Using http response headers in order to communicate server-side errors from the backend to the front-end - rest

I am working on a REST backend consumed by a javascript/ajax front-end.
I am trying to find a way to deal with invalid requests sent over by the front-end to the backend.
One of the issues I have is that HTTP status codes such as (400, 409) are not fine-grained enough to cover business logic errors such as passwords not matching (in the case of a user changing his password) or an email being unknown to the system (in the case of a user trying to signin with the application).
I am thinking of using HTTP response headers in order to communicate server-side error from the backend to the front-end.
I could for instance have an Error enum (or a class with constants) as follows:
public enum Error {
UNKNOWN_EMAIL,
PASSWORDS_DONT_MATCH,
//etc.
}
I would then use that enum in order to set the headers on the response as follows:
response.setHeader(Error.UNKNOWN_EMAIL.name(), "true");
... and deal with the error appropriately on the front-end.
Can the above architecture be improved? If so how?
Is my usage of HTTP response headers correct?
Should I use constants or enums?

Is my usage of HTTP response headers correct?
I do not think it is incorrect, however I prefer to send an error message/code directly back in the response body. This is usually more convenient for the client to access and is more explicit. As part of consuming each response, the client can check the contents of the errors (you may have multiple) and act accordingly. The following is a little contrived just to provide an example:
// ...
{
"errors": {
"username": "not found"
"password": "no match"
}
"warnings": {
"account": "expired"
}
}
// ...
The above is quite a simple approach - your JSON message can be as sophisticated as you wish but keep in mind that you should only expose the information the client needs for it to achieve its goal. This will also depend on whether you are publishing an API for 3rd parties/public consumption or whether its just for your own clients ie. your own website. If you have other parties consuming it then put some thought into it since once you publish it then you need to maintain it that way - otherwise you break any consumers.
Check out JSON API for some standardized guidance on handling errors.
Should I use constants or enums?
Since these are a related set of properties an enum is preferable over constants (I assume you are using Java).

Related

API design - Optional body in client request - Status code to return if validation fails

In our API, one of the endpoint will expect clients to provide body/payload only in certain scenario.
If the API is unable to generate a payload for given request based on the origin of the client then, we want our API to provide response with the right status code to the client, so that they know they have to provide additional information. Once the client fulfills the request with body/payload then the api will process the request as normal.
I just wanted to know is there any standard, predefined status code or procedure to implement this kind of endpoint in API design or do we have to just reject the request with some custom status code and then ask the client to implement a logic based on custom code?.
Thanks,
Vinoth
HTTP Status codes don't, nor are they intended to, map precisely against every real world error. They represent categories of error.
For example, a 404 means that the resource couldn't be found, but if your path is /customers/11/animals/5 then there are several things which could be wrong with the path. customer 11 may not have an animal 5 for example, or there may be no customer 11. There is no http response for "animal not found". Or your API may not have any calls with that pattern of URL to begin with.
You should return a status code which represents what "category" of error you have (in this case, something was not found), and the response body should contain more specific details about the error. To make things simpler, I find it helpful if the data structure is the same for a success and error (it makes parsing much easier) with a "data" field which varies per response.
Here is one example:
status code: 404 not found
body: {
"messageDetailCode" :"CustomerNotFound",
"messageDetail" : "Customer not found",
"data" : null
}
Further reading:
What's an appropriate HTTP status code to return by a REST API service for a validation failure?

Different response for same API but different method (GET and POST)

I think this is a classic and typical question but I didn't find its answer.
In my knowledge, the POST method is used to send data to the server with request parameter in message body to make it secure. And GET method is to retrieve data with parameters in the URL.
But what I didn't understand is how the same api may have different behavior by just changing the method.
Here is an example. I use SoapUI 5.5.0, this is the link of the api: https://reqres.in/api/users/1
when I use GET method I get this:
{
"data": {
"id": 1,
"email": "george.bluth#reqres.in",
"first_name": "George",
"last_name": "Bluth",
"avatar": "https://s3.amazonaws.com/uifaces/faces/twitter/calebogden/128.jpg"
}
}
and by changing only the method to POST, I get this:
{
"id": "244",
"createdAt": "2020-02-27T14:30:32.100Z"
}
(the id and date changes each time)
as described in this link https://reqres.in/ that it is creating an instance and we can add parameters..
BUT, can any one explain how is it technically possible to have different behavior with different methods on the same URL.
In my knowledge, the POST method is used to send data to the server with request parameter in message body to make it secure. And GET method is to retrieve data with parameters in the URL.
That's probably getting in your way.
HTTP Requests are messages; each message starts with a request-line
method SP request-target SP HTTP-version CRLF
The request-target identifies the target resource upon which to apply the request
The method token indicates the request method to be performed on the target resource.
You can think of it being like a function call
GET(target-resource)
POST(target-resource, message-body)
Or equivalently you can think of the resources as objects that share an understanding of message semantics
target-resource.GET()
target-resource.POST(message-body)
But what I didn't understand is how the same api may have different behavior by just changing the method.
The same way that an api can exhibit different behavior by just changing the request-target.
In HTTP, the request-line is literally human readable text that the server will parse. Having parsed the request-line, the server program can then branch to whatever code it wants to use to do the work, based on the values it found in the message.
In many frameworks (Spring, Rails) the branching logic is provided by the framework code; your bespoke handlers only need to be correctly registered and the framework ensures that each request is forwarded to the correct handler.
how is it technically possible to have different behavior with
different methods on the same URL
for the technical possibility, you can look at the spring framework's answer to this.
You can have a controller that is accessible on a single url but can contacted in four says, GET, PUT, POST, DELETE. To do this, Spring provides the annotations #GetMapping, #PostMapping, #PutMapping, #DeleteMapping.
All the requests are sent to the same url and Spring works out which method to call based on the verb.
In Restful APIs, verbs have very important meaning.
GET: Retrieve data
POST: Create a new entity with the request's body
PUT: Replace an entity with the request's body
PATCH: Update some properties of an entity with the request's body. A.K.A. Partial update
In your case, changing the verb from get to post has the effect of creating a new entity with ID 1. That's why you get a response with the newly created ID and a createdAt timestamp.

REST endpoint: how to proper design an action on a resource?

I have the resource /contracts with the following structure:
{
name: "Contract name",
signedAt: 123213231,
// etc.
}
While basic CRUD operations are well clear (GET /contracts, GET /contracts/{id}, POST /contracts, etc.) some doubts come when I have to do some concrete actions on the resource.
One of these actions is the following:
sign: means the contract is signed, so the signedAt date will need to be updated with the moment (date-time) the contract was signed.
So far I've been thinking about these different approaches:
PATCH-ing the resource
This approach will mean having the following endpoint method:
PATCH /contracts/{id}
and just posting the signedAt date { signedAt: 123213231 } meaning that after this the contract will be signed.
What I don't like about this approach is that the signature date comes from the client, I was thinking that having this date initialized on the backend side whenever a contract is signed could be better and more consistent.
Totally discarded, as the signedAt date should be set on the server
side exactly at the moment the sign is done.
POST-ing a new resource
This approach will mean having the signature action as a resource:
POST /contracts/{id}/sign
with an empty body in this case as we don't need to pass anything else so, once it is posted, the backend side would be the responsible for having the signature date initialized.
POST-ing the resource using 'action'
Similar to the previous approach, in this case I would use a query parameter called action on the contract resource:
POST /contracts/{idContract}?action=sign
also with an empty body where ?action=sign. Like in the previous approach, once posted the backend side would be the responsible for having the signature date initialized.
Questions
What would be the proper way to have this designed at a REST API level?
Is any of the approaches above close to a good design or not?
Would I need to modify any of the approaches?
Is there any better alternative?
I have designed a few rest APIs myself but I am not a restful evangelist so my answer might not be the best. I would suggest some of the following:
Create a custom converter for date values in your rest service that accepts date AND other specific fields. If you checkGoogle reporting APIs for example they allow you to use specific date range and also CURRENT_WEEK, CURRENT_MONTH etc. So you can add such specific value and use it. For example PATCH signedAt=CURRENT_DATE and the API handles that properly.
Add a boolean signed field to the resource. Do a POST or PATCH with signed=true. This way you will be able to eventually query only signed resources easily ;) Also it might be the case that people care only about if it is signed than when it was signed
I wouldn't use ?action=sign or /contracts/{id}/sign because these are not RESTFUL and even if you do use GET and POST you would use them in a way to create a workaround in order to implement actions in your design which shouldn't have actions
just posting the signedAt date { signedAt: 123213231 } meaning that after this the contract will be signed.
On HTTP Patch
The set of changes is represented in a format called a "patch document" identified by a media type.
Rather than rolling your own bespoke media type, you might want to consider whether one of the standard formats is suitable.
For example: JSON Patch.
Content-Type: application/json-patch+json
[ { "op": "replace", "path": "signedAt", "value": 123213231 }
JSON Merge Patch is another reasonable option
Content-Type: application/merge-patch+json
{ signedAt: 123213231 }
From what I can see, the primary difference is that JSON Patch provides a test operation which gives you finer grain control than simply relying upon validators
But you are absolutely right - PATCH gives the client code authority to specify the time value. If that's not appropriate for your use case, then PATCH is the wrong tool in the box.
POST /contracts/{id}/sign
POST /contracts/{idContract}?action=sign
As far as REST/HTTP are concerned, these two choices are equivalent -- you are updating the state of one resource by sending an unsafe request to a different resource. There are some mild differences in how these spellings act when resolving references, but as request-targets, it doesn't make a difference to the client.
An option that you seem to have overlooked:
POST /contracts/{id}
action=sign
This has the advantage that, when successful, you get cache invalidation for free.
In a hypermedia API, the flow might go something like this: the client would GET the resource; because the resource hasn't been signed yet, the representation could include a form, with a "sign" button on it. The action on the form would be /contracts/{id}. The consumer "signs" the contract by submitting the form -- the agent gathers up the information described by the form, encodes it into the request body, and then posts the request to the server. The server responds success, and the client's cache knows to invalidate the previously fetched copy of the resource.

