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Extract param data from request with spark

So I am trying to build a simple REST API and wanted to try out spark but for some reason I can't seem to extract any parameters.
Here is my endpoint for testing this:
post("/hello", (req, res) -> {
String str = req.attribute(":username"); //TODO THIS IS ALWAYS NULL!!!!!!!
System.out.println(str);
System.out.println("BODY IS WORKING:");
System.out.println(req.body().toString());
return "PANNKAKA";
});
Now if I try to make a request at http://localhost:4567/hello with the body {
"username": "bla"
}, the str variable is just null. But if I call on the body method on req, req.body().toString(); it does indeed get the body: {
"username": "bla"
} printed to the console. So the body is coming through.
This is the result in the console window:
null
BODY IS WORKING:
[
{
"username": "bla"
}
]
So how do you extract the parameter from the request's body? I have tried lots of different formatting on the param name but it just doesn't work. Been sitting with this for hours now!
I have looked at the documentation and I believe I do the correct thing:
http://sparkjava.com/documentation.html

I guess there are few ways to do this. Also, you didn't mention it by I'm assuming you send your data formatted as JSON.
I do that using an ObjectMapper (using this package com.fasterxml.jackson.databind.ObjectMapper) and a PayLoad class.
I create a simple class used as the PayLoad. It contains just fields and their getters and setters. for each value you send in the JSON you'll create the corresponding field, with exactly the same name In your case you'll have a field called username), and then the object mapper maps the JSON that you sent from the client to this class pattern. Example:
public class UserPayload {
private long id;
private String username;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
}
Then I parse the request body into this payload using the object mapper:
class SomeClass {
...
private static Object postUser(Request req, Response res) throws JSONException {
ObjectMapper mapper = new ObjectMapper();
UserPayload pl = null;
try {
pl = mapper.readValue(req.body(), UserPayload.class); // <------
} catch (JsonMappingException e1) {
...
} catch (Exception e2) {
...
}
System.out.println(pl.getUsername() + " " + pl.getId());
...
}
}
And of course register your route:
post("/hello", SomeClass::postUser);
Hope it helps.
If someone uses a simpler way, I'll be happy to hear.

You should have declared your route like the following, with the parameter :username as part of the route name:
post("/hello/:username", (req, res) -> {
String str = req.attribute(":username"); //TODO THIS IS ALWAYS NULL!!!!!!!
System.out.println(str);
System.out.println("BODY IS WORKING:");
System.out.println(req.body().toString());
return "PANNKAKA";
});
or, if what you wanted is to deal with query parameters, just take a look at this answer.

as Laercio said, if you want to get the value of this line
String str = req.attribute(":username"); //TODO THIS IS ALWAYS NULL!!!!!!!
you should declare the same var as part of your URI
post("/hello/:username" ...) ...
but if you are trying to send a JSON as Content-Type: application/json you won't get the params by that way, this only works if your send the value as Content-Type: application/x-www-form-urlencoded and then your can use req.params("username") this last is the way that ordinary HTML form send the data
Java doesn't handle very well JSON by default, you need to do some tricks to do that, or even better use Gson
If you don't want to use Gson, so you need to read the body line per line and handle by your own that data sent by application/json to get the data.

How to pass multiple parameters to Jersey POST method

I am trying to pass multiple parameters to Jersey POST method . Currently I am following below steps to pass a single parameter to Jersey POST method.
Client client = ClientBuilder.newClient();
WebTarget target= client.target("http://localhost:8080/Rest/rest/subuser").path("/insertSubUser");
SubUserBean subUserBean=new SubUserBean();
subUserBean.setIdUser(1);
subUserBean.setIdSubUserType(1);
subUserBean.setIdSubUser(15);
subUserBean.setFirstName("Haritha");
subUserBean.setLastName("Wijerathna");
subUserBean.setNumberOfDaysToEditRecord(14);
subUserBean.setUserName("haritha");
subUserBean.setPassword("hariwi88");
subUserBean.setDateCreated(Common.getSQLCurrentTimeStamp());
subUserBean.setLastUpdated(Common.getSQLCurrentTimeStamp());
target.request(MediaType.APPLICATION_JSON_TYPE).post(Entity.entity(subUserBean, MediaType.APPLICATION_JSON_TYPE));
SubUserJSONService.java
#Path("/subuser")
public class SubUserJSONService {
#POST
#Path("/insertSubUser")
#Consumes(MediaType.APPLICATION_JSON)
public String updateSubUser(SubUserBean bean){
SubUserInterface table = new SubUserTable();
String result= table.insertSubUser(bean);
return result;
}
}
Now, I want to pass parameters to following method via Jersey POST method.
public String insertHistory(List<SocialHistoryBean> list, String comment){
//my stuffs
}
Have any ideas to do above work ?
Thank you.

