I'm new to java and web apps and after trying out a few things I went with a set up of Spring webmvc using annotations and velocity as templating engine. It's not that hard to do simple #RequestMapping annotations to controller methods and returning ModelAndView instances filled with data, however I was wondering how things are done when you have data you need in the model that occurs on every page, for example "latest 5 news items" or something similar. You could of course always fill the model with such data in every method that is handled by a #RequestMapping, but I'm quite sure that that is not the way to do it.
What is the correct way of filling the model with recurring data, without poluting your controller methods with calls to the same method for this recurring data.
Any help is appreciated.
You could use a servlet filter or a Spring interceptor, and get the recurring data from this filter or interceptor and place it in a request attribute.
Another solution is to let the page call more than one controller, for example by using multiple ajax requests. Then one controller could is responsible for the specific page and another is responsible for "latest 5 news items", see related question.
Good question dude. In my current app i am using sessions to store my username which is appearing on all the rest of the app.
#JB Nizet thanks for the link.. now ill go for spring interceptor
Related
Stack: SpringBoot, Spring MVC and Thymeleaf
I followed https://spring.io/guides/gs/serving-web-content/
I would like now to do a loop for which each iteration updates the ${name} in the view. (without calling multiple time the controller).
I would say I want to make the page/view dynamic? But I miss the vocabulary of it and therefor I can't find a proper way to do it.
Anyone knows how ?
See you thanks.
Send the list from your controller to the requested html page and then use th:each on your html page to populate the values.
I'm having trouble understanding and then deciding how I want setup the frontend of my spring boot application. My question is do I even need thymeleaf or rather do I lose something if I only use vuejs?
First things first I am mostly into backend stuff and barely know a lot about current frontend technologies etc. However I tried out vuejs and liked it a lot.
I used to use thymeleaf and serve static html pages with thymeleaf markup. After playing around a bit with vuejs I want to use that instead.
So far I've managed to set it up two ways:
I keep thymeleaf and use it together with vuejs. This allows me to keep the model that I can pass in my view controllers.
I only use vuejs and get all information through REST from the spring boot app. However I am asking myself if there isnt a way to access the model from here? If that would be the case I wouldnt need thymeleaf right?
I really think that I'm having some kind of architectural misunderstanding and would appreciate it if I could get it cleared up.
Thank you in advance
I need to create a project able to render views (with JSP) and I need to provide a REST API too.
It's possible to have all of this in the same project?
How will the URLs works to access each things?
Thanks you!
If you are trying to follow the strict Roy Fielding-like principles of REST, then probably not.
But if you just want a REST API in a loose meaning, lets say an interface that returns a resource (JSON, HTML, a documents, etc.), sure. Think of it this way. Most web applications (ones that render views) are also going to have some form of AJAX calls, AJAX calls are just calling a REST API (~ish) that returns some JSON (or something) and then JavaScript is going to parse the response and render something on the views.
So, most modern websites that are powered by or assisted by AJAX are going to be a mix of a REST API and a view rendering one.
Hehe. I just made REST developers around the world cringe.
Now, is this a good practice? That is a whole other story. If you are talking about about a large application that is a GUI based and a large application that uses a REST API, normally you don't mix them. Things get confusing and modularity is awesome for maintenance. Also for what it is worth, normally if you are going 100% RESTful, technology you may need for UI development are no longer available since you begin to track state and such. But if its something small or UI related go for it!
As for the URLs, think about this. You tagged Spring so, I am using that.
//I will render a view!
#RequestMapping("/blah")
public String blah(Model model){
return "/view/blah";
}
//I return a JSON string of "/view/blah"
#RequestMapping("/blah")
public #ResponseBody String blah(Model model){
return "/view/blah";
}
Both of these would be inside a #Controller, they are both doing the same thing but the #ResponseBody in a very, very loose sense, makes the second a REST service, as it tells Spring that what you are returning is the response and not to render a view from it. Granted Spring will only try to render a view if you have a ViewResolver set up.
Baeldung has a great breakdown of RESTful controllers versus non in Spring, and yes they can be used in the same application.
Hopefully that helps!
Yes you can mix in an application a classic #Controller with a configuration that provides a view based on JSP and a #RestController that, as you can read from official javadoc, is a
A convenience annotation that is itself annotated with #Controller and
#ResponseBody.
Yes, you can, only have precaution about the url that you configure in your controllers, with #RequestMapping configure the correct URL for every path in your application.
I have a spring mvc application. Now in my project, I basically want to execute the latest request and all the previous requests are cancelled/terminated.
Currently all the cancellation code is inside my controller. But for code clarity/readability I want to port this code outside my controller. Ultimately I want a layer above, which takes requests, checks if the task is to be cancelled or not and only then forward it to the controller.
One way of doing above would be to have another controller which forwards it to the above controller. I have also heard of Handler Interceptor. What is the best way of doing it?
I would go with an interceptor if I were you.
you can check this link for examples on how to implement you own
In it's simplest form, I want an interceptor that checks session data to see if a user is logged in, and if not redirects them to the login page. Obviously, I wouldn't want this interceptor to be used on say the welcome page or the login page itself.
I've seen a design that uses a listing of every url to one of two interceptors, one doing nothing and the other being the actual interceptor you want implemented, but this design seems very clunky and limits the ease of extensibility of the application. It makes sense to me that there should be an annotation-based way of using interceptors, but this doesn't seem to exist.
My friend has the idea of actually modifying the handler class so that during each request it checks the Controller it is mapping the request to for a new annotation we would create (ex #Interceptor("loginInterceptor") ).
A major point of my thinking is the extensibility, because I'd like to later implement similar interceptors for role-based authentication and/or administration authentication.
Does it sound like my friend's approach would work for this? Or what is a proper way of going about doing this?
Use Spring Security.
Please have a look at these sites, Spring Framework Annotation-based Controller Interceptor Configuration and
Ability to restrict HandlerInterceptors to specific controller paths
Hope it will be useful.
What about a Servlet Filter on all requests that sends the user to the login page if the user object isn't in the session? For the second part you can use security annotations on the controller methods that can check the user's role.