I have two controllers in my Application; one is userController, where I have add, delete and update methods; the other one is studentController, where I also have add, delete and update methods.
All the mappings are same in my methods using #RequestMapping annotation in both controllers. I have one confusion: if we are passing the same action from the JSP, then how will the Dispatcher find the corresponding controller? If anybody could describe this using example will be appreciated.
You have to set a #RequestMapping annotation at the class level the value of that annotation will be the prefix of all requests coming to that controller,
for example:
you can have a user controller
#Controller
#RequestMapping("user")
public class UserController {
#RequestMapping("edit")
public ModelAndView edit(#RequestParam(value = "id", required = false) Long id, Map<String, Object> model) {
...
}
}
and a student controller
#Controller
#RequestMapping("student")
public class StudentController {
#RequestMapping("edit")
public ModelAndView edit(#RequestParam(value = "id", required = false) Long id, Map<String, Object> model) {
...
}
}
Both controller have the same method, with same request mapping but you can access them via following uris:
yourserver/user/edit
yourserver/student/edit
hth
We can have any number of controllers, the URL mapping will decide which controller to call..
Please refer here for detailed Spring MVC multiple Controller example
Related
I am writing an API using Spring Boot, and I have a abstract controller to hold the shared logic among several controllers. Now I want to add a warning field:
public abstract class BaseController<T> {
public List<String> warnings;
#RequestMapping(method = POST)
public Response create(HttpServletRequest request,HttpServletResponse response) {
warnings = new ArrayList<>();
if (something bad from T) {
warning.add("bad thing happens");
}
return createRespone(warnings);
}
(createReponse is uesd to create custom reponse)
And I have several different controller inherited from it
#RestController
#RequestMapping("/{area}/blah")
public class BlahController extends BaseController<Blah> {
}
For the warning field, will it be shared several different children controller, or will only one instance alive? If controller A and controller B are both inherited from BaseController and tried to modify warning, is it thread safe?
The warning field is not shared. Your code is equivalent to:
BaseController<blah> blahController = new BlahController();
BaseController<noh> nohController = new NohController();
Having state in a controller is against the REST concepts.
I have a bunch of params in my controller and want to map all of them to a separate POJO to keep readability. There is also a #CookieValue, #RequestHeader I need to evaluate and aim for a solution to also map them to that POJO. But how?
I saw a possible solution on a blog but it doesn't work, the variable stays null.
Controller:
#RequestMapping(path = MAPPING_LANGUAGE + "/category", produces = MediaType.TEXT_HTML_VALUE)
#ResponseBody
public String category(CategoryViewResolveModel model) {
doSomething();
}
And my POJO is this:
public class CategoryViewResolveModel {
private String pageLayoutCookieValue;
public CategoryViewResolveModel() {
}
public CategoryViewResolveModel(
#CookieValue(value = "SOME_COOKIE", required = false) String pageLayoutCookieValue) {
this.pageLayoutCookieValue = pageLayoutCookieValue;
}
... some other RequestParams, PathVariables etc.
}
According to the documentation it's not possible for #CookieValue and #RequestHeader.
This annotation is supported for annotated handler methods in Servlet
and Portlet environments.
Take a look at:
https://www.petrikainulainen.net/programming/spring-framework/spring-from-the-trenches-creating-a-custom-handlermethodargumentresolver/
instead of using getParameter to access request parameters you can use getHeader to retrieve the header value and so define your CategoryViewResolveModel just as you were requesting
Is there a way to add an attribute to all paths of a certain user?
I.e I am trying to reach the current logged in administrator on all pages the administrator can reach, but I don't want to add this attribute to every single controller.
Something like this, where I don't need to return anything:
#RequestMapping(value = {"admin/**"}, method = RequestMethod.GET)
public void adminPaths(ModelMap model) {
model.addAttribute("user", getPrincipal());
}
You can use #ModelAttributes on a method in a controller. An #ModelAttribute on a method indicates the purpose of that method is to add one or more model attributes to all controller methods:
#Controller
#RequestMapping("/admin")
public class AdminController {
...
#ModelAttribute
public void populateModel(Model model) {
model.addAttribute("user", getPrincipal());
// add more ...
}
...
}
#ModelAttribute methods in a controller are invoked before #RequestMapping methods, within the same controller.
For truly wildcard matching, you can use ControllerAdvice and ModelAttributes on methods together. Something like following:
#ControllerAdvice(annotations = Controller.class)
public class AdminPopulatorAdvice {
#ModelAttribute
public void populateModel(HttpServletRequest request, Model model) {
// examine the request
// if its path contains /admin, then add attribute
model.addAttribute("user", getPrincipal());
// add more ...
}
}
I forgot to mention that I was using Spring security.
Bohuslav pointed me into the right direction and ended up here: https://docs.spring.io/spring-security/site/docs/current/reference/html/taglibs.html
I am building a web application in Spring MVC with combination of Spring Security. My question regards to inner design of application. To be more specific - how to set up controllers. I got inspired a lot by Pet Clinic example where there is one controller per domain object (Owner controller, Pet controller, Vet Controller and so on).