You can try using MultivaluedMap.Add form data and send it to the server. An example below, code is not tested just for demo/logic flow.
WebTarget webTarget = client.target("http://www.example.com/some/resource");
MultivaluedMap<List, String> formData = new MultivaluedHashMap<List, String>();
formData.add(List, "list1");
formData.add("key2", "value2");
Response response = webTarget.request().post(Entity.form(formData));
Consume this on server side something like
#Path("/uripath")
#POST -- if this is post or #GET
#Consumes("application/x-www-form-urlencoded;charset=UTF-8") or json..
#Produces("application/json")
public void methodNameHere(#FormParam("list") List<String> list1, #FormParam("key2") String val2) {
System.out.println("Here are I am");
System.out.println("list1" + list1.size);
System.out.println("val2" + val2);
}
Read more here in docs..

In case you're using Jersey 1.x, check this example on how to post multiple objects as #FormParam
Client: (pure Java):
public Response testPost(String param1, String param2) {
// Build the request string in this format:
// String request = "param1=1&param2=2";
String request = "param1=" + param1+ "&param2=" + param2;
WebClient client = WebClient.create(...);
return client.path(CONTROLLER_BASE_URI + "/test")
.post(request);
}
Server:
#Path("/test")
#POST
#Produces(MediaType.APPLICATION_JSON)
public void test(#FormParam("param1") String param1, #FormParam("param2") String param2) {
...
}

JSON data cannot be passed to the server in a List. This means that you should create a wrapper around your SocialHistoryBean class (i.e around the list that holds your objects)
#XmlRootElement(name = "uw")
public class SocialHistoryBeanWrapper implements Serializable {
private List<SocialHistoryBean> sList ;//this will hold your SocialHistoryBean instances
public SocialHistoryBeanWrapper(){
sList = new ArrayList<User>();
}
public List<User> getUsrList(){
return sList;
}
}
Your server side code will be like
#POST
#Path("/history")
#Produces(MediaType.TEXT_PLAIN)
#Consumes(MediaType.APPLICATION_JSON)
public String insertHistory( #QueryParam("comment") String comment, SocialHistoryBeanWrapper uw) {
do whatever you want with your history data
//userData.setUser(uw.getUsrList().get(0));
return comment; //just echo the string that we have sent from client
}
Note that comment is passed with #QueryParam (this means it's not part of the POST request (body) but is rather encoded in the URL string. For this to work, you can call your service as (the client code)
WebTarget target = client.target(UriBuilder.fromUri("http://localhost:8088/Rest/rest/subuser").build());
SocialHistoryBeanWrapper uw = new SocialHistoryBeanWrapper();
//just populate whatever fields you have;
uw.getUsrList().get(0).setName("Mark Foster");
uw.getUsrList().get(0).setProfession("writer");
uw.getUsrList().get(0).setId(55);
String s = target.path("history").queryParam("comment", "OK").request()
.accept(MediaType.TEXT_PLAIN).post(Entity.entity(uw, MediaType.APPLICATION_JSON), String.class);
System.out.println(s);//this prints OK

How to read JSON request body using Dropwizard

I've been writing simple dropwizard application, and everything worked fine, untill I had to change request type. As I previously got my arguments from Header, now I have to get them from the body of a JSON request. And the saddest part is - there is no complete documentation for dropwizard or any article, that would help me. Here's my code:
#Path("/actors")
#Produces("application/json")
public class ActorResource {
private final ActorDAO dao;
public ActorResource(ActorDAO dao) {
this.dao = dao;
}
#POST
#UnitOfWork
public Saying postActor(#HeaderParam("actorName") String name,#HeaderParam("actorBirthDate") String birthDate) {
Actor actor = dao.create(new Actor(name,birthDate));
return new Saying("Added : " + actor.toString());
}
Does anyone have a solution?

as requested, here's a snippet demonstrating what you want to do:
#Path("/testPost")
#Produces(MediaType.APPLICATION_JSON)
public class TestResource {
#POST
public Response logEvent(TestClass c) {
System.out.println(c.p1);
return Response.noContent().build();
}
public static class TestClass {
#JsonProperty("p1")
public String p1;
}
}
The TestClass is my body. Jersey knows right away, that it needs to parse the body into that object.
I can then curl my API doing this:
curl -v -XPOST "localhost:8085/api/testPost" -H "Content-Type: application/json" -d '{"p1":"world"}'
Jersey knows by the method parameter what to do, and by the Jackson Annotation how to treat the JSON.
Hope that helps,
Artur
Edit: For the more manual approach, you can:
In your post method, inject
#Context HttpServletRequest request
And from the injected request, write the body into a String for handling:
StringWriter writer = new StringWriter();
try {
IOUtils.copy(request.getInputStream(), writer);
} catch (IOException e) {
throw new IllegalStateException("Failed to read input stream");
}
Now use any library to map that string to whatever Object you want.

Java: Get JSON from POST with HttpServletRequest?

