I'm a php programmer now doing a Java web project using Spring framework. I'm trying to organize my JSP files the way i would have organized my .tpl files in php.
So if it would have been php i would have done it like this:
index.tpl
includes one of layout.tpls (ajax.tpl, mobile.tpl, general.tpl, simplified.tpl . . .)
includes the header of the page
includes menus
includes the actual content of the page
includes the page footer
then from the php controller i would be able to do something like this:
setLayout('general');
showTopMenu(false);
setContent('mySexyPage');
beside that i would have organized my stuff so that my views (tpl files) will be organized in folderŅ each corresponding to a single controller. like this:
userManager
addUSer.tpl
editUser.tpl
editUserPermissions.tpl
articleManager
addArticle.tpl
editArticle.tpl
and in each controller somehow define from which folder to load my content template.
Now in Spring i have a controller with methods handling requests and each of the methods returning what the view should be. I can extend all my controllers from a single abstract class where i will create an instance of ModelAndView with all default values set, then request handling methods will add what they need to the instance their daddy already created and return it.
The problem with the above approach is that i'm not forcing the coder who's writing controllers to use the ModelAndView object i created, he way still return anything he wants from the handling method he wrote.
Is there some interface containing a method like ModelAndView getModelAndView() my daddy controller will implement so Spring will ignore whatever handler methods are returning?
Or is there some better way to do this ?
Content Template Issue
The Java world has a (more than one actually, but I'm sticking with the one I know) solution for this problem, it is called Tiles. check out section 16 of the Spring 3.0.5 Reference.
ModelAndView Issue
This is more interesting. First, you can use Model with out view and have your controllers just return the view name (i.e. return a String). I believe you want to create the initial Model somewhere. Then have each controller hander method accept an argument of type Model.
Here is what I tend to do (no claim that it is a best practice):
Have a Controller.get(Model model) method that sets the initial values.
#RequestMapping(method = RequestMethod.GET)
public String get(Model model)
{ ... set default stuff ... }
Every Handler method is a variation of this:
#RequestMapping(value = "/search", method = RequestMethod.POST)
public String search(Model model, ... other stuff as needed ...)
{ ... set stuff in model ... }
Related
I'm using Spring-Boot and Thymeleaf as a template engine.
I have a web application which has a search input that is accessible in every view to anyone (the search triggers a form submission), the form has a th:object="${searchObject}" attribute and I'm using#RequestBody in my post controller to get the object.
Now, what i did so far was adding a model.addAttribute("searchObject", new SearchObject()) to every controller and it worked just fine but it made me think, what if there is a way to share an object between the whole app that i could declare once and use everywhere .. ?
So i did a little search and found out various solutions that refers to the available contexts in a spring application.
Iv'e tried to implement few of them but couldn't figure out how.
So, is there any simple way of sharing an object between the whole app so it can be accessed inside thymeleaf without writing the same code in every controller?
I'm thinking it should look something like this
th:object="${#sharedObjects.getObjectByName(object)}"
Thanks.
You can use a #ControllerAdvice to add a model attribute in all of your controllers:
#ControllerAdvice
public class SearchObjectModelAttributeAdvice {
#ModelAttribute("searchObject")
public SearchObject searchObject() {
return new SearchObject();
}
}
Most of my experience with creating controllers with Spring are for REST controllers that consume JSON formatted requests. I've been searching for documentation on how to do testing for form submission, and so far this is how I understand it should go using MockMvc:
MvcResult result = mockMvc.perform(post("/submit")
.param('title', 'test title')
.param('description', 'test description'))
.andReturn()
However, I'm not sure how to map the form parameters to a model object. I've seen the #ModelAttribute annotation pop up in my searches but I can't figure out how it should be used for mapping. In addition, this quick start guide from the official documentation does not elaborate on how things like th:object and th:field translate to HTML and subsequently to URL encoded form.
I have my controller code similar to the following:
#PostMapping('/submit')
def submit(#ModelAttribute WriteUp writeUp) {
//do something with writeUp object
'result'
}
I discovered through trial and error that my specific problem might have been Groovy specific. There test code and the controller code, it turns out, have no issues. To reiterate, for testing form submission, use the param method through perform method of MockMvcRequestBuilders. Another thing to note is that this doesn't seem to work if content type is not specified. Here's a sample test code that works for me:
MvcResult result = webApp.perform(post("/submit")
.contentType(APPLICATION_FORM_URLENCODED) //from MediaType
.param('title', 'test title')
.param('description', 'test description'))
.andReturn()
As you can see, it's not much different from what I posted originally. The controller code is pretty much just the same, with #ModelAttribute working just fine.
The problem with my setup though was that since I was using Groovy, I assumed that getters and setters were automatically generated in my WriteUp class. Here's how the WriteUp class looked originally:
class WriteUp {
private String title
private String description
}
I haven't written code in Groovy for a while, and the last time I did, classes like the one above can be assumed to have getters and setters implicitly. However, it turns out that is not the case. To solve my specific issue, I updated the access modifier in the fields to be default (package level):
class WriteUp {
String title
String description
}
I've seen the #ModelAttribute annotation pop up in my searches but I
can't figure out how it should be used for mapping.
