Implementation of the WebSocketMessageBrokerConfigurer must implement two methods. configureMessageBroker is one of them:
public void configureMessageBroker(MessageBrokerRegistry registry) {
registry.setApplicationDestinationPrefixes("/app")...};
In this example we configured that all messages with "/app" prefix will be routed to #MessageMapping-annotated methods in controller class.
But setApplicationDestinationPrefixes accepts array of the Strings of variable length.
How to assign this or that particular method in a controller all of them annotated with #MessageMapping to a specific prefix in case we have several prefixes?
Initially I thought that the answer was to use #MessageMapping not only over the methods but over the controller class as well and have controller-level annotation mapped to the prefixes while method-level annotation - mapped to the lower parts of the route.
I found an example at https://docs.spring.io/spring-framework/docs/4.3.x/spring-framework-reference/html/websocket.html which gave me this idea:
#Controller
#MessageMapping("foo")
public class FooController {
#MessageMapping("bar.{baz}")
public void handleBaz(#DestinationVariable String baz) {
}
}
but then I noticed that such combination addresses the route "/app/foo.bar.{baz}". {baz} is a placeholder here
Related
I have a not-a-common requirement where I am two different type of consumers for my microservices. One type of consumer is okay with the type-of-response that I am sending them, whereas the other consumer has a requirement where we have to follow their structure (its pretty strict on this).
Lets say I have a StudentController
#RestController
#RequestMapping("/student")
public class StudentController {
#GetMapping("/{name}")
public Student getStudent(#PathVariable String name) {
return Student.builder()
.name(name)
.subjects(List.of("Maths", "English"))
.dateJoined(LocalDate.now().toString())
.build();
}
}
This is alright as one my consumer is accepting my response, where my response looks like this:
{"name":"smit","subjects":["Maths","English"],"dateJoined":"2020-04-26"}
However, the another consumer says that you should sending me the SAME object in a another from something like below:
#RestController
#RequestMapping("/wrapper")
public class WrapperController {
#Autowired
private StudentController studentController;
#GetMapping("/{name}")
public WrapperResponse getStudent(#PathVariable String name){
return WrapperResponse.builder()
.responseTimeStamp(LocalDateTime.now().toString())
.data(studentController.getStudent(name))
.build();
}
}
The below is the output of the above controller.
{"data":{"name":"smit","subjects":["Maths","English"],"dateJoined":"2020-04-26"},"responseTimeStamp":"2020-04-26T01:11:32.986"}
Summary: WrapperController is internally calling StudentController and then wrapping the response in the custom "WrapperResponse" class and then sending that as a response.
Problem: As of now it does solve the problem but I have many such controllers and in my different microservices. So I do not want to rewrite the "WrapperController" for each controller and each microservice.
This is very much opinion-based, but here's how I would refactor this:
Create a Student service (StudentService) that creates the Student,
rather than doing that in the Controller.
Push the code for building a WrapperResponse into the WrapperResponse class itself - either as a static 'factory' method, or as constructor. Have the method take a Student as a parameter.
For each different kind of 'Wrapper' object that you want to supply, have your controller method call the StudentService to get the base Student class, and then construct the Wrapper object by passing the Student to the factory method or constructor of the Wrapper object.
So, your WrapperController might end up looking like this:
#RestController
#RequestMapping("/wrapper")
public class WrapperController {
#Autowired
private StudentService studentService;
#GetMapping("/{name}")
public WrapperResponse getStudent(#PathVariable String name){
return new WrapperResponse(studentService.getStudent(name));
}
}
I'm having some trouble implementing a function over some pre-existing code.
Other programmers working on this project previously defined a genric abstract "restcontroller" (it's not actually annotated as #RestController but it's meant to be extended by classes with that annotation)
public abstract class AbstractController<T extends AbstractEntity, R extends JpaRepository<T, Integer>> {
#GetMapping(value = "/getall")
public Paging<T> getAll(#RequestParam Integer itemsPerPage,
#RequestParam Integer pageIndex,
#RequestParam Map<String, String> filters,
#Autowired Consumer consumer) {
//Fetch entities of type T from repository R and return them
}
//other generic crud operations
}
This class is usually extended by concrete controllers that simply define other operations on their specific types, but do no alter generic crud operations.