I'm trying to get the body of a POST request by using HttpServletRequest or UriInfo. Given a class like this one (reduced for this question):
#Path("/nodes")
#Produces({ MediaType.APPLICATION_JSON })
#Consumes({ MediaType.APPLICATION_JSON })
public class Nodes {
public NodeResource() {
//initial stuff goes here
}
/**
* gives an empty response. For testing only!
*/
#POST
#Consumes("application/json")
#Path("{id}/test-db-requests")
public Response giveNodes(#PathParam("id") final String id, #Context HttpServletRequest request, #Context UriInfo uriInfo){
//String readReq = request.getQueryString(); //would work for GET
MultivaluedMap<String,String> readParams = uriInfo.getQueryParameters();
LOG.debug("what is readParams?", readParams); //goes, but shows nothing
if (readParams != null) {
LOG.debug("null or not?"); //goes, too
for (Map.Entry<String,List<String>> entry: readParams.entrySet()) {
List<String> values = entry.getValue();
LOG.debug("params POST key: {}", entry.getKey()); // goes not
for (String val: values) {
LOG.debug("params POST values: {}", val);
}
LOG.debug("params POST next entry:::");
}
}
List<?> results = null; //currentDBRequest(id);
List<?> content = new ArrayList<>();
if (results != null) {
content = results;
}
return Response.ok(content).build();
}
}
Instead of using
MultivaluedMap<String,String> readParams = uriInfo.getQueryParameters();
//not possible at all - for GET only!? See first comment.
I also tried to use
Map<String,String[]> readParams = request.getParameterMap();
//what is about this one?
with different following code of course. But that did not work, either.
So when I fire a simple request like /nodes/546c9abc975a54c398167306/test-db-requests with the following body
{
"hi":"hello",
"green":"tree"
}
(using an JSON Array does not change anything)
and stuff in the HEADER (some informations):
Content-Type: application/json; charset=UTF-8
Accept: application/json, text/plain, */*
Connection: keep-alive
the result is disappointing, readParams is not null, but does not contain any data. Before I start to play with getReader I wanted to ask: what am I doing wrong? Is there a problem in my POST, in my Java code or in the used HttpServletRequest method(s)? Thanks!
Related questions (where I found some possible solutions), among others:
How can I grab all query parameters in Jersey JaxRS?
How to access parameters in a RESTful POST method

Alright, Jackson would actually do this for me. Just use the argument of the method, which you want to use. (See examples below.)
But you would probably not use a POST in combination with an id parameter. POST is usually used for saving fresh resources, which do not have an id (in the DB, a primary key). Moreover the path /api/{resource_name}/{id}/{some_view} would be useful for GET. Just api/{resource_name}/{id} for a GET (single entry) or a PUT (update an existing entry).
Assume you are in a resource for Pet.class. You want to catch the POSTs for this class in order to do something special with them, based on the view test-db-requests. Then do:
#POST
#Consumes("application/json")
#Path("{id}/test-db-requests")
public Response giveNodes(final String pet, #PathParam("id") final String id){
//do stuff for POST with a strigified JSON here
}
or
#POST
#Path("{id}/test-db-requests")
public Response giveNodes(final Pet pet, #PathParam("id") final String id){
//do stuff for POST with an instance of pet here (useful for non
//polymorphic resources
}

Spring catch all response types

I'm currently building a REST client which has pretty much the exact same code as in the Consuming a RESTful Web Service guide. This simple example works excellently when receiving valid JSON responses but since I'm also developing the webservice I wanted to be able to capture the raw response contents in case the response isn't valid JSON (without having to send the request twice).
So basically the guide boils down to this code:
RestTemplate restTemplate = new RestTemplate();
Page page = restTemplate.getForObject("http://graph.facebook.com/gopivotal", Page.class);
System.out.println("Name: " + page.getName());
System.out.println("About: " + page.getAbout());
System.out.println("Phone: " + page.getPhone());
System.out.println("Website: " + page.getWebsite());
And is based on this class:
package hello;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
#JsonIgnoreProperties(ignoreUnknown = true)
public class Page {
private String name;
private String about;
private String phone;
private String website;
public String getName() {
return name;
}
public String getAbout() {
return about;
}
public String getPhone() {
return phone;
}
public String getWebsite() {
return website;
}
}
Now imagine that the response is NOT valid JSON (due to a mistake in the webservice or so) or even that the response type is not application/json, how can I log the response body as plain text? I.e. how can I access the response body as plain text when this line fails:
Page page = restTemplate.getForObject("http://graph.facebook.com/gopivotal", Page.class);
PS: I came across this question - which never got answered - and though I'm not sure, I think the actual intent of that code corresponds with my question as well.

You have to implement your custom ResponseErrorHandler and plug it into your RestTemplate bean.
something like:
public class LogResponseErrorHandler implements ResponseErrorHandler {
...
#Override
public void handleError(ClientHttpResponse response) throws IOException {
logResponse(response.getBody());
}
...
}
an article about the concrete usage of ResponseErrorHandler: