I'd like to know if there is a way I can forward a request from one controller to another without actually changing the URL in the browser.
#RequestMapping(value= {"/myurl"})
public ModelAndView handleMyURL(){
if(somecondition == true)
//forward to another controller but keep the url in the browser as /myurl
}
examples that I found online were redirecting to another url which was causing other controllers to handle that. I don't want to change the URL.
Try to return a String instead of ModelAndView, and the String being the forward url.
#RequestMapping({"/myurl"})
public String handleMyURL(Model model) {
if(somecondition == true)
return "forward:/forwardURL";
}
Instead of forwarding, you may just call the controller method directly after getting a reference to it via autowiring. Controllers are normal spring beans:
#Controller
public class MainController {
#Autowired OtherController otherController;
#RequestMapping("/myurl")
public String handleMyURL(Model model) {
otherController.doStuff();
return ...;
}
}
#Controller
public class OtherController {
#RequestMapping("/doStuff")
public String doStuff(Model model) {
...
}
}
As far as I know "forward" of a request will be done internally by the servlet, so there will not be a second request and hence the URL should remain the same. Try using the following code.
#RequestMapping(value= {"/myurl"})
public ModelAndView handleMyURL(){
if(somecondition == true){
return new ModelAndView("forward:/targetURL");
}
}
Related
How can I map custom/dunamic requests toa given controller, based on a repository lookup?
The use-case is a CMS-like feature in a web-platform, where certain URL patterns ("pages") stored in the DB should be handled by a separate controller PageController.java. These patterns are not necessarily known at compile-time, and they can also be added and modified while the app is deployed (thus, it cannot be annotation-driven).
I did try to map a controller to "**" (see below), but that did not work for 2 reasons: firstly all other requests resolved to that same controller method (I had hoped that it would use "**" as a fallback and try the others first), and it also ended up resolving all requests to my static/asset files to this controller (resulting in unwanted 404-responses).
#Controller
public class PageController {
#Inject
private PageService pageService;
#RequestMapping(value = "**", method = RequestMethod.GET)
public String getPage(Model model, HttpServletRequest request, #CurrentUser User user) {
String path = request.getRequestURI();
Page page = this.pageService.getByPath(path, user);
if (page == null) {
throw new NotFoundException();
}
model.addAttribute("page", page);
return "web/page";
}
}
The temporary work-around/modification to the above method has so far been to map a pre-defined URL-prefixes to this controller (eg. /page/**, /info/**, /news/** etc), but this is an inelegant solution that adds arbitrary limitations to the system which I now seek to eliminate.
I am currently using Spring Boot 2.0. In addition to the naive mapping to ** in a regular #Controller class (using the #RequestMapping -annotation), I have also tried configuring SimpleUrlHandlerMapping the following way:
#Configuration
public class WebConfig implements WebMvcConfigurer {
#Inject
private PageDao pageDao;
#Bean
public PageController pageController() {
return new PageController();
}
#Bean
public SimpleUrlHandlerMapping pageUrlHandlerMapping() {
SimpleUrlHandlerMapping pageUrlHandlerMapping = new SimpleUrlHandlerMapping();
PageController pageController = this.pageController();
Map<String, Object> urlMap = this.pageDao.findAll().stream()
.map(Page::getNormalizedSlug)
.collect(Collectors.toMap(Function.identity(),
slug -> pageController, (existing, duplicate) -> existing));
pageUrlHandlerMapping.setUrlMap(urlMap);
pageUrlHandlerMapping.setOrder(Ordered.HIGHEST_PRECEDENCE); // <- Cannot be LOWEST_PRECEDENCE for some reason...
return pageUrlHandlerMapping;
}
}
public class PageController implements Controller {
#Inject
private PageService pageService;
#Inject
private DmaWebControllerAdvice controllerAdvice;
#Override
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
User user = null;
Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();
if (principal instanceof User) {
user = (User) principal;
}
String path = request.getRequestURI();
Page page = this.pageService.getByPath(path, user);
if (page == null) {
throw new NotFoundException();
}
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName("web/page");
modelAndView.addObject("page", page);
controllerAdvice.globalModelAttributes(modelAndView.getModel(), null);
return modelAndView;
}
}
This approach does technically work, but the list of pages will somehow have to be reloaded into the SimpleUrlHandlerMapping whenever one of the pages is changed (i am not quite sure how to do that). This also possibly overwrites some default Spring Boot-configuration, that I would ideally like to keep. It also has some drawbacks compared to resolving controllers using #Controller and #RequesMapping because I currently am injecting certain data into all views resolved that way (mainly model-data used in the overall design of the website, like menu, quicklinks etc). In the above attempt, I have had to set those via a separate call to controllerAdvice-globalModelAttributes().
