I know how to customize the default ObjectMapper bean. But for one specific Controller/endpoint, I'd like to use a different objectmapper. How can I do this?
I think my question is similar to this one but there are no answers yet. Happy to get an answer there and mark this as duplicate
There's a good solution by #xerx593 linked in the question's comments but I took a different approach for mine because I was returning a generic Map<String,Object> graphql return type and I didn't feel comfortable changing the media-type or applying the object mapper to all Map's. I prefer their solution for the general case as it's more elegant
I simply serialized the return object as a string and returned it.
For example, I turned something like this
#GetMapping(produces = MediaType.APPLICATION_JSON_VALUE)
public Foo getFoo() {
return new Foo();
}
to something like this
private ObjectMapper customMapper = ...;
#GetMapping(produces = MediaType.APPLICATION_JSON_VALUE)
public String getFoo() {
return customMapper.writeValueAsString(new Foo());
}
Related
This seems to be a missing part in the documentation of Vaadin...
I call an API to get data in my UI like this:
#Override
public URI getUri(String url, PageRequest page) {
return UriComponentsBuilder.fromUriString(url)
.queryParam("page", page.getPageNumber())
.queryParam("size", page.getPageSize())
.queryParam("sort", (page.getSort().isSorted() ? page.getSort() : ""))
.build()
.toUri();
}
#Override
public Mono<Page<SomeDto>> getDataByPage(PageRequest pageRequest) {
return webClient.get()
.uri(getUri(URL_API + "/page", pageRequest))
.retrieve()
.bodyToMono(new ParameterizedTypeReference<>() {
});
}
In the Vaadin documentation (https://vaadin.com/docs/v10/flow/binding-data/tutorial-flow-data-provider), I found an example with DataProvider.fromCallbacks but this expects streams and that doesn't feel like the correct approach as I need to block on the requests to get the streams...
DataProvider<SomeDto, Void> lazyProvider = DataProvider.fromCallbacks(
q -> service.getData(PageRequest.of(q.getOffset(), q.getLimit())).block().stream(),
q -> service.getDataCount().block().intValue()
);
When trying this implementation, I get the following error:
org.springframework.core.codec.CodecException: Type definition error: [simple type, class org.springframework.data.domain.Page]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.springframework.data.domain.Page` (no Creators, like default constructor, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
at [Source: (io.netty.buffer.ByteBufInputStream); line: 1, column: 1]
grid.setItems(lazyProvider);
I don't have experience with vaadin, so i'll talk about the deserialization problem.
Jackson needs a Creator when deserializing. That's either:
the default no-arg constructor
another constructor annotated with #JsonCreator
static factory method annotated with #JsonCreator
If we take a look at spring's implementations of Page - PageImpl and GeoPage, they have neither of those. So you have two options:
Write your custom deserializer and register it with the ObjectMapper instance
The deserializer:
public class PageDeserializer<T> extends StdDeserializer<Page<T>> {
public PageDeserializer() {
super(Page.class);
}
#Override
public Page<T> deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JacksonException {
//TODO implement for your case
return null;
}
}
And registration:
SimpleModule module = new SimpleModule();
module.addDeserializer(Page.class, new PageDeserializer<>());
objectMapper.registerModule(module);
Make your own classes extending PageImpl, PageRequest, etc. and annotate their constructors with #JsonCreator and arguments with #JsonProperty.
Your page:
public class MyPage<T> extends PageImpl<T> {
#JsonCreator
public MyPage(#JsonProperty("content_prop_from_json") List<T> content, #JsonProperty("pageable_obj_from_json") MyPageable pageable, #JsonProperty("total_from_json") long total) {
super(content, pageable, total);
}
}
Your pageable:
public class MyPageable extends PageRequest {
#JsonCreator
public MyPageable(#JsonProperty("page_from_json") int page, #JsonProperty("size_from_json") int size, #JsonProperty("sort_object_from_json") Sort sort) {
super(page, size, sort);
}
}
Depending on your needs for Sort object, you might need to create MySort as well, or you can remove it from constructor and supply unsorted sort, for example, to the super constructor. If you are deserializing from input manually you need to provide type parameters like this:
JavaType javaType = TypeFactory.defaultInstance().constructParametricType(MyPage.class, MyModel.class);
Page<MyModel> deserialized = objectMapper.readValue(pageString, javaType);
If the input is from request body, for example, just declaring the generic type in the variable is enough for object mapper to pick it up.
#PostMapping("/deserialize")
public ResponseEntity<String> deserialize(#RequestBody MyPage<MyModel> page) {
return ResponseEntity.ok("OK");
}
Personally i would go for the second option, even though you have to create more classes, it spares the tediousness of extracting properties and creating instances manually when writing deserializers.
There are two parts to this question.
The first one is about asynchronously loading data for a DataProvider in Vaadin. This isn't supported since Vaadin has prioritized the typical case with fetching data straight through JDBC. This means that you end up blocking a thread while the data is loading. Vaadin 23 will add support for doing that blocking on a separate thread instead of keeping the UI thread blocked, but it will still be blocking.
The other half of your problem doesn't seem to be directly related to Vaadin. The exception message says that the Jackson instance used by the REST client isn't configured to support creating instances of org.springframework.data.domain.Page. I don't have direct experience with this part of the problem, so I cannot give any advice on exactly how to fix it.
i need to do something like this
String myVar = "myString";
...
#Preauthorize("customMethod(myVar)")
public void myMethod() {
...
}
but I'm failing at it. How can I do that? It says it cannot be resolved
EDIT:I'm decoupling few rest services and sometimes I have to share infos between them
#Value("${my-properties}")
String urlIWantToShare;
...
#PreAuthorize("isValid(#myValue,urlIWantToShare)")
#RequestMapping(value = "**/letsCheckSecurityConfig", method = RequestMethod.GET)
public boolean letsCheckSecurityConfig(#RequestHeader(name = "MY-VALUE") String myValue)) {
return true;
}
this "isValid" custom security method will call an external service, that doesn't know anything about the caller and his infos. I need to transmit few infos and I need to take them from different kind of sources
One of the sources is my application.properties
EDIT2: I managed to do this
#PreAuthorize("isValid(#myValue, #myProperty)")
#RequestMapping(value = "**/letsCheckSecurityConfig", method = RequestMethod.GET)
public boolean letsCheckSecurityConfig(#RequestHeader(name = "MY-VALUE") String myValue,
#Value("${my-property-from-app-properties}") String myProperty))
..but I want to use not only actual static properties but runtime one. Any help?
You can create a wrapper method without parameters which will call the desired method with parameters. In the annotation you can use the method without parameters
Apologies if I have misunderstood what you are trying to do, but from my understanding you're trying to set an annotation at runtime based on a variable / app.properties, so that you can then read this variable and then execute your class?
If this is the case, You cannot do this from an annotation alone as annotations cannot read local variables and cannot be set at runtime.
However, one option for you is to have an object which contains the 'values' of interest for you and then read the values from the object.
Something like the below:
PoJo
public class testObject{
#test
private String myVar;
private String myValue;
//Getters and Setters
}
Get Object values
public void getFields (Object obj){
Field fields = obj.getClass().getDeclaredFields();
for (Field f : fields){
test fieldAnnotation = f.getAnnotation(test.Class);
if (fieldAnnotation != null){
f.get(obj);
// Do checks based on this
}
}
}
Main Class
public static void main(String[] args){
//Create object
testObject test = new testObject();
test.setOne("testOne");
test.setTwo("testTwo");
getFields(test);
}
I've pulled this code based on what I had to do to get the fields - but in my case, I did not know the object types I was going to be passed. You are simply using the annotation to 'mark' the fields you want to retrieve and then reading the value from the object.
If you're in a similar situation, then you can see my answer here: initial answer
Let me know if i've misunderstood this and I can try and further clarify my answer.
I've seen examples on SO of excluding fields from serialization at runtime. I need to do that, but I'd like to have Gson handle serialization of all the fields not being excluded.
The complicating part is that I can't have Gson do the serialization first, then have a TypeAdapter modify the result. I need to somehow do the exclusion first, then have what remains be serialized. Is this even possible?
Ok, with some experimentation, and this helpful post, I was able to cobble together a way to conditionally exclude mocked fields.
The reason I'm going to all this trouble is that out-of-the-box Gson throws an exception when it encounters Spock-mocked fields.
For Spock, my check to determine if a field is mocked is to see if the class name of the value it references contains the substring EnhancerByCGLib.
Below, ResizingArrayQueueOfStrings.arrayFactory is the field that may, or may not, be mocked.
Thankfully, I can use a single JsonSerializer for all classes that need this sort of treatment. Ideally, I wouldn't have to register the serializer for every class that might be mocked... but that's a battle for another day.
The resulting JSON, when the field is mocked and ResizingArrayQueueOfStrings is serialized, is
queue {
"arrayFactory": "** mocked **",
}
otherwise, it's
queue {
"arrayFactory": {},
}
Hope this helps others with a similar need.
public class MockSerializer implements JsonSerializer<Object> {
#Override
public JsonElement serialize(Object src, Type typeOfSrc, JsonSerializationContext context) {
Gson gson = new Gson();
String className = src.getClass().getName();
boolean isMocked = className.contains("EnhancerByCGLIB");
if (isMocked) return new JsonPrimitive("** mocked **");
else return gson.toJsonTree(src);
}
}
public class ResizingArrayQueueOfStrings {
private ArrayFactory arrayFactory;
public String toString() {
Gson gson = new GsonBuilder()
.registerTypeAdapter(ArrayFactory.class, new MockSerializer())
.setPrettyPrinting()
.create();
return gson.toJson(this);
}
}
sorry for general question, but I can't google anything on that, we use spring mvc 2.5 in our project, so there is no #ResponseBody annotation, how can I make something like this without it?
You could just return it as a string built with the Jackson object mapper:
public String getCustomDetails(#PathVariable String variable1) {
CustomDetails details = new CustomDetails(variable1);
ObjectMapper mapper = new ObjectMapper();
String result = null;
result = mapper.writeValueAsString(details);
return result;
}
That should work. Might have to surround the call to writeValueAsString in a try-catch.
Edit: I should clarify that "CustomDetails" and "variable1" are just example values... they could be anything.
Is there a better way to pass multiple JSON objects and capture it in #RequestBody in Spring 3? I had referred this, but do not wish to define new wrapper classes for the purpose as explained in that question? Is it Spring's limitation or REST limitation (based on my understanding, this should not be the case)? Desperately need answer, and since I could not post additional comments in same question (was deleted), hence posting it here.
Thanks,
Paddy
for each model use #JsonIgnoreProperties(ignoreUnknown = true)
#RequestMapping(value = "/users/testBean", method = RequestMethod.POST, consumes={"application/json","application/xml"}, produces={"application/json","application/xml"})
public #ResponseBody List<User> testBean(#RequestBody Object object) {
System.out.println("testBean called");
System.out.println(object.toString());
ObjectMapper mapper=new ObjectMapper();
User user =mapper.convertValue(object, User.class);
Tree tree =mapper.convertValue(object, Tree.class);
System.out.println("User:"+user.toString());
System.out.println("Tree:"+tree.toString());
return userService.findAll();
}