I have a quick question about how to use the Spring MVC.
I just started with it and i was used to have pages that always had their data loaded calling some controller that you setted ON THE PAGE.. calling some methods on controllers to load objects at the page at load time.
Is it the same in Spring MVC? Cuz what im seeing so far is that if you want to load a page with data, you always have to use a modelandview object which is loaded by a method that you must call before... and them you return the modelandview object with its destination to the view that you want.
What im trying to know is if there is a way that the page requests some data from the controller before it gets loaded... automatically...
Dont know if im making my self clear... thanks anyway for the help!
in spring mvc, using Controllers, it is always Request->Controller(populates model and chooses view)->Response.
you could use ajax to load data from any resource (even Controllers) or jsp:useBean to explicitly call some business logic or jsp:include to include a certain fragment or a custom jsp tag.
I also face the same situation.
check the below link for getting the data from the controller before view(JSP) load.
how to load the data into index page
Related
I am creating a spring boot server, and I would like the initial page (index.jsp) to be a datatable with information coming from the redis database. Anyone know how to do this with javascript or inside jsp pages?
First of all JSPs are outdated technology so I recommend you to go for thymeleaf which is a perfect choice with spring boot instead of JSP.
JAVA approach :
Just create a mapping with / base url and fetch Redis data using normal approach and use it in UI.
GetMapping("/")
public String index(){
//Fetch Redis data here add into model attributes
return "index";
}
JavaScript/inside JSP approach :
You can create a mapping method with some url like above and make an AJAX call on page load from the JSP page and get the JSON format data and use it.
Don't forget to put #ResponseBody annotation on top of the method which will return the data(JSON) instead of the page.
Refer call ajax to spring controller
I need to do forEach over lazy collection in jsp from spring controller. But this invocation crashes because session was closed in controller. I solve this by loding collection via:
Hibernate.initialize(obj.getCollection())
Is it possible to tune mvc to have hibernate session inside jsp?
Thanx
But this invocation crashes because session was closed in controller
I assume by crash you mean that you caused a LazyInitializationException by accessing a mapped collection after the session was closed.
Tuning mvc to have Hibernate session inside you JSP essentially means that you want to hold the session open for the duration of your HTTP request. This means that at render time you can still load the data you require.
You can achieve this using the open session in view pattern. In Spring this is implemented using the OpenSessionInViewFilter. See this answer for more detail on setting it up.
The alternative as you have already demonstrated it to load the data that you require within the transaction which loaded the parent. This is why Hibernate supports lazy loading. Sometimes you will need to load child entities and collections but sometimes you don't. By mapping it as lazy you can choose depending on the specific interaction.
I'm developing a web server using MVC with multiActionController. However, now I want to handle any request (/*) with a Front Controller. After that, this Front Controller will forward this request to the View in ModelAndView. However, after many searches with Google, I still don't know how to implement it.
I appreciate your help.
In that case you need to have a controller class defined with the annotation #RequestMapping("/")
and one function which will catch the GET request for the same mapping and from that function you can return whatever model and view you want to return.
Hope this helps you.
Cheers.
I primarily use annotated controllers that return ModelAndView object used by Spring and Freemarker to render and return pages to browsers - works great. I'd now like to respond to ajax gets and posts that return html fragments as payload inside an XML message.
The problem I'm having not returning a ModelAndView objects seems to confuse Spring WRT to #ModelAttribute (s) and session objects that support data to / and from forms.
I've had to hack the freemarker template to support i18n messages, etc. I'm finding that simply rendering an FTL file while also trying to utilize Spring's object rendering from froms is becoming quite a rabbit hole.
I'm trying to manually (guess what and) do the things that get done behind the scenes and it's not working optimally. To edit an object I'm manually placing the object in the session on rendering the edit form. When the post comes back there are residual/different values in the object I get back out of the session AND the ModelAttribute that Spring rendered for me.
Bottom line? Questions about Spring, Freemarker and custom non-ModelAndView responses that are rendered by Freemarker.
Add another instance of FreeMarkerViewResolver that only that has viewNames ='*.frg'. The viewClass should be your own class that renders the template the way you want by overriding the processTemplate method.
The real question: Is there a way to clear certain attributes for all components on an initial page load?
Background info:
In my application, I have a JSF 2.0 frontend layer that speaks to a service layer (the service layer is made up of Spring beans that get injected to the managed beans).
The service layer does its own validation, and I do the same validation in the frontend layer using my own validator classes to try and avoid code duplication somehow. These validator classes aren't JSF validators, they're just POJOs.
I'm only doing validation on an action, so in the action method, I perform validation, and only if it's valid do I call through to the service layer.
When I do my validation, I set the styleClass and title on the UIComponents using reflection (so if the UIComponent has the setStyleClass(:String) or setTitle(:String) methods, then I use them).
This works nicely, and on a validation error I see a nicely styled text box with a popup containing the error message if I hover over it. However, since the component is bound to a Session Scoped Managed Bean, it seems that these attributes stick. So if I navigate away and come back to the same page, the styleClass and title are still in the error state.
Is there a way to clear the styleClass and title attributes on each initial page load?
Thanks,
James
P.S. I'm using the action method to validate because of some issues I had before with JSF 1.2 and it's validation methods, but can't remember why... so that's why I'm using the action method to validate.
Ok, so I must use a PhaseListener, see this blog entry by BalusC and this other blog entry, that's a much better way of doing what I'm doing already - setting the styleClass manually using reflection - which gets all components with messages and highlights them... I'm gonna do the same, however think it's possible to add an attribute instead, haven't tried it yet.