What I want to do is extend this class, but override the getAll method, like this:
#RestController
#RequestMapping("/api/tasks")
public class TaskController extends AbstractController<Task, TaskRepository> {
#Override
public Paging<Task> getAll(Integer itemsPerPage, Integer pageIndex, Map<String, String> filters, Consumer consumer) {
LoggerFactory.getLogger(LazyTaskController.class).log("function called successfully!");
Paging<Task> paging = super.getAll(itemsPerPage, pageIndex, filters, consumer);
//do things with return value before returning
return paging;
}
}
If I call BASEURL/api/tasks/getall?itemsPerPage=25&pageIndex=0 without overriding the getAll method, the parameters are wired correctly (the Map contains two values, itemsPerPage and pageIndex, as expected, and consumer contains a concrete implementation of the intercace Consumer).
However if I do override it, the Map for some reason contains two values, one with key "consumer" and type Proxy, and another with key "org.springframework.validation.BindingResult.consumer" and value of type BeanPropertyBindingResult; and consumer contains a Proxy.
I suppose the #Override interferes with the autowiring of Consumer, but I can't figure out how to properly achieve what I have in mind (manipulating the results of getAll before returning them).
Thank you in advance
Nevermind, I solved it.
The problem with the Map was solved by adding #RequestParam and #Autowired annotations to the overridden method parameters as well.
The problem with the Consumer concrete type was somehow solved by applying a custom annotation that I found on another class in the codebase, I'm still not sure about what that annotation does but at least I know what to look for now.
I am having two implementations of my component.
public interface MyComponent {
}
imple1
#Component("impCompf")
#Lazy
#RequestScope
public class ImpComp1 implements MyComponent {
}
imple2
#Component("impComps")
#Lazy
#RequestScope
public class ImpComp2 implements MyComponent {
}
What I did so far is to create two conditions like so:
imple1
public class FirstCondition implements Condition {
#Override
public boolean matches(ConditionContext arg0, AnnotatedTypeMetadata arg1) {
return staticVariable.contains("impCompf");
}
}
Same goes for imple2
and define a configuration class
#Configuration
public class MyConfiguration {
#Bean
#Conditional(FirstCondition .class)
#Primary
public MyComponent getComp1() {
return new ImpComp1();
}
public static String staticVariable= "impCompf";
and in My main controller:
#RequestMapping(value="api/{co}", method=RequestMethod.POST)
public ResponseEntity<Modelx> postSe(#PathVariable("co") String co) {
if(co.contains("impCompf"))
staticVariable = "impCompf";
else (co.contains("impComps"))
staticVariable = "impComps";
What I want: for every http request I want to load proper implementation
But however what I am getting is the implementation defined first in the static variable.
If is there another elegant and better way, i'd like to know about it.
I think there is some confusion here about the purpose of the conditions. These aren't being used at the time your requests arrive to autowire the candidate bean into your controller. These are being used when the application is started to configure the application context based on the environment and classpath etc...
There is no need for the conditional classes that you have created. This is defining the configuration of the beans when the context starts and not on a per request basis at runtime.
The use of the static variable is also problematic is a scenario with one or more concurrent requests or in a case where multiple threads may observe different values unless some other mechanism in the java memory model is being used (such as volatile or establishing a happens before relationship, e.g. with sychnronized)
There are a number of ways to do what you appear to be trying to achieve. Since ultimately, you appear to be using a path parameter supplied by a client to determine which service you want to invoke you could use a classic factory pattern to return the correct interface implementation based on the string input programmatically.
Alternatively you could create two distinct controller methods which are distinguished by a query parameter or endpoint name or path match etc. You could then have the appropriate service injected by a qualified bean name
Although perhaps generally recommended, you could also inject an application context instance and search the it looking for the relevant bean by name or class: https://brunozambiazi.wordpress.com/2016/01/16/getting-spring-beans-programmatically/ - although This is more cumbersome and you'd need to handle things like org.springframework.beans.factory.NoSuchBeanDefinitionException or casting in some cases - best avoided in favour of one of the other methods.
In our REST-API we need to be multi-tenant capable. For achiving this all rest controllers subclass a common REST controller which defines a request mapping prefix and exposes a model attribute as follows
#RequestMapping(path = "/{tenantKey}/api")
public class ApiController {
#ModelAttribute
public Tenant getTenant(#PathVariable("tenantKey") String tenantKey) {
return repository.findByTenantKey(tenantKey);
}
}
Derived controllers make use of the model attributes in their request mapping methods:
#RestController
public class FooController extends ApiController {
#RequestMapping(value = "/foo", method = GET)
public List<Foo> getFoo(#ApiIgnore #ModelAttribute Tenant tenant) {
return service.getFoos(tenant);
}
}
This endpoint gets well documented in the swagger-ui. I get an endpoint documented with a GET mapping for path /{tenantKey}/api/foo.
My issue is, that the {tenantKey} path variable is not documented in swagger-ui as parameter. The parameters section in swagger is not rendered at all. If I add a String parameter to controller method, annotating it with #PathVariable("tenantKey) everything is fine, but I don't want a tenantKey parameter in my controller method, since the resolved tenant is already available as model attribute.
So my question is: Is there a way do get the #PathVariable from the #ModelAttriute annotated method in ApiController documented within swagger-ui in this setup?
Project-Setup is
Spring-Boot (1.4.2)
springfox-swagger2 (2.6.1)
springfox-swagger-ui (2.6.1)
This is certainly possible. Model attributes on methods are not supported currently. Instead, you could take the following approach.
Mark the getTenant method with an #ApiIgnore (not sure if it gets treated as a request mapping.)
In your docket you can add tenantKey global path variable (to all end points). Since this is a multi-tenant app it's assuming this applies to all endpoints.
Please find my HomeController and DemoController
class HomeController{
#RequestMapping(value="index")
public void home(){
}
}
class DemoController{
#RequestMapping(value="index")
public void demo(){
}
}
when I try to send a request to index, which one will get executed?
I wanted to know how can we have same request mapping value for multiple controllers
https://stackoverflow.com/a/34590355/2682499 is only partially correct at this point.
You can have multiple controller methods use the same URI so long as you provide Spring enough additional information on which one it should use. Whether or not you should do this is a different question. I would certainly not recommend using the same URI in two separate controller classes to avoid confusion, though.
You can do something like this:
class HomeController{
#RequestMapping(value="/index", params = {"!name", "!foo"})
public List<Something> listItems(){
// retrieve Something list
}
#RequestMapping(value="/index", params = "name")
public List<Something> listItems(String name) {
// retrieve Something list WHERE name LIKE %name%
}
#RequestMapping(value="/index", params = {"!name", "foo"})
public List<Something> listItems(String foo) {
// Do something completely different
}
}
For the full documentation on what is possible when overloading URIs you should reference the #ReqeustMapping documentation: https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestMapping.html. And, specifically https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestMapping.html#params-- for the section request parameters.
In Spring Web MVC this is not possible. Each mapping must be unique in your context. If not, you will receive a RuntimeException during context initialization.
You cannot even use parameters to differentiate your endpoints because they are not evaluated while searching for a suitable handler (applicable for Servlet environments). From #RequestMapping javadoc:
In a Servlet environment, parameter mappings are considered as restrictions that are enforced at the type level. The primary path mapping (i.e. the specified URI value) still has to uniquely identify the target handler, with parameter mappings simply expressing preconditions for invoking the handler.
Note that you can do the opposite, so multiple URLs can point to the same handler. Have a look at Spring MVC: Mapping Multiple URLs to Same Controller
Unfortunately, this is not possible. The request mapping has to be unique otherwise the application can't determine which method the incoming request should be mapped to.
What you can do instead is to extend the request mapping:
class HomeController{
#RequestMapping(value="home/index")
public void home(){
}
}
class DemoController{
#RequestMapping(value="demo/index")
public void demo(){
}
}