What I am seeking is a solution where my repository is queried for potential page-matches in runtime, and if it is valid then the request will be handled by the proper page-controller. Is a custom HandlerMapping -implementation the way to do this? And if not, how should I solve this? And if making a separate HandlerMapping for pages, how do I add/register this in my configuration without overwriting the default provided by Spring?
Why don't you just implement a catch-all controller which parses your patterns as a parameter, does a db look-up and then use a forward to specific controllers (info, page, news etc.)? Seems like for a CMS, this look-up logic belongs into your code (e.g. service layer).
Easiest(but not the best) way to achieve what you need is creating custom HandlerMapping implementation:
public class PageMapper implements HandlerMapping, Ordered {
private HandlerMethod handlerMethod;
public CustomMapper(Object controller, Method method) {
this.handlerMethod = new HandlerMethod(controller, method);
}
#Override
public HandlerExecutionChain getHandler(HttpServletRequest httpServletRequest) throws Exception {
return new HandlerExecutionChain(handlerMethod);
}
#Override
public int getOrder() {
return Ordered.LOWEST_PRECEDENCE; //you have to add the handler to the end
}
}
Now remove #Controller annotation from PageController because you don't need it to be detected automatically anymore. After that register controller and mapping to config:
#Configuration
public class AppWebConfig implements WebMvcConfigurer {
#Bean
public PageController pageController() {
return new PageController();
}
#Bean
public HandlerMapping pageMapping(PageController pageController) {
Method method = BeanUtils.resolveSignature("getPage", PageController.class);
return new PageMapping(pageController, method);
}
}
Now every request unrecognized by other HandlerMapping instances will be sent to your mapping hence to your controller. But this approach has obvious disadvantage. Since your mapping is the last in the chain of mappings you never get 404 error. Therefor you never know about something wrong with you resources (e.g. if some of them are missing).
I would prefer let application to distinguish paths by prefix (just like you do it already), where prefix is operation application is going to do with a page. For example if you need to show or edit the page:
#Controller
public class PageController {
private final static String SHOW = "/show";
private final static String EDIT = "/edit";
#Inject
private PageService pageService;
GetMapping(value = SHOW + "/**")
public String getPage(Model model, HttpServletRequest request, #CurrentUser User user) {
String path = request.getRequestURI().substring(SHOW.length());
Page page = this.pageService.getByPath(path, user);
...
model.addAttribute("page", page);
return "web/page";
}
//the same for EDIT operation
}
I am pretty new in Spring MVC and I have the following doubt.
In a controller, I have a method annotated in this way:
#Controller
#RequestMapping(value = "/users")
public class UserController {
#RequestMapping(params = "register")
public String createForm(Model model) {
model.addAttribute("user", new Customer());
return "user/register";
}
}
So this method handle HTTP Request toward the URL /users?register where register is a parameter (because the entire class handle request toward /users resource).
Is it the same thing if, instead using the params = "register" I use the following syntaxt:
#Controller
public class UserController {
#RequestMapping("/users/{register}")
public String createForm(Model model) {
model.addAttribute("user", new Customer());
return "user/register";
}
}
I have deleted the mapping at class level and I use #RequestMapping("/users/{register}").
Is it the same meaning of the first example?
NO, they are completely different constructs:
Code 1
#Controller
#RequestMapping(value = "/users")
public class UserController {
#RequestMapping(params = "register")
public String createForm(Model model) {
model.addAttribute("user", new Customer());
return "user/register";
}
}
In this case, createForm method will be called when a HTTP request is made at URL /users?register. Quoting from Spring Javadoc, it means this method will be called whatever the value of the register HTTP parameter; it just has to be present.
"myParam" style expressions are also supported, with such parameters having to be present in the request (allowed to have any value).
Code 2
#Controller
public class UserController {
#RequestMapping("/users/{register}")
public String createForm(Model model) {
model.addAttribute("user", new Customer());
return "user/register";
}
}
In this case, #RequestMapping is declaring register as a PathVariable. The method createForm will be called if a HTTP request is made at URL /users/something, whatever the something. And you can actually retrieve this something like this:
#RequestMapping("/users/{register}")
public String createForm(#PathVariable("register") String register, Model model) {
// here "register" will have value "something".
model.addAttribute("user", new Customer());
return "user/register";
}
I have a controller which handles a specific URL
#RequestMapping(value= {"/myurl"})
public ModelAndView handleMyURL()
Instead I want to have 2 separate controllers that let me handle this same /myurl based on the parameters passed to it.