When you mark your writeUp object with #ModelAttribute, then the Spring container populates the parameters (like title, description, etc..) from HttpServletRequest object & injects the object to the controller method, when the request comes to the server from the client (could be a Browser or MockMvc unit test client or anything else).
Also, few other basic points for your quick understanding:
(1) Controller methods are mapped to an URI and RequestMethod (like POST/GET/DELETE/PUT et..) like shown below:
#RequestMapping(value="/submit", method=RequestMethod.POST)
public String submit(#ModelAttribute WriteUp writeUp) {
//Call the service and Save the details
model.addAttribute("Writeup details added successfully");
return "writeUpResult"; //Returns to the View (JSP)
}
(2) #ModelAttribute will be mapped to an object (like your writeUp) for http POST/PUT requests where the html formd data is part of http body.
(3) #RequestParam or #PathParam will be used for http GET requests where the parameters are part of URL (i.e., not part of http body).
You can look here for understanding the DispatcherServlet request handling & Spring MVC basic web flow.
I usually add objects in my jsp requestScopes using Controllers.
For example, if I need to list categories in "localhost/products/viewall", I simply change my ProductsController adding something like
#RequestMapping("/products/viewall")
public void viewCategories(Model model) {
List<Category> categories = service.findAllCategories();
model.addAttribute("categories", categories);
}
so, this method adds a list of categories to my requestScope.
I need to do the same, but for all the pages of the website (since the variable I need will be used in the layout of the site).
How can I add something to all the pages requestScopes with Spring?
I think you have at least two possible options for this:
Using an MVC Interceptor. With an interceptor you can perform common operations for all requests. You can extend HandlerInterceptorAdapter and add common model data in postHandle
Using the #ModelAttribute annotation within an Controller. You can use this to add common data for all request mappings within a controller. You can also use an #ControllerAdvice (with #ModelAttribute annotated methods inside) if you want provide model data to all controllers. The section Using #ModelAttribute on a method should provide some additional information for this.
I have been reading this forum for quite awhile and find it VERY useful, thank you to the contributors. I have a question that has plagded me for several weeks. And here it goes.
#RequestMapping(value="updateNote.htm",method=RequestMethod.POST)
public String updateNote(#ModelAttribute("note")NoteBean nb, BindingResult res,Model model){
daoobj.updateNote(nb.getName(),nb.getPath(), nb.getNote());
model.addAttribute("note",daoobj.getByName(nb.getName()));
return("success");
}
#RequestMapping(value="updateNote.htm",method=RequestMethod.GET)
public String updateNote(#ModelAttribute("note")NoteBean nb,Model model){
populateNoteBean();
model.addAttribute("note",daoobj.getByName(nb.getName()));
return("editNote");
}
#ModelAttribute("WHAT")
public NoteBean populateNoteBean() {
NoteBean nnb = new NoteBean();
return nnb;
}
With the method populateNoteBean() the model attribute is "WHAT". But, the name that I use is "note". So when I run the code, the NoteBean is correctly saved to the data base. My question is HOW?? It seems that the name "WHAT" should be "note" or that the model attribute is saving it as no name.
Thank for your time.
With your current code you will have two instances of your notebean in the model!
First spring invokes all modelattribute annotated methods in your controller and places the results in the model. Second it evaluates the ones from your requestmapping method.
The point of a modelattribute annotated method is that you can choose how to create your bean. Load it for example from a database.
We use this approach like that:
modelattr method (name="note")
Loads beans from db
requestmapping method with modelattr param (name="note")
Merges the note bean created by the first method with the request paramters from a submit for example and you habe directly access to the modifed one.
One nice effect:
We do not want to put hidden input fields for all attributes in a form just to be able to merge the entity with the entitymanager. This way you can have a form with only one attribute (plus one for the id to be able to fetch the entity)
Or another one:
If your note bean is an abstract class spring has no possibility to instanciate the bean because it does not know what to instanciate. You can for example add a requestparam parameter in the modelattr annotated method and decide what to do yourself.
This is very well described in the documentation. Either the reference or in the api of either controller, reqestmapping or modelattribute i believe.
I have seen many examples on how simpleFormcontroller works.
But still I have some confusion.
I want to know when formBackingObject(), referenceData(), onSubmit() methods invoked?
I dont know exact working flow of these methods?
Can anyone explain me?
Workflow is as follows and it is controlled by AbstractFormController class-
The controller receives a request for a new form (typically a GET).
Call to formBackingObject() which by default, returns an instance of the commandClass that has been configured (see the properties the superclass exposes), but can also be overridden to e.g. retrieve an object from the database (that needs to be modified using the form).
Call to initBinder() which allows you to register custom editors for certain fields (often properties of non-primitive or non-String types) of the command class. This will render appropriate Strings for those property values, e.g. locale-specific date strings.