Proper way to convey error messages during calls to a REST service?

I'm writing a REST based web service, and I'm trying to figure out the best way to handle error conditions.
Currently the service is returning HTTP Errors, such as Bad Request, but how can I return extra information to give developers using the web service an idea what they're doing wrong?
For example: creating a user with a null username returns an error of Bad Request. How can I add that the error was caused by a null username parameter?
According to the HTTP spec, the text that comes after the three digit response code, the "Reason-Phrase", can only be replaced with a logical equivalent. So you can't respond with 400 null user and expect anything useful to happen. Indeed, The client is not required to examine or display the Reason- Phrase.
In general, the HTTP response entity (typically the page that accompanies the response) should contain information useful to the client to guide them forward, even when the response is an error. On the web, most such errors are HTML, and are devoid of machine readable information, but most browsers do show the error to the user (and SO's error page is pretty good!).
So for a primarily machine readable resource you have two options:
Pass a human readable message anyway. Return 400 Bad Request with a HTML response, which the client may opt to show to the user. It's dead easy but it's a bit like throwing an unchecked exception, it passes all the hard work to the client, or indeed the end user.
Allow clients to recover. Return 400 Bad Request with a machine readable response which is part of your API, so clients can recover from known error conditions. This is harder, like throwing a checked exception, it becomes part of the API, and it allows clients to recover gracefully if they want to.
You could even make the server support both scenarios by defining a media type for the machie readable error recovery document, and allow clients to "accept" them: Accept: application/atom+xml, application/my.proprietary.errors+json
Clients that forget the mandatory field can opt in to getting machine readable errors or human readable errors by choosing to Accepting the error media type.
It's stated in the HTTP spec that most error codes should return some basic text that gives a clarification of why the error is being returned. The basic Java Servlet Spec defines the HttpServletResponse.sendError(int Code, String message) for this purpose.
String desc = "my Description";
throw new WebApplicationException(Response.status(Status.BAD_REQUEST).entity(desc).type("text/plain").build());

