I have a REST service which returns data that looks like this:
[
{ bookmark object json here },
{ bookmark object json here },
{ bookmark object json here },
...
]
My REST client class looks like this:
#Rest(rootUrl = Constants.ApiConfig.API_ROOT, converters = {MappingJackson2HttpMessageConverter.class})
public interface RestApiClient {
#Get("/bookmark/read?id={identifier}")
public BookmarkList getBookmarks(String identifier);
}
BookmarkList looks like this:
public class BookmarkList {
List<Bookmark> bookmarks;
#JsonValue
public List<Bookmark> getBookmarks() {
return bookmarks;
}
#JsonCreator
public void BookmarkList(#NotNull List<Bookmark> bookmarks) {
this.bookmarks = bookmarks;
}
}
However, when I utilize this setup, I get the following error:
Could not read JSON: Can not deserialize instance of com.whatever.entity.BookmarkList out of START_ARRAY token
What I want is something like the EventList example at https://github.com/excilys/androidannotations/wiki/Rest-API#get, but that doesn't seem to work for me out of the box.
Is there a way to get this working?
Ho... We have to update this part of documentation. The wrapper solution works but doesn't fit APIs.
If you're looking at the generated code for #Get("url") MyReturnedType testService(), you should see something like this :
return restTemplate.exchange(rootUrl.concat("url"), //
HttpMethod.GET, //
null, //
MyReturnedType.class, //
urlVariables)//
.getBody();
The returned class is injected as a parameter of exchange call. In case of generics collection (like List<MyReturnedType>), we can't inject List.class because of type checking in the return of exchange method.
However, you should be able to use this little trick in your #Rest annotated method :
public class BookmarkList extends List<Bookmark> {
}
I think I misunderstood the example at https://github.com/excilys/androidannotations/wiki/Rest-API#get. I think the array still must be wrapped inside a JSON object in that example (It'd be nice if they included example JSON data).
The data the service I'm connecting to does not return an object wrapping the array like that, so, I altered the REST client to look like this:
#Rest(rootUrl = Constants.ApiConfig.API_ROOT, converters = {MappingJackson2HttpMessageConverter.class})
public interface RestApiClient {
#Get("/bookmark/read?id={identifier}")
public ArrayNode getBookmarks(String identifier);
}
And I wrote a method in another class to iterate the ArrayNode and build the bookmarks:
public List<Bookmark> getBookmarks(Content content) {
ArrayList<Bookmark> bookmarks = new ArrayList<Bookmark>();
ArrayNode bookmarksData = apiClient.getBookmarks(content.getAcid());
for(JsonNode bookmarkData : bookmarksData) {
Bookmark bookmark = objectMapper.convertValue(bookmarkData, Bookmark.class);
bookmarks.add(bookmark);
}
return bookmarks;
}
So it's not as convenient (I had to write more code myself), but I got it working.
Related
I'm having an issue using WireMock, I've extended ResponseTransformer and implemented all required methods, it looks like this:
public class TempResponseTransformer extends ResponseTransformer {
#Override
public Response transform(Request request, Response response, FileSource fileSource,
Parameters parameters) {
return Response.Builder.like(response).but().status(404).body("1").build();
}
#Override
public boolean applyGlobally() {
return false;
}
#Override
public String getName() {
return "temp-response-transformer";
}
}
Now I want to apply this particular transformer to one of the stubs, that I wrote, stub looks like this:
private static void initTempStub() {
stubFor(post(urlPathEqualTo("/api/v1/temp"))
.withHeader("AccessToken", matching("[a-zA-Z0-9]+"))
.withHeader("CliendID", matching("[a-zA-Z0-9]+"))
.withHeader("ClientSecret", matching("[a-zA-Z0-9]+"))
.willReturn(aResponse()
.withTransformers("temp-response-transformer")));
}
When I start service and perform post calls I do see that transformer is applied, however responses actually not being transformed.
I've tried to apply transformer in config section when starting service as well, but it doesn't help.
So my question is how should I apply ReponseTransformer correctly so it would transform my responses?
Ok, think I've figured it out.
Here is an issue(?) with WireMock that I was able to figure out while looking at the internals, here is how I passed config:
new WireMockServer(wireMockConfig()
.extensions(TempResponseTransformer.class)
.options().notifier(new ConsoleNotifier(true)))
And an issue with this code is when you call options() from wireMockConfig it would create new instance of WireMockConfig, so I had to extract this config into separate piece of code like this:
var wireMockConfig = new WireMockConfiguration();
wireMockConfig
.extensions(SamplesResponseTransformer.class)
.notifier(new ConsoleNotifier(true));
I am using Spring 4 + Jackson 2 and have written a fully functional POST method using #RequestBody on a custom class. This method has no trouble unmarshalling the object.
#ResponseBody
#RequestMapping(value="store", method = RequestMethod.POST)
public ServiceResponse store(#RequestBody CustomClass list) {
...
}
// Request: { code: "A", amount: 200 }
When I attempted to add another method to handle a collection of the same class instead, my POST requests were returning with the following error.
HTTP Status 400: The request sent by the client was syntactically incorrect.
I note that this error typically occurs when the JSON submitted does not match the entity class. However, all I am doing is submitting an array of the same object instead of the object itself, which has already proven to work.
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody List<CustomClass> list) {
...
}
// Request: [{ code: "A", amount: 200 }, { code: "B", amount: 400 }]
Am I missing something here?
In Java, type information for generics is erased at runtime, so Spring sees your List<CustomClass> object as List<Object> object, thus it cannot understand how to parse it.
One of ways to solve it, you could capture the type information by creating a wrapper class for your list, like this:
public class CustomClassList extends ArrayList<CustomClass> {
}
Sergey is right that the issue is due to type erasure. Your easiest way out is to bind to an array, so
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody CustomClass[] object) {
...
}
The answer is that Spring 4 doesn't actually get rid of type erasure, contrary to what some other solutions suggest. While experimenting on debugging via manual unmarshalling, I decided to just handle that step myself instead of an implicit cast that I have no control over. I do hope someone comes along and proves me wrong, demonstrating a more intuitive solution though.
#ResponseBody
#RequestMapping(value="store-bulk", method = RequestMethod.POST)
public ServiceResponse storeBulk(#RequestBody String json) {
try {
List<CustomClass> list = new ObjectMapper().readValue(json, new TypeReference<List<CustomClass>>() { });
...
} catch (Exception e) {
...
}
}
Bonus: Right after I got this working, I bumped into this exception:
IllegalStateException: Already had POJO for id
If anyone gets this, it's because the objects in the list happen to reference some object that another item in the list already references. I could work around this since that object was identical for my entire collection, so I just removed the reference from the JSON side from all but the first object. I then added the missing references back after the JSON was unmarshalled into the List object.
Two-liner for the Java 8 users (the User object reference was the issue in my case):
User user = list.get(0).getUser();
list.stream().filter(c -> c.getUser() == null).forEach(t -> t.setUser(user));
When following http://grails.org/doc/latest/guide/webServices.html#restfulControllers in order to create RESTful webservices, I am getting 404 error when I hit anything other than index.
in my Bootstrap.groovy I have
def init = { servletContext ->
new Restaurant(title:"mourne seafood").save()
new Restaurant(title:"RBG").save()
}
in my Restaurant.groovy domain class i have
class Restaurant {
String title
static constraints = {
}
}
and in my RestaurantController.groovy REST controller I have
import grails.rest.*;
class RestaurantController extends RestfulController {
static responseFormats = ['json', 'xml']
RestaurantController() {
super(Restaurant)
}
}
I thought when reading the above link that if I call
GET <domain>/restaurant
It would call the index method, which is fine, this works, however when I call
GET <domain>/restaurant/1
I thought it should call the show method with 1 as the id? However I am getting a 404. It works correctly when I hit GET <domain>/restaurant/show/2 am I wrong in thinking that when the docs say
GET /books/${id} show in the mapping table that I shouldnt have to explicitly put show in the URL?
I know It sucks but here it is:
You need to create a generic rest controller and annotate the domain class pointing to it.
First delete the RestaurantController.groovy
Then create a BaseRestController (inside the src/main/groovy folder)
src/main/groovy/BaseRestController.groovy
import grails.rest.*;
class BaseRestController<T> extends RestfulController<T> {
BaseRestController(Class<T> domainClass) {
this(domainClass, false)
}
BaseRestController(Class<T> domainClass, boolean readOnly) {
super(domainClass, readOnly)
}
#Override
def show() {
println 'showing...'
respond queryForResource(params.id)
}
}
Ps. I just override the index action to show it works
Now you can annotate the domain class
grails-app/domain/Restaurant.groovy
import grails.rest.*
#Resource(uri='/restaurants', formats=['json', 'xml'], superClass=BaseRestController)
class Restaurant {
String title
static constraints = {
}
}
You need to specify the formats in the domain class and not in the controller. Otherwise it will be ignored and XML will be default.
I named the api endpoint as restaurants instead of the grails default restaurant
Now you can HTTP your RestFull app e.g. http://localhost:8080/restaurants/1
I seem to be experiencing a problem when using Jackson to serialize to XML. My code is below:
TEST CONTAINER
package com.test;
import java.util.ArrayList;
import com.fasterxml.jackson.annotation.JsonProperty;
public class TestContainer {
private String testContainerID;
private String testContainerMessage;
private ArrayList<TestChild> testContainerChildren;
#JsonProperty("TestContainerID")
public String getTestContainerID() {
return testContainerID;
}
#JsonProperty("TestContainerID")
public void setTestContainerID(String testContainerID) {
this.testContainerID = testContainerID;
}
#JsonProperty("TestContainerMessage")
public String getTestContainerMessage() {
return testContainerMessage;
}
#JsonProperty("TestContainerMessage")
public void setTestContainerMessage(String testContainerMessage) {
this.testContainerMessage = testContainerMessage;
}
#JsonProperty("TestContainerChildren")
public ArrayList<TestChild> getTestContainerChildren() {
return testContainerChildren;
}
#JsonProperty("TestContainerChildren")
public void setTestContainerChildren(ArrayList<TestChild> testContainerChildren) {
this.testContainerChildren = testContainerChildren;
}
}
TESTCHILD
package com.test;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonRootName;
#JsonRootName(value="TestChild")
public class TestChild {
private String testChildID;
private String testChildMessage;
#JsonProperty("TestChildID")
public String getTestChildID() {
return testChildID;
}
#JsonProperty("TestChildID")
public void setTestChildID(String testChildID) {
this.testChildID = testChildID;
}
#JsonProperty("TestChildMessage")
public String getTestChildMessage() {
return testChildMessage;
}
#JsonProperty("TestChildMessage")
public void setTestChildMessage(String testChildMessage) {
this.testChildMessage = testChildMessage;
}
}
USE
Serialization:
XmlMapper xm = new XmlMapper();
TestContainer tc = xm.readValue(sb.toString(), TestContainer.class);
Deserialization:
System.out.println(xm.writeValueAsString(tc));
tc = xm.readValue(sb.toString(), TestContainer.class);
What I'm doing is loading an XML file from a folder on the classpath and putting the contents of the file into a StringBuffer. The problem is the generated XML for the collection of objects. When writing the XML, I want something like:
<TestContainerChildren><TestChild><...(Element Details)...></TestChild></TestContainerChildren>
but I'm getting:
<TestContainerChildren><TestContainerChildren><...(Element Details)...><TestContainerChildren></TestContainerChildren>
I'm not sure what I'm missing, here. I have no problem with the JSON part of the serialization/deserialization, only the XML. I've tried using both Jackson and JAXB annotations to turn off wrapping, I have tried using the following annotations:
#JsonRootName
#JsonProperty
#JacksonXmlElementWrapper
#JacksonElement
#XmlElementWrapper
#XmlElement
I'm pretty sure this is something stupid on my part, but any help would be most appreciated.
Ok, couple of notes. First, #JsonRootName only affects name used for the root of XML document, as name implies. So it is not used for TestChild. Second, it sounds like you want to use so-called "unwrapped" output for Lists, omitting element for property that contains List elements. This is doable with:
#JacksonXmlElementWrapper(useWrapping=false)
#JsonProperty("TestContainerChildren")
public ArrayList<TestChild> getTestContainerChildren() { ... }
since default setting is to use wrapper (this is different from JAXB, where unwrapped is the default). Or, if you want to change this globally to assume unwrapped as default, you can change the defaults via XmlModule:
JacksonXmlModule module = new JacksonXmlModule();
// to default to using "unwrapped" Lists:
module.setDefaultUseWrapper(false);
XmlMapper xmlMapper = new XmlMapper(module);
Hope this helps!
I got this working by using the following annotations above the variable declaration:
#JacksonXmlElementWrapper(localName="[insert collection name]")
#JacksonXmlProperty(localName="[insert collection element name]")
This was a simple case of RTFM, as it's documented here.
I am working on a REST based interface where people get a json file. The client needs to access the file from another Domain. I use jsonp which works so far. My problem is the rendering in Grails. At the moment I use the 'as JSON' to marshalling the object:
render "${params.jsoncallback}(${user as JSON})"
The Json file getting to the client inclused all attributes, incluing the id and class, which I do not want to have in there. In case it is not jsonp, I do it this way, which works great:
render(contentType:'text/json'){
userName user.userName
userImage user.userImage
:
:
}
So how do I get the id and class attributes out of the json when rendering "user as JSON"? Any idea?
best regards,
Klaas
You can get rid of the class and id properties in the JSON result by creating a custom ObjectMarshaller.
// CustomDomainMarshaller.groovy in src/groovy:
import grails.converters.JSON;
import org.codehaus.groovy.grails.web.converters.ConverterUtil;
import org.codehaus.groovy.grails.web.converters.exceptions.ConverterException;
import org.codehaus.groovy.grails.web.converters.marshaller.ObjectMarshaller;
import org.codehaus.groovy.grails.web.json.JSONWriter;
import org.springframework.beans.BeanUtils;
public class CustomDomainMarshaller implements ObjectMarshaller<JSON> {
static EXCLUDED = ['metaClass','class','id','version']
public boolean supports(Object object) {
return ConverterUtil.isDomainClass(object.getClass());
}
public void marshalObject(Object o, JSON json) throws ConverterException {
JSONWriter writer = json.getWriter();
try {
writer.object();
def properties = BeanUtils.getPropertyDescriptors(o.getClass());
for (property in properties) {
String name = property.getName();
if(!EXCLUDED.contains(name)) {
def readMethod = property.getReadMethod();
if (readMethod != null) {
def value = readMethod.invoke(o, (Object[]) null);
writer.key(name);
json.convertAnother(value);
}
}
}
writer.endObject();
} catch (Exception e) {
throw new ConverterException("Exception in CustomDomainMarshaller", e);
}
}
}
You'll need to register in you grails-app/conf/BootStrap.groovy:
class BootStrap {
def init = { servletContext ->
grails.converters.JSON.registerObjectMarshaller(new CustomDomainMarshaller())
}
def destroy = {}
}
This should work in Grails >= 1.1
thanks for the 'quick' reply!
Man, it looks so easy in the end and took so long to figure out.
I got it working doing a map out of the values I needed and rendered them 'as json' like this:
def userProfile = user.get(randomUser)
def jsonData = [
username: userProfile.userName,
userimage: userProfile.userImage,
userstreet: userProfile.userStreet,
:
:
] as JSON
println jsonData
voila, there was the json I needed :)
It doesn't seem to me as if the JSON auto marshaller supports this.
You could use FlexJSON which allows you to exlude certain properties and wrap it into a custom Codec.
Also see here.