I have an API the returns a standard reply for all requests that gets parsed by gson/retrofit.
public class ServerReply<T> {
#Expose
private String status;
#Expose
private T data;
#Expose
private String message;
}
I have an interface for Retrofit that will return a list of users inside of serverReply.
public interface Test {
#POST("/Test")
void runTest(#Body Body body, Callback<ServerReply<List<User>>> response);
}
I would like to get a different list of objects depending on the content of the body. Is it possible to use templating/generics to accomplish this?(see below)
public interface Test<T> {
#POST("/Test")
void runTest(#Body Body body, Callback<ServerReply<List<T>>> response);
}
No, but it's a Java limitation not a missing Retrofit feature. Due to type erasure there is no way for Retrofit to resolve what the type variable T actually is to pass to the deserializer without a concrete class.
Related
Here is a minimal version of code that I want to test:
#Service
public class Ver {
#Autowired
private DHClient dhclient;
#Autowired
private DHUrlService dhUrlService;
public String getLVersion(String LRversion)
{
String vers=dhclient.get(dhUrlService.getUrl());
return getVersion(vers, LRversion);
}
}
Now the problem with testing this is that. dhclient is autowired inside the Ver class.
The get function makes an HTTP Get request and fetches a response.
I want the test case to actually make the dhclient.get call and return the result.
Any ideas on how to go about testing this?
How do I test that getLVer(String lrVersion) returns null when "test" is passed as the argument?
#Service
public class DHClient {
#Value("${clientId}")
private String clientId;
private HttpClient httpClient;
public String get(String URL){
HttpRequest request// build the HTTP request
HttpResponse<String> response = httpCient.send(request,HttpResponse.BodyHandlers.ofString());
return response.body()
}
}
the above is the code of the DHClient. Since I want to make an actual GET call using the get function. Probably mocking the object is not a good idea. The alternative would be to create an actual object. But this has fields like clientId and httpClient which are initialized by Spring. I am not sure how to create an actual object for this.
I have a complex object like this:
public class ComplexObject {
private String a;
private String b;
...
private String z;
//getters and setters
}
I want to call a web service that receives all the complex object fields: http://localhost:8080/api/some_service?a=something&b=something&...&z=something
Is there any way to pass a ComplexObject to RestTemplate and have the work done automatically or I have to do the manual mapping by myself?
Thanks!
YES! there is a way to pass complete complex object to make the service call and then for sure it can be achieved automatically.
And for this you have to alter the way you send this complexObject and have to use HTTP POST (highly recommended ), as:
public HttpStatus send()
{
ComplexObject complexObj = getYourFilledObject();
ResponseEntity<HttpStatus> response = restTemplate.postForEntity(ROOT_URI, complexObj, HttpStatus.class);
return response;
}
And if not and GET is the only option then unfortunately you have to send as you’re. Because at the end of the day either you use rest templates ‘s function which intake params map or you create your own URI with params, it is the same HTTP GET and you have to achieve programmatically.
For examples & illustration you can visit here and best reference will be spring resttemplate doc
I am looking for transportation layer for gwt. I would like to create ajax request using generic method, f.e this is my DAO/service:
public class GenericDao<T extends GenericModel<T>> {
private Logger logger = LoggerFactory.getLogger(this.getClass().getCanonicalName());
#Transient protected Class<T> entityClass;
public GenericDao() {
super();
}
public GenericDao(Class<? extends GenericModel<T>> clazz) {
this.entityClass = (Class<T>) clazz;
}
public T getBy(Long id) {
return JPA.em().find(entityClass, id);
}
public List<GenericModel<T>> get() {
logger.error("trying to get data from db");
return getList();
}
public List<GenericModel<T>> getList() {
return JPA.em().createQuery("FROM " + entityClass.getSimpleName()).getResultList();
}
public void save(GenericModel<T> entityClass) {
JPA.em().getTransaction().begin();
JPA.em().persist(entityClass);
JPA.em().getTransaction().commit();
}
public void update(T entityClass) {
JPA.em().getTransaction().begin();
JPA.em().merge(entityClass);
JPA.em().getTransaction().commit();
}
public void delete(T entityClass) {
JPA.em().getTransaction().begin();
JPA.em().remove(entityClass);
JPA.em().getTransaction().commit();
}
}
GenericModel/Entity:
#MappedSuperclass
public class GenericModel<T extends GenericModel<T>> implements Identifiable, Versionable {
#Transient
protected Class<T> entityClass;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Version
private Integer version;
// setter & getter
#Override
public Long getId() {return id;}
public void setId(Long id) {this.id = id;}
#Override
public Integer getVersion() {return version;}
public void setVersion(Integer version) {this.version = version;}
// constructor
public GenericModel() {
Class<?> obtainedClass = getClass();
Type genericSuperclass = null;
for (;;) {
genericSuperclass = obtainedClass.getGenericSuperclass();
if (genericSuperclass instanceof ParameterizedType) {
break;
}
obtainedClass = obtainedClass.getSuperclass();
}
ParameterizedType genericSuperclass_ = (ParameterizedType) genericSuperclass;
try {
entityClass = ((Class) ((Class) genericSuperclass_
.getActualTypeArguments()[0]));
} catch (ClassCastException e) {
entityClass = guessEntityClassFromTypeParametersClassTypedArgument();
}
}
public GenericModel(Long id) {
this();
this.id = id;
}
}
I am looking for mechanism that will allow me to use this generic service for all models on client side (each db entity have id- so I would like to downloads using ajax all my Entities this way, so I should have only one generic method for that on client side).
I've already checked:
GWT-RPC
RequestFactory
RestyGWT
But none of them support this feature.
I've found here:
https://www.mail-archive.com/google-web-toolkit#googlegroups.com/msg100095.html
information that: gwt-jackson supports generics and polymorphism. Unfortunately I didn't found any working example that. Can someone help, give an example, approved that information?
All entities have id and version parameter. So I would like to have one metod on client side RF that will allow me to get from server(service/dao/whatever) that entity by id- like this: Request getBy(Long id); But unfortunatelly I can't make it work. I like the RF way, so I've tried it first. Generally I don't wonna repeat code for downloading entity/proxy by id.
For better understanding, please look also on:
RequestFactory client-side inheritance of typed class with generics
I'm confused as to why you think RPC can't handle generics - according to your link, it can, but RestyGWT cannot. Granted, none of your JPA references make any sense in GWT, but those would live in a DAO on the server, not in the entity/model class themselves, or at least not in the client version. If you had a RPC method that returned T where <T extends GenericModel<T>>, then you would have serializers for every possible GenericModel<?> subtype, and any/all that are gwt-compatible could be sent over the wire.
Edit from update to question:
Your GenericModel class uses features of Java that cannot work in GWT, such as reflection. This cannot be compiled to GWT, since the compiler relies on removing reflection information to minimize your compiled size - leaving in general reflection information means leaving in details about all classes and members, even ones that it can't statically prove are in use, since some reflection might make use of them.
If there is a way to phrase your model object in a way that just deals with the data at hand, focus on that. Otherwise consider a DTO which is just the data to send over the wire - I'm not sure how you would plan to use the entityClass field on the client, or why that would be important to read from the superclass's generics instead of just using getClass().
RequestFactory will have a hard time dealing with generics - unlike RPC (and possibly RestyGWT) it cannot handle polymorphism the way you want, but will instead only send the fields for the declared type, not any arbitrary subtype. RPC will actually send the instance if it is something that the client can handle.
This works fine
In my Spring-based application, I have set up a HTTP-based REST endpoint. This endpoint "speaks" JSON:
#Controller
public class HttpRestController implements RestController {
#Override
#RequestMapping(value = "/users/{user}", method = RequestMethod.GET)
#ResponseBody
public getUser(#PathVariable User user) {
User jsonFriendlyUser = new JacksonAnnotatedUser(user);
return jsonFriendlyUser;
}
}
As these JSON payloads have to follow unusual naming conventions, I used annotations such as #JsonRootName and #JsonProperty to customize the serialized property names:
#JsonRootName("uussaaar")
public class JacksonAnnotatedUser implements User {
//...
