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First of all JSPs are outdated technology so I recommend you to go for thymeleaf which is a perfect choice with spring boot instead of JSP.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
Related
I am currently working on a Spring Boot project and I am fairly new to template engines. This will also be my first own private project with Spring Boot.
I would like to know whether it is necessary to include a template engine, such as Thymeleaf, while developing a web application with Spring Boot. I'm using PostegreSQL for the database.
I read under another post that a template engine is not needed, if the backend framework uses JSON for data exchange, because template engines are for rendering retrieved data to HTML for the client. I retrieve JSON objects from the database, can I leave template engines out of my project then?
If any more details are needed, leave a comment below.
No they aren't necessary, in fact most new projects that require web-pages are using single page applications now like Angular, React, Vue, ... over thymeleaf or jsp.
Aside from that a Spring project doesn't always need web pages, for instance when you are just creating a REST API for other applications to call on, or when you are automating things like: a mail service / printing / ... You name it.
However, when you DO want a simple solution with some pages that aren't all that dynamic or complex, pivotal / VMware does recommend to use thymeleaf (over jsp and other solutions) because it integrates easily.
I read under another post that a template engine is not needed, if the backend framework uses JSON for data exchange, because template engines are for rendering retrieved data to HTML for the client. I retrieve JSON objects from the database, can I leave template engines out of my project then?
This is partly true. Yes, Thymeleaf and alike are mostly intended to render data to HTML. They can render any text data, including JSON, but there are tools better suited for the job. On other hand it does not matter how you store the data in your database or what database you are using. You can't just skip rendering (serializing) the response so it does not matter how you store it. What matters is what you want to return as response. For HTML Thymeleaf or even JSP are suitable, but for JSON you may want to use Jackson or Gson instead.
You didn't mentioned the technology you are going to use, so for my examples I'll assume you intend to use Spring Web MVC. Lets take a look at "traditional" controller:
#Controller
public class GreetingController {
#GetMapping("/greeting")
public ModelAndView greeting(#RequestParam(value = "name", defaultValue = "World") String name) {
return new ModelAndView("greeting", "greeting", new Greeting(name));
}
}
When you make GET request to "/greeting", Spring will call greeting and get the object it returns. In this case it contains the model (the data we want to render) and the view (the template file to use). Then it will try to find a view (something like greeting.html or greeting.jsp) and use template engine like Thymeleaf (or whatever else is configured) to render it (typically to HTML).
What if we want to return JSON instead? In this case we need to:
modify greeting to return Greeting instance instead of ModelAndView
Use RestController instead of Controller. This will tell Spring MVC that we want to directly serialize the object returned to JSON (or similar format) instead of using template to do that.
Here is the modified example:
#RestController
public class GreetingController {
#GetMapping("/greeting")
public Greeting greeting(#RequestParam(value = "name", defaultValue = "World") String name) {
return new Greeting(name);
}
}
Spring MVC still needs some help to serialize the Greeting instance to JSON. But if you use Spring Boot and the web starter, you don't have to worry about it. It will include Jackson for you.
This is in no way exhaustive answer. As a matter of fact it skips a lot of details, but I hope nevertheless it is useful one. If you want to create REST API using JSON, this Building a RESTful Web Service guide is a good place to start. If you follow the Starting with Spring Initializr steps you'll get a project setup with only what is needed (well maybe with a bit extra but I would not worry too much about it).
I am using Spring Boot 1.5.4 (Spring MVC) and Thymeleaf 3.0.6 (Layout Dialect 2.2.2)
Assume that I am rendering the model from a Spring MVC Controller method with a Thymeleaf template (template A), which outputs HTML A.
Is it possible, from within template A, to call/invoke another Spring MVC controller method (which then will render the model with a different thymeleaf template) outputting HTML B, and load the rendered results into HTML A?
Something like what the struts2 action tag does with the executeResult=true Param.
https://www.tutorialspoint.com/struts_2/struts_action_tag.htm
I've looked into thymeleaf include and replace, but they only seem to work with loading the html fragment not an entire Spring MVC Request
You can try to make an AJAX request to the Spring MVC controller method which will return the template B.
Then, once you have the response you can set the response as an existing html element in your DOM, something like:
$.get("your_end_point", function(data, status){
document.getElementById("your_template_B_Container_DIV_ID").appendChild(data);
});
This is only a guess, also keep on mind that if you create a template with body, head... this will probably not work, try to use a template with no body or head tags. For example you can try with a template made only with div tags ans see if you can render it.
I'm migrating a Play! 1.2 web application and moving to Spring Boot + Spring MVC. Some views contain URLs to other endpoints. For example, I display the book title on the page and next to it I want to add the URL to go the book's details page (e.g. localhost/books/{id}).
In Play! 1.2 the controllers are static, and there is also a Router which can create the full URL for a method belonging to another controller (Router.getFullUrl("BookController.bookDetails", args)), but how do I achieve this with Spring MVC?
Best regards,
Cristian.
If you are trying to get the app/deployed name automatically in .jsp files to make the urls, then please make use of context path. An example below :
<c:set var="context" value="${pageContext.request.contextPath}" />
<script src="${context}/themes/js/jquery.js"></script>
From your requirement "admin.myapp.com","admin-test.myapp.com" are server names right? Something like http://admin.myapp.com/book/{bookId},http://admin-test.myapp.com/book/{bookId}. In Spring app, relative path in jsp can be accessed using pageContext.request.contextPath
I also found the UriComponentsBuilder and ServletUriComponentsBuilder. They are similar to the Play! Framework router and provide methods for building URI's, handling parameters and the query etc. We chose to annotate the controllers' methods using constants and then use the same constants with the UriComponentsBuilder to build back the path and create the request query for GET requests.
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
I am developing my site in Spring MVC with Sitemesh.
Dynamic content is changed oon every page, Menu and Footer I can include in template definition. But there comes a problem. On every site below the dynamic content there should be a news list with loaded some news from my DB. I created my #Controller and it loads 5 latest news, but how to add this on my template? What request mapping should implement my news controller?
I don't kwow how Sitemesh works, but I solved problems like that by using interceptor:
create a class that extends : HandlerInterceptorAdapter
Override the method postHandle and populate the modelAndView Object like this :
modