fields  success  are populated    Pros  The client deals only with the body of the response that is a json string and ignores the status      Cons  The less standard     It s up to you to choose     Depending on the API I would choose 2 or 3  I prefer 2 for json rest apis   Another thing I have experienced in designing REST Api is the importance of documentation for each resource  url   the parameters  the body  the response  the headers etc   examples   I would also recommend you to use jersey  jax-rs implementation    genson  java json databinding library   You only have to drop genson   jersey in your classpath and json is automatically supported   EDIT    Solution 2 is the hardest to implement but the advantage is that you can nicely handle exceptions and not only business errors  initial effort is more important but you win on the long term  Solution 3 is the easy to implement on both  server side and client but it s not so nice as you will have to encapsulate the objects you want to return in a response object containing also the responseValid   error

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Following is the json format instagram is using         meta               error type    OAuthException             code   400            error message                    data                              pagination               next url                    next max id    13872296

User · Answer

There is no lawbreaking or outlaw standard other than common sense  If we abstract this like two people talking  the standard is the best way they can accurately understand each other in minimum words in minimum time  In our case   minimum words  is optimizing bandwidth for transport efficiency and  accurately understand  is the structure for parser efficiency  which ultimately ends up with the less the data  and the common the structure  so that it can go through a pin hole and can be parsed through a common scope  at least initially    Almost in every cases suggested  I see separate responses for  Success  and  Error  scenario  which is kind of ambiguity to me  If responses are different in these two cases  then why do we really need to put a  Success  flag there  Is it not obvious that the absence of  Error  is a  Success   Is it possible to have a response where  Success  is TRUE with an  Error  set  Or the way   Success  is FALSE with no  Error  set  Just one flag is not enough  I would prefer to have the  Error  flag only  because I believe there will be less  Error  than  Success    Also  should we really make the  Error  a flag  What about if I want to respond with multiple validation errors  So  I find it more efficient to have an  Error  node with each error as child to that node  where an empty  counts to zero   Error  node would denote a  Success

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For those coming later  in addition to the accepted answer that includes HAL  JSend  and JSON API  I would add a few other specifications worth looking into   JSON-LD  which is a W3C Recommendation and specifies how to build interoperable Web Services in JSON Ion Hypermedia Type for REST  which claims itself as a  quot a simple and intuitive JSON-based hypermedia type for REST quot

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I will not be as arrogant to claim that this is a standard so I will use the  I prefer  form    I prefer terse response  when requesting a list of  articles I want a JSON array of articles     In my designs I use HTTP for status report  a 200 returns just the payload    400 returns a message of what was wrong with request     message     Missing parameter   param      Return 404 if the model controler URI doesn t exist   If there was error with processing on my side  I return 501 with a message      message     Could not connect to data store      From what I ve seen quite a few REST-ish frameworks tend to be along these lines   Rationale   JSON is supposed to be a payload format  it s not a session protocol  The whole idea of verbose session-ish payloads comes from the XML SOAP world and various misguided choices that created those bloated designs  After we realized all of it was a massive headache  the whole point of REST JSON was to KISS it  and adhere to HTTP  I don t think that there is anything remotely standard in either JSend and especially not with the more verbose among them  XHR will react to HTTP response  if you use jQuery for your AJAX  like most do  you can  use try catch and done   fail   callbacks to capture errors  I can t see how encapsulating status reports in JSON is any more useful than that

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Google JSON guide Success response return data      quot data quot          quot id quot   1001       quot name quot    quot Wing quot         Error response return error      quot error quot          quot code quot   404       quot message quot    quot ID not found quot         and if your client is JS  you can use if   quot error quot  in response     to check if there is an error

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I guess a defacto standard has not really emerged  and may never   But regardless  here is my take   Successful request        status    success      data            Application-specific data would go here             message   null    Or optional success message        Failed request        status    error      data   null     or optional error payload       message    Error xyz has occurred      Advantage  Same top-level elements in both success and error cases  Disadvantage  No error code  but if you want  you can either change the status to be a  success or failure  code  -or- you can add another top-level item named  code

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Their is no agreement on the rest api response formats of big software giants - Google  Facebook  Twitter  Amazon and others  though many links have been provided in the answers above  where some people have tried to standardize the response format    As needs of the API s can differ it is very difficult to get everyone on board and agree to some format  If you have millions of users using your API  why would you change your response format   Following is my take on the response format inspired by Google  Twitter  Amazon and some posts on internet   https   github com adnan-kamili rest-api-response-format  Swagger file   https   github com adnan-kamili swagger-sample-template

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The point of JSON is that it is completely dynamic and flexible  Bend it to whatever whim you would like  because it s just a set of serialized JavaScript objects and arrays  rooted in a single node   What the type of the rootnode is is up to you  what it contains is up to you  whether you send metadata along with the response is up to you  whether you set the mime-type to application json or leave it as text plain is up to you  as long as you know how to handle the edge cases    Build a lightweight schema that you like  Personally  I ve found that analytics-tracking and mp3 ogg serving and image-gallery serving and text-messaging and network-packets for online gaming  and blog-posts and blog-comments all have very different requirements in terms of what is sent and what is received and how they should be consumed   So the last thing I d want  when doing all of that  is to try to make each one conform to the same boilerplate standard  which is based on XML2 0 or somesuch   That said  there s a lot to be said for using schemas which make sense to you and are well thought out  Just read some API responses  note what you like  criticize what you don t  write those criticisms down and understand why they rub you the wrong way  and then think about how to apply what you learned to what you need

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JSON-RPC 2 0 defines a standard request and response format  and is a breath of fresh air after working with REST APIs

[json] Is there any standard for JSON API response format?

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