public int getId() {
return id;
}
#JsonProperty("naammee")
public String getName() {
return name;
}
#JsonSerialize(using = FriendsJsonSerializer.class )
public Set<User> getFriends() {
return friends;
}
#JsonIgnore
public String getUnimportantProperty() {
return unimportantProperty;
}
}
With this custom JSON metadata, querying /users/123 via HTTP returns the following JSON payload:
{"uussaaar":
{
"id":123,
"naammee":"Charlie",
"friends": [456, 789]
}
}
The following doesn't work as expected
Now I am playing around with Spring's WebSocket support: I want to create a STOMP-based REST endpoint. Therefore i created a StompRestController like this:
#Controller
public class StompRestController implements RestController {
#Override
#SubscribeMapping("/users/{user}")
public getUser(#DestinationVariable User user) { // assuming this conversion works
User jsonFriendlyUser = new JacksonAnnotatedUser(user);
return jsonFriendlyUser;
}
I would have expected for #SubscribeMapping/#MessageMapping to follow the same JSON serialization behavior as #RequestMapping. But this is not the case. Instead, when querying this WebSocket/STOMP endpoint, #SubscribeMapping/#MessageMapping-annotated methods will result in sending a STOMP message to clients with a payload/body corresponding to the "normal" Jackson serialization rules, e.g.
{
"id":123,
"name":"Charlie"
"friends":[{argh recursion}, ...],
"unimportantProperty":"This property shall not be part of JSON serialization"
}
Therefore:
How can I have #SubscribeMapping/#MessageMapping-annotated methods obey custom #JsonXXX annotations for returned values?
Is there another way aside #JsonXXXfor doing such returned value serialization?
I am trying to submit a form from Ext JS 4 to a Spring 3 Controller using JSON. I am using Jackson 1.9.8 for the serialization/deserialization using Spring's built-in Jackson JSON support.
I have a status field that is initially null in the Domain object for a new record. When the form is submitted it generates the following json (scaled down to a few fields)
{"id":0,"name":"someName","status":""}
After submitted the following is seen in the server log
"nested exception is org.codehaus.jackson.map.JsonMappingException: Can not construct instance of com.blah.domain.StatusEnum from String value '': value not one of the declared Enum instance names"
So it appears that Jackson is expecting a valid Enum value or no value at all including an empty string. How do I fix this whether it is in Ext JS, Jackson or Spring?
I tried to create my own ObjectMapper such as
public class MyObjectMapper extends Object Mapper {
public MyObjectMapper() {
configure(DeserializationConfig.Feature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT, true);
}
}
and send this as a property to MappingJacksonMappingView but this didn't work. I also tried sending it in to MappingJacksonHttpMessageConverter but that didn't work. Side question: Which one should I be sending in my own ObjectMapper?
Suggestions?
The other thing you could do is create a specialized deserializer (extends org.codehaus.jackson.map.JsonDeserializer) for your particular enum, that has default values for things that don't match. What I've done is to create an abstract deserializer for enums that takes the class it deserializes, and it speeds this process along when I run into the issue.
public abstract class EnumDeserializer<T extends Enum<T>> extends JsonDeserializer<T> {
private Class<T> enumClass;
public EnumDeserializer(final Class<T> iEnumClass) {
super();
enumClass = iEnumClass;
}
#Override
public T deserialize(final JsonParser jp,
final DeserializationContext ctxt) throws IOException, JsonProcessingException {
final String value = jp.getText();
for (final T enumValue : enumClass.getEnumConstants()) {
if (enumValue.name().equals(value)) {
return enumValue;
}
}
return null;
}
}
That's the generic class, basically just takes an enum class, iterates over the values of the enum and checks the next token to match any name. If they do it returns it otherwise return null;
Then If you have an enum MyEnum you'd make a subclass of EnumDeserializer like this:
public class MyEnumDeserializer extends EnumDeserializer<MyEnum> {
public MyEnumDeserializer() {
super(MyEnum.class);
}
}
Then wherever you declare MyEnum:
#JsonDeserialize(using = MyEnumDeserializer.class)
public enum MyEnum {
...
}
I'm not familiar with Spring, but just in case, it may be easier to handle that on the client side:
Ext.define('My.form.Field', {
extend: 'Ext.form.field.Text',
getSubmitValue: function() {
var me = this,
value;
value = me.getRawValue();
if ( value === '' ) {
return ...;
}
}
});
You can also disallow submitting empty fields by setting their allowBlank property to false.
Ended up adding defaults in the EXT JS Model so there is always a value. Was hoping that I didn't have to this but it's not that big of a deal.
I have the same issue. I am reading a JSON stream with some empty strings. I am not in control of the JSON stream, because it is from a foreign service. And I am always getting the same error message. I tried this here:
mapper.getDeserializationConfig().with(DeserializationConfig.Feature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);
But without any effect. Looks like a Bug.