HTTP GET with request body

I'm developing a new RESTful webservice for our application.
When doing a GET on certain entities, clients can request the contents of the entity.
If they want to add some parameters (for example sorting a list) they can add these parameters in the query string.
Alternatively I want people to be able to specify these parameters in the request body.
HTTP/1.1 does not seem to explicitly forbid this. This will allow them to specify more information, might make it easier to specify complex XML requests.
My questions:
Is this a good idea altogether?
Will HTTP clients have issues with using request bodies within a GET request?
https://www.rfc-editor.org/rfc/rfc2616
Roy Fielding's comment about including a body with a GET request.
Yes. In other words, any HTTP request message is allowed to contain a message body, and thus must parse messages with that in mind. Server semantics for GET, however, are restricted such that a body, if any, has no semantic meaning to the request. The requirements on parsing are separate from the requirements on method semantics.
So, yes, you can send a body with GET, and no, it is never useful to do so.
This is part of the layered design of HTTP/1.1 that will become clear again once the spec is partitioned (work in progress).
....Roy
Yes, you can send a request body with GET but it should not have any meaning. If you give it meaning by parsing it on the server and changing your response based on its contents, then you are ignoring this recommendation in the HTTP/1.1 spec, section 4.3:
...if the request method does not include defined semantics for an entity-body, then the message-body SHOULD be ignored when handling the request.
And the description of the GET method in the HTTP/1.1 spec, section 9.3:
The GET method means retrieve whatever information ([...]) is identified by the Request-URI.
which states that the request-body is not part of the identification of the resource in a GET request, only the request URI.
Update
The RFC2616 referenced as "HTTP/1.1 spec" is now obsolete. In 2014 it was replaced by RFCs 7230-7237. Quote "the message-body SHOULD be ignored when handling the request" has been deleted. It's now just "Request message framing is independent of method semantics, even if the method doesn't define any use for a message body" The 2nd quote "The GET method means retrieve whatever information ... is identified by the Request-URI" was deleted. - From a comment
From the HTTP 1.1 2014 Spec:
A payload within a GET request message has no defined semantics; sending a payload body on a GET request might cause some existing implementations to reject the request.
While you can do that, insofar as it isn't explicitly precluded by the HTTP specification, I would suggest avoiding it simply because people don't expect things to work that way. There are many phases in an HTTP request chain and while they "mostly" conform to the HTTP spec, the only thing you're assured is that they will behave as traditionally used by web browsers. (I'm thinking of things like transparent proxies, accelerators, A/V toolkits, etc.)
This is the spirit behind the Robustness Principle roughly "be liberal in what you accept, and conservative in what you send", you don't want to push the boundaries of a specification without good reason.
However, if you have a good reason, go for it.
You will likely encounter problems if you ever try to take advantage of caching. Proxies are not going to look in the GET body to see if the parameters have an impact on the response.
Elasticsearch accepts GET requests with a body. It even seems that this is the preferred way: Elasticsearch guide
Some client libraries (like the Ruby driver) can log the cry command to stdout in development mode and it is using this syntax extensively.
Neither restclient nor REST console support this but curl does.
The HTTP specification says in section 4.3
A message-body MUST NOT be included in a request if the specification of the request method (section 5.1.1) does not allow sending an entity-body in requests.
Section 5.1.1 redirects us to section 9.x for the various methods. None of them explicitly prohibit the inclusion of a message body. However...
Section 5.2 says
The exact resource identified by an Internet request is determined by examining both the Request-URI and the Host header field.
and Section 9.3 says
The GET method means retrieve whatever information (in the form of an entity) is identified by the Request-URI.
Which together suggest that when processing a GET request, a server is not required to examine anything other that the Request-URI and Host header field.
In summary, the HTTP spec doesn't prevent you from sending a message-body with GET but there is sufficient ambiguity that it wouldn't surprise me if it was not supported by all servers.
GET, with a body!?
Specification-wise you could, but, it's not a good idea to do so injudiciously, as we shall see.
RFC 7231 §4.3.1 states that a body "has no defined semantics", but that's not to say it is forbidden. If you attach a body to the request and what your server/app makes out of it is up to you. The RFC goes on to state that GET can be "a programmatic view on various database records". Obviously such view is many times tailored by a large number of input parameters, which are not always convenient or even safe to put in the query component of the request-target.
The good: I like the verbiage. It's clear that one read/get a resource without any observable side-effects on the server (the method is "safe"), and, the request can be repeated with the same intended effect regardless of the outcome of the first request (the method is "idempotent").
The bad: An early draft of HTTP/1.1 forbade GET to have a body, and - allegedly - some implementations will even up until today drop the body, ignore the body or reject the message. For example, a dumb HTTP cache may construct a cache key out of the request-target only, being oblivious to the presence or content of a body. An even dumber server could be so ignorant that it treats the body as a new request, which effectively is called "request smuggling" (which is the act of sending "a request to one device without the other device being aware of it" - source).
Due to what I believe is primarily a concern with inoperability amongst implementations, work in progress suggests to categorize a GET body as a "SHOULD NOT", "unless [the request] is made directly to an origin server that has previously indicated, in or out of band, that such a request has a purpose and will be adequately supported" (emphasis mine).
The fix: There's a few hacks that can be employed for some of the problems with this approach. For example, body-unaware caches can indirectly become body-aware simply by appending a hash derived from the body to the query component, or disable caching altogether by responding a cache-control: no-cache header from the server.
Alas when it comes to the request chain, one is often not in control of- or even aware, of all present and future HTTP intermediaries and how they will deal with a GET body. That's why this approach must be considered generally unreliable.
But POST, is not idempotent!
POST is an alternative. The POST request usually includes a message body (just for the record, body is not a requirement, see RFC 7230 §3.3.2). The very first use case example from RFC 7231 (§4.3.3) is "providing a block of data [...] to a data-handling process". So just like GET with a body, what happens with the body on the back-end side is up to you.
The good: Perhaps a more common method to apply when one wish to send a request body, for whatever purpose, and so, will likely yield the least amount of noise from your team members (some may still falsely believe that POST must create a resource).
Also, what we often pass parameters to is a search function operating upon constantly evolving data, and a POST response is only cacheable if explicit freshness information is provided in the response.
The bad: POST requests are not defined as idempotent, leading to request retry hesitancy. For example, on page reload, browsers are unwilling to resubmit an HTML form without prompting the user with a nonreadable cryptic message.
The fix: Well, just because POST is not defined to be idempotent doesn't mean it mustn't be. Indeed, RFC 7230 §6.3.1 writes: "a user agent that knows (through design or configuration) that a POST request to a given resource is safe can repeat that request automatically". So, unless your client is an HTML form, this is probably not a real problem.
QUERY is the holy grail
There's a proposal for a new method QUERY which does define semantics for a message body and defines the method as idempotent. See this.
Edit: As a side-note, I stumbled into this StackOverflow question after having discovered a codebase where they solely used PUT requests for server-side search functions. This were their idea to include a body with parameters and also be idempotent. Alas the problem with PUT is that the request body has very precise semantics. Specifically, the PUT "requests that the state of the target resource be created or replaced with the state [in the body]" (RFC 7231 §4.3.4). Clearly, this excludes PUT as a viable option.
You can either send a GET with a body or send a POST and give up RESTish religiosity (it's not so bad, 5 years ago there was only one member of that faith -- his comments linked above).
Neither are great decisions, but sending a GET body may prevent problems for some clients -- and some servers.
Doing a POST might have obstacles with some RESTish frameworks.
Julian Reschke suggested above using a non-standard HTTP header like "SEARCH" which could be an elegant solution, except that it's even less likely to be supported.
It might be most productive to list clients that can and cannot do each of the above.
Clients that cannot send a GET with body (that I know of):
XmlHTTPRequest Fiddler
Clients that can send a GET with body:
most browsers
Servers & libraries that can retrieve a body from GET:
Apache
PHP
Servers (and proxies) that strip a body from GET:
?
What you're trying to achieve has been done for a long time with a much more common method, and one that doesn't rely on using a payload with GET.
You can simply build your specific search mediatype, or if you want to be more RESTful, use something like OpenSearch, and POST the request to the URI the server instructed, say /search. The server can then generate the search result or build the final URI and redirect using a 303.
This has the advantage of following the traditional PRG method, helps cache intermediaries cache the results, etc.
That said, URIs are encoded anyway for anything that is not ASCII, and so are application/x-www-form-urlencoded and multipart/form-data. I'd recommend using this rather than creating yet another custom json format if your intention is to support ReSTful scenarios.
I put this question to the IETF HTTP WG. The comment from Roy Fielding (author of http/1.1 document in 1998) was that
"... an implementation would be broken to do anything other than to parse and discard that body if received"
RFC 7213 (HTTPbis) states:
"A payload within a GET request message has no defined semantics;"
It seems clear now that the intention was that semantic meaning on GET request bodies is prohibited, which means that the request body can't be used to affect the result.
There are proxies out there that will definitely break your request in various ways if you include a body on GET.
So in summary, don't do it.
From RFC 2616, section 4.3, "Message Body":
A server SHOULD read and forward a message-body on any request; if the
request method does not include defined semantics for an entity-body,
then the message-body SHOULD be ignored when handling the request.
That is, servers should always read any provided request body from the network (check Content-Length or read a chunked body, etc). Also, proxies should forward any such request body they receive. Then, if the RFC defines semantics for the body for the given method, the server can actually use the request body in generating a response. However, if the RFC does not define semantics for the body, then the server should ignore it.
This is in line with the quote from Fielding above.
Section 9.3, "GET", describes the semantics of the GET method, and doesn't mention request bodies. Therefore, a server should ignore any request body it receives on a GET request.
Which server will ignore it? – fijiaaron Aug 30 '12 at 21:27
Google for instance is doing worse than ignoring it, it will consider it an error!
Try it yourself with a simple netcat:
$ netcat www.google.com 80
GET / HTTP/1.1
Host: www.google.com
Content-length: 6
1234
(the 1234 content is followed by CR-LF, so that is a total of 6 bytes)
and you will get:
HTTP/1.1 400 Bad Request
Server: GFE/2.0
(....)
Error 400 (Bad Request)
400. That’s an error.
Your client has issued a malformed or illegal request. That’s all we know.
You do also get 400 Bad Request from Bing, Apple, etc... which are served by AkamaiGhost.
So I wouldn't advise using GET requests with a body entity.
According to XMLHttpRequest, it's not valid. From the standard:
4.5.6 The send() method
client . send([body = null])
Initiates the request. The optional argument provides the request
body. The argument is ignored if request method is GET or HEAD.
Throws an InvalidStateError exception if either state is not
opened or the send() flag is set.
The send(body) method must run these steps:
If state is not opened, throw an InvalidStateError exception.
If the send() flag is set, throw an InvalidStateError exception.
If the request method is GET or HEAD, set body to null.
If body is null, go to the next step.
Although, I don't think it should because GET request might need big body content.
So, if you rely on XMLHttpRequest of a browser, it's likely it won't work.
If you really want to send cachable JSON/XML body to web application the only reasonable place to put your data is query string encoded with RFC4648: Base 64 Encoding with URL and Filename Safe Alphabet. Of course you could just urlencode JSON and put is in URL param's value, but Base64 gives smaller result. Keep in mind that there are URL size restrictions, see What is the maximum length of a URL in different browsers? .
You may think that Base64's padding = character may be bad for URL's param value, however it seems not - see this discussion: http://mail.python.org/pipermail/python-bugs-list/2007-February/037195.html . However you shouldn't put encoded data without param name because encoded string with padding will be interpreted as param key with empty value.
I would use something like ?_b64=<encodeddata>.
I wouldn't advise this, it goes against standard practices, and doesn't offer that much in return. You want to keep the body for content, not options.
You have a list of options which are far better than using a request body with GET.
Let' assume you have categories and items for each category. Both to be identified by an id ("catid" / "itemid" for the sake of this example). You want to sort according to another parameter "sortby" in a specific "order". You want to pass parameters for "sortby" and "order":
You can:
Use query strings, e.g.
example.com/category/{catid}/item/{itemid}?sortby=itemname&order=asc
Use mod_rewrite (or similar) for paths:
example.com/category/{catid}/item/{itemid}/{sortby}/{order}
Use individual HTTP headers you pass with the request
Use a different method, e.g. POST, to retrieve a resource.
All have their downsides, but are far better than using a GET with a body.
What about nonconforming base64 encoded headers? "SOMETHINGAPP-PARAMS:sdfSD45fdg45/aS"
Length restrictions hm. Can't you make your POST handling distinguish between the meanings? If you want simple parameters like sorting, I don't see why this would be a problem. I guess it's certainty you're worried about.
I'm upset that REST as protocol doesn't support OOP and Get method is proof. As a solution, you can serialize your a DTO to JSON and then create a query string. On server side you'll able to deserialize the query string to the DTO.
Take a look on:
Message-based design in ServiceStack
Building RESTful Message Based Web Services with WCF
Message based approach can help you to solve Get method restriction. You'll able to send any DTO as with request body
Nelibur web service framework provides functionality which you can use
var client = new JsonServiceClient(Settings.Default.ServiceAddress);
var request = new GetClientRequest
{
Id = new Guid("2217239b0e-b35b-4d32-95c7-5db43e2bd573")
};
var response = client.Get<GetClientRequest, ClientResponse>(request);
as you can see, the GetClientRequest was encoded to the following query string
http://localhost/clients/GetWithResponse?type=GetClientRequest&data=%7B%22Id%22:%2217239b0e-b35b-4d32-95c7-5db43e2bd573%22%7D
IMHO you could just send the JSON encoded (ie. encodeURIComponent) in the URL, this way you do not violate the HTTP specs and get your JSON to the server.
For example, it works with Curl, Apache and PHP.
PHP file:
<?php
echo $_SERVER['REQUEST_METHOD'] . PHP_EOL;
echo file_get_contents('php://input') . PHP_EOL;
Console command:
$ curl -X GET -H "Content-Type: application/json" -d '{"the": "body"}' 'http://localhost/test/get.php'
Output:
GET
{"the": "body"}
Even if a popular tool use this, as cited frequently on this page, I think it is still quite a bad idea, being too exotic, despite not forbidden by the spec.
Many intermediate infrastructures may just reject such requests.
By example, forget about using some of the available CDN in front of your web site, like this one:
If a viewer GET request includes a body, CloudFront returns an HTTP status code 403 (Forbidden) to the viewer.
And yes, your client libraries may also not support emitting such requests, as reported in this comment.
If you want to allow a GET request with a body, a way is to support POST request with header "X-HTTP-Method-Override: GET". It is described here : https://en.wikipedia.org/wiki/List_of_HTTP_header_fields. This header means that while the method is POST, the request should be treated as if it is a GET. Body is allowed for POST, so you're sure nobody willl drop the payload of your GET requests.
This header is oftenly used to make PATCH or HEAD requests through some proxies that do not recognize those methods and replace them by GET (always fun to debug!).
An idea on an old question:
Add the full content on the body, and a short hash of the body on the querystring, so caching won't be a problem (the hash will change if body content is changed) and you'll be able to send tons of data when needed :)
Create a Requestfactory class
import java.net.URI;
import javax.annotation.PostConstruct;
import org.apache.http.client.methods.HttpEntityEnclosingRequestBase;
import org.apache.http.client.methods.HttpUriRequest;
import org.springframework.http.HttpMethod;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.client.RestTemplate;
#Component
public class RequestFactory {
private RestTemplate restTemplate = new RestTemplate();
#PostConstruct
public void init() {
this.restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestWithBodyFactory());
}
private static final class HttpComponentsClientHttpRequestWithBodyFactory extends HttpComponentsClientHttpRequestFactory {
#Override
protected HttpUriRequest createHttpUriRequest(HttpMethod httpMethod, URI uri) {
if (httpMethod == HttpMethod.GET) {
return new HttpGetRequestWithEntity(uri);
}
return super.createHttpUriRequest(httpMethod, uri);
}
}
private static final class HttpGetRequestWithEntity extends HttpEntityEnclosingRequestBase {
public HttpGetRequestWithEntity(final URI uri) {
super.setURI(uri);
}
#Override
public String getMethod() {
return HttpMethod.GET.name();
}
}
public RestTemplate getRestTemplate() {
return restTemplate;
}
}
and #Autowired where ever you require and use, Here is one sample code GET request with RequestBody
#RestController
#RequestMapping("/v1/API")
public class APIServiceController {
#Autowired
private RequestFactory requestFactory;
#RequestMapping(method = RequestMethod.GET, path = "/getData")
public ResponseEntity<APIResponse> getLicenses(#RequestBody APIRequest2 APIRequest){
APIResponse response = new APIResponse();
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
Gson gson = new Gson();
try {
StringBuilder createPartUrl = new StringBuilder(PART_URL).append(PART_URL2);
HttpEntity<String> entity = new HttpEntity<String>(gson.toJson(APIRequest),headers);
ResponseEntity<APIResponse> storeViewResponse = requestFactory.getRestTemplate().exchange(createPartUrl.toString(), HttpMethod.GET, entity, APIResponse.class); //.getForObject(createLicenseUrl.toString(), APIResponse.class, entity);
if(storeViewResponse.hasBody()) {
response = storeViewResponse.getBody();
}
return new ResponseEntity<APIResponse>(response, HttpStatus.OK);
}catch (Exception e) {
e.printStackTrace();
return new ResponseEntity<APIResponse>(response, HttpStatus.INTERNAL_SERVER_ERROR);
}
}
}