I would like to introduce an admin backend interface to my application. This would mean to create admin - specific methods and #RequestMappings in each controller. Request mapping paths are secured by intercept-url pattern so I do not have to care where they are. However I find this solution little bit inelegant.
On pet clinics example would it look like:
#Controller
#SessionAttributes(types = Owner.class)
public class OwnerController {
private final ClinicService clinicService;
// Front end method
#RequestMapping(value = "/owners/find", method = RequestMethod.GET)
public String initFindForm(Map<String, Object> model) {
model.put("owner", new Owner());
return "owners/findOwners";
}
// Admin method
#RequestMapping(value = "/admin/owners/find", method = RequestMethod.GET)
public String initFindForm(Map<String, Object> model) {
model.put("owner", new Owner());
//Admin view
return "admin/owners/findOwners";
}
}
Other choice is to have one controller for each #RequestMapping (or per action)
#Controller
#RequestMapping(value = "/admin", method = RequestMethod.GET)
public class AdminController {
private final ClinicService clinicService;
// Admin method
#RequestMapping(value = "/owners/find", method = RequestMethod.GET)
public String initFindForm(Map<String, Object> model) {
model.put("owner", new Owner());
//Admin specific view
return "admin/owners/findOwners";
}
}
This would in my opinion lead to really robust controllers with many methods.
Third option would be to have some kind of mix of those.
#Controller
#SessionAttributes(types = Owner.class)
public class AdminOwnerController {
private final ClinicService clinicService;
// Admin method
#RequestMapping(value = "/admin/owners/find", method = RequestMethod.GET)
public String initFindForm(Map<String, Object> model) {
model.put("owner", new Owner());
//Admin view
return "admin/owners/findOwners";
}
}
My question is what is a standard approach for that?
Usually I use a hybrid approach of AdminOwnerController, in which I end up having approximately 5-10 methods max per Controller.
If you end up having 1-2 methods per controller. I would consider grouping them together based on the admin domain.
I have a Spring MVC web application with conroller like below :
#Controller
public class ActionRestController {
#RequestMapping(value = "/list", method = GET)
#ResponseBody
public List<Action> list(Action action, SearhCriteria searchCriteria) {
List<Action> ret = new ArrayList<Action>();
// Call a service method to get the records
// Copy the records into the list
// return the list of objects
return ret;
}
The Controller is invoked when the user does a search. There are several such controllers in the app, one for each searchable entity.
For reasons that I cannot explain very well, here, I cannot modify these controllers in anyway.
But now, I have requirement in the UI to display the search criteria and the no. of records and paging details, as well. This information is not returned by the controller. The JSON returned by the Controller contains just the list of records.
I have put up a different controller which will handle the request, gets and puts the extra info in the model and forwards the request to the existing controller like below :
#Controller
public class ActionExtendedController {
#RequestMapping(value = "/searchlist", method = GET)
#ResponseBody
public List<Action> list(Action action, SearhCriteria searchCriteria, Model model) {
model.addAttribute("searchParameters", searchCriteria);
return "forward:/list";
}
Upto this point, all is well.
What I want to do is intercept the request at a point where the List is returned from the controller, before it is converted to JSON, and return a map containing the list and the search parameters.
Now since the 'immutable' controller users ResponseBody the control goes to the JacksonMessageConverter amd the response goes out from there. I have already tried the following paths and they do not work.
Interceptor - By the time I get here, the response is already written out, so there is no way to change it.
Custom ObjectMapper for the JasksonMessageConverter - Will not work, since I do not have access to the model object inside the mapper, I only have access to the list returned by the controller.
Aspect #After pointcut for the controller - I think this technique will work, but I cannot get it to work. The advise does not fire and I am sure I am missing something in the configuration.
Is there a way to get Spring AOP to fire on a annotated controller, handler method or
can anyone suggest another method of intercepting the handler return value (along with the model) ?
How about a simple delegation to the base controller in your extended controller:
#Controller
public class ActionExtendedController {
#Autowired ActionRestController baseRestController;
#Autowired MappingJacksonJsonView mappingJacksonJsonView;
#RequestMapping(value = "/searchlist", method = GET)
public View list(Action action, SearhCriteria searchCriteria, Model model) {
List<Action> actions = baseRestController.list(action, searchCriteria, model);
model.addAttribute("actions", actions);
model.addAttribute("searchParameters", searchCriteria);
return mappingJacksonJsonView;
}
this way you are delegating to the original controller, but using this new controller for the view. Just register a mappingJacksonJsonView as a bean also which will serialize all model objects (searchcriteria and actions) into the json view. You need not even return a view but can also use #ResponseBody, with a type that can hold the responses and search criteria.
Why don't you change the return type to a Map? Like:
#Controller
public class ActionRestController {
#RequestMapping(value = "/list", method = GET)
#ResponseBody
public Map<String, Object> list(Action action, SearhCriteria searchCriteria) {
Map<String, Object> map = new HashMap<String, Object>();
List<Action> ret = new ArrayList<Action>();
// Call a service method to get the records
// Copy the records into the list
// return the list of objects
map.put("searchResult",ret);
map.put("searchCriteria", searchCriteria);
return map;
}