If URL is
/myurl?a=1
goto controller A, otherwise use controller B.
Is there a way to do that?
I found this similar question Spring MVC - Request mapping, two urls with two different parameters
where someone has mentioned "use one method in a misc controller that dispatches to the different controllers (which are injected) depending on the request param." , how do I implement that?
Controller 1
#RequestMapping(value= {"/myurl"}, params = { "a" })
public ModelAndView handleMyURL()
Controller 2
#RequestMapping(value= {"/myurl"}, params = { "b" })
public ModelAndView handleMyURL()
Take a look at chapter 4 of this post for more detail
#Controller
#RequestMapping(value= {"/myurl"})
public TestController{
#Autoware
private TestAController testAController;
#Autoware
private TestBController testBController;
public void myMethod(String a){
if(a.equals("1"){
testAController.foo(a);
}else{
testBController.foo(a);
}
}
}
#Controller
#RequestMapping(value= {"/myurl1"})
public class TestAController{
public void foo(String a){
...
}
}
#Controller
#RequestMapping(value= {"/myurl2"})
public class TestBController{
public void foo(String a){
...
}
}
In Spring MVC, it is easy to bind request parameter to method paramaters handling the request. I just use #RequestParameter("name"). But can I do the same with request attribute? Currently, when I want to access request attribute, I have to do following:
MyClass obj = (MyClass) request.getAttribute("attr_name");
But I really would like to use something like this instead:
#RequestAttribute("attr_name") MyClass obj
Unfortunately, it doesn't work this way. Can I somehow extend Spring functionality and add my own "binders"?
EDIT (what I'm trying to achieve): I store currently logged user inside request attribute. So whenever I want to access currently logged user (which is pretty much inside every method), I have to write this extra line user = (User) request.getAttribute("user");. I would like to make it as short as possible, preferably inject it as a method parameter. Or if you know another way how to pass something across interceptors and controllers, I would be happy to hear it.
Well, I finally understood a little bit how models work and what is #ModelAttribute for. Here is my solution.
#Controller
class MyController
{
#ModelAttribute("user")
public User getUser(HttpServletRequest request)
{
return (User) request.getAttribute("user");
}
#RequestMapping(value = "someurl", method = RequestMethod.GET)
public String HandleSomeUrl(#ModelAttribute("user") User user)
{
// ... do some stuff
}
}
The getUser() method marked with #ModelAttribute annotation will automatically populate all User user parameters marked with #ModelAttribute. So when the HandleSomeUrl method is called, the call looks something like MyController.HandleSomeUrl(MyController.getUser(request)). At least this is how I imagine it. Cool thing is that user is also accessible from the JSP view without any further effort.
This solves exactly my problem however I do have further questions. Is there a common place where I can put those #ModelAttribute methods so they were common for all my controllers? Can I somehow add model attribute from the inside of the preHandle() method of an Interceptor?
Use (as of Spring 4.3) #RequestAttribute:
#RequestMapping(value = "someurl", method = RequestMethod.GET)
public String handleSomeUrl(#RequestAttribute User user) {
// ... do some stuff
}
or if the request attribute name does not match the method parameter name:
#RequestMapping(value = "someurl", method = RequestMethod.GET)
public String handleSomeUrl(#RequestAttribute(name="userAttributeName") User user) {
// ... do some stuff
}
I think what you are looking for is:
#ModelAttribute("attr_name") MyClass obj
You can use that in the parameters for a method in your controller.
Here is a link a to question with details on it What is #ModelAttribute in Spring MVC?
That question links to the Spring Documentation with some examples of using it too. You can see that here
Update
I'm not sure how you are setting up your pages, but you can add the user as a Model Attribute a couple different ways. I setup a simple example below here.
#RequestMapping(value = "/account", method = RequestMethod.GET)
public ModelAndView displayAccountPage() {
User user = new User(); //most likely you've done some kind of login step this is just for simplicity
return new ModelAndView("account", "user", user); //return view, model attribute name, model attribute
}
Then when the user submits a request, Spring will bind the user attribute to the User object in the method parameters.
#RequestMapping(value = "/account/delivery", method = RequestMethod.POST)
public ModelAndView updateDeliverySchedule(#ModelAttribute("user") User user) {
user = accountService.updateDeliverySchedule(user); //do something with the user
return new ModelAndView("account", "user", user);
}
Not the most elegant, but works at least...
#Controller
public class YourController {
#RequestMapping("/xyz")
public ModelAndView handle(
#Value("#{request.getAttribute('key')}") SomeClass obj) {
...
return new ModelAndView(...);
}
}
Source : http://blog.crisp.se/tag/requestattribute
From spring 3.2 it can be done even nicer by using Springs ControllerAdvice annotation.
This then would allow you to have an advice which adds the #ModelAttributes in a separate class, which is then applied to all your controllers.
For completeness, it is also possible to actually make the #RequestAttribute("attr-name") as is.
(below modified from this article to suit our demands)
First, we have to define the annotation:
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.PARAMETER)
public #interface RequestAttribute {
String value();
}
Then we need a [WebArgumentResolver] to handle what needs to be done when the attribute is being bound
public class RequestAttributeWebArgumentResolver implements WebArgumentResolver {
public Object resolveArgument(MethodParameter methodParameter, NativeWebRequest nativeWebRequest) throws Exception {
// Get the annotation
RequestAttribute requestAttributeAnnotation = methodParameter.getParameterAnnotation(RequestAttribute.class);
if(requestAttributeAnnotation != null) {
HttpServletRequest request = (HttpServletRequest) nativeWebRequest.getNativeRequest();
return request.getAttribute(requestAttributeAnnotation.value);
}
return UNRESOLVED;
}
}
Now all we need is to add this customresolver to the config to resolve it:
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
<property name="customArgumentResolver">
<bean class="com.sergialmar.customresolver.web.support.CustomWebArgumentResolver"/>
</property>
</bean>
And we're done!
Yes, you can add your own 'binders' to the request attribute - see spring-mvc-3-showcase, or use #Peter Szanto's solution.
Alternatively, bind it as a ModelAttribute, as recommended in other answers.
As it's the logged-in user that you want to pass into your controller, you may want to consider Spring Security. Then you can just have the Principle injected into your method:
#RequestMapping("/xyz")
public String index(Principal principle) {
return "Hello, " + principle.getName() + "!";
}
In Spring WebMVC 4.x, it prefer implements HandlerMethodArgumentResolver
#Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.getParameterAnnotation(RequestAttribute.class) != null;
}
#Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
return webRequest.getAttribute(parameter.getParameterAnnotation(RequestAttribute.class).value(), NativeWebRequest.SCOPE_REQUEST);
}
}
Then register it in RequestMappingHandlerAdapter
I want to read a domain object (UserVO) from session scope.
I am setting the UserVO in a controller called WelcomeController
#Controller
#RequestMapping("/welcome.htm")
public class WelcomeController {
#RequestMapping(method = RequestMethod.POST)
public String processSubmit(BindingResult result, SessionStatus status,HttpSession session){
User user = loginService.loginUser(loginCredentials);
session.setAttribute("user", user);
return "loginSuccess";
}
}
I am able to use the object in jsp pages <h1>${user.userDetails.firstName}</h1>
But I am not able to read the value from another Controller,
I am trying to read the session attribute as follows:
#Controller
public class InspectionTypeController {
#RequestMapping(value="/addInspectionType.htm", method = RequestMethod.POST )
public String addInspectionType(InspectionType inspectionType, HttpSession session)
{
User user = (User) session.getAttribute("user");
System.out.println("User: "+ user.getUserDetails().getFirstName);
}
}
The code you've shown should work - the HttpSession is shared between the controllers, and you're using the same attribute name. Thus something else is going wrong that you're not showing us.
However, regardless of whether or not it works, Spring provides a more elegant approach to keeping your model objects in the session, using the #SessionAttribute annotation (see docs).
For example (I haven't tested this, but it gives you the idea):
#Controller
#RequestMapping("/welcome.htm")
#SessionAttributes({"user"})
public class WelcomeController {
#RequestMapping(method = RequestMethod.POST)
public String processSubmit(ModelMap modelMap){
User user = loginService.loginUser(loginCredentials);
modelMap.addtAttribute(user);
return "loginSuccess";
}
}
and then
#Controller
#SessionAttributes({"user"})
public class InspectionTypeController {
#RequestMapping(value="/addInspectionType.htm", method = RequestMethod.POST )
public void addInspectionType(InspectionType inspectionType, #ModelAttribute User user) {
System.out.println("User: "+ user.getUserDetails().getFirstName);
}
}
However, if your original code isn't working, then this won't work either, since something else is wrong with your session.
#SessionAttributes works only in context of particular handler, so attribute set in WelcomeController will be visible only in this controller.
Use a parent class to inherit all the controllers and use SessionAttributes over there. Just that this class should be in the package scan of mvc.
May be you have not set your UserVO as Serializable.