Only if bindOnNewForm is set to true, then ServletRequestDataBinder gets applied to populate the new form object with initial request parameters and the onBindOnNewForm(HttpServletRequest, Object, BindException) callback method is called. Note: any defined Validators are not applied at this point, to allow partial binding. However be aware that any Binder customizations applied via initBinder() (such as DataBinder.setRequiredFields(String[]) will still apply. As such, if using bindOnNewForm=true and initBinder() customizations are used to validate fields instead of using Validators, in the case that only some fields will be populated for the new form, there will potentially be some bind errors for missing fields in the errors object. Any view (JSP, etc.) that displays binder errors needs to be intelligent and for this case take into account whether it is displaying the initial form view or subsequent post results, skipping error display for the former.
Call to showForm() to return a View that should be rendered (typically the view that renders the form). This method has to be implemented in subclasses.
The showForm() implementation will call referenceData(), which you can implement to provide any relevant reference data you might need when editing a form (e.g. a List of Locale objects you're going to let the user select one from).
Model gets exposed and view gets rendered, to let the user fill in the form.
The controller receives a form submission (typically a POST). To use a different way of detecting a form submission, override the isFormSubmission method.
If sessionForm is not set, formBackingObject() is called to retrieve a form object. Otherwise, the controller tries to find the command object which is already bound in the session. If it cannot find the object, it does a call to handleInvalidSubmit which - by default - tries to create a new form object and resubmit the form.
The ServletRequestDataBinder gets applied to populate the form object with current request parameters.
Call to onBind(HttpServletRequest, Object, Errors) which allows you to do custom processing after binding but before validation (e.g. to manually bind request parameters to bean properties, to be seen by the Validator).
If validateOnBinding is set, a registered Validator will be invoked. The Validator will check the form object properties, and register corresponding errors via the given Errors object.
Call to onBindAndValidate() which allows you to do custom processing after binding and validation (e.g. to manually bind request parameters, and to validate them outside a Validator).
Call processFormSubmission() to process the submission, with or without binding errors. This method has to be implemented in subclasses.
Source
For more details and diagrammatic representation to understand the flow you can refer to below link -
SimpleFormController is deprecated since Spring 3.0
In Spring 3.0 use one controller with two methods for the creation process (and a third one for the show page). It typical looks like that:
/**
* Shows a form for car creation.
*/
#RequestMapping(params = "form", method = RequestMethod.GET)
public ModelAndView createForm() {
ModelMap uiModel = new ModelMap();
uiModel.addAttribute("carCreateFormBackingObject", new CarCreateFormBackingObject()); //formBackingObject - often called command object
uiModel.addAttribute("manufactureres", this.manufactureresDao.readAll()); //referenceData
return new ModelAndView("car/create", uiModel);
}
/**
* Creates the car and redirects to its detail page.
*
*/
#RequestMapping(method = RequestMethod.POST)
public ModelAndView create(final #Valid CarCreateFormBackingObject carCreateFormBackingObject,
final BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
ModelMap uiModel = new ModelMap();
uiModel.addAttribute("carCreateFormBackingObject", carCreateFormBackingObject);
uiModel.addAttribute("manufactureres", this.manufactureresDao.readAll()); //referenceData
return new ModelAndView("car/create", uiModel);
}
Car car = this.carService.create(carCreateFormBackingObject.name, ...);
return new ModelAndView(new RedirectView("/cars/" + car.getId(), true)); //redirect to show page
}
still i want to know formBackingObject(),refernceData() method get invoked automatically by whom and when?
Back to your question "still i want to know formBackingObject(),refernceData() method get invoked automatically by whom and when?"
All these methods get invoked by SimpleFormController (and its superclass AbstractFormController), the follow the Template-Method-Pattern. - SimpleFormController defines the process and your concrete subclass "plugsin" in some hooks of this process to gain the business value.
formBackingObject in invoked by AbstractFormController when the controller needs to handle a Submit (POST), or build the Command object for the initial "new" view.
referenceData is always invoked AbstractFormController when it need to build the model for the view.
formBackingObject() method, is used when you want to take some action before rendering page. i.e. like default value in HTML components.
refereceData() method, is used for add reference data in your form, i.e. populating dropdowns
OnSubmit() method, is called whe you submit form.
But, if you are using Spring 3.0
Follow following approach using annotation
#RequestMapping(value = "/index.htm", method = RequestMethod.GET)
public String showLogin() {
return "user/login";
}
This will same as formBackingObject. and in this method use modelMap() and add reference data.
Add methods same way with method = POST which will be same as OnSubmit()
rfe folling link
http://static.springsource.org/spring/docs/2.5.x/api/org/springframework/web/servlet/mvc/SimpleFormController.html
Read Workflow.. you can simply understand your doubts..
FormBackingObjectMethod()---> #RequestMapping(requestMethod.GET)
while first time form shown to the screen formBackingObject is the reason
initBinder()---> normally used for suppose you want date field should be for example (custom date example : dd**MM***yyyy) needed means use initBinder method
onSubmit() -->#RequestMapping(requestMethod.POST)
while submitting the form onSubmit() method get called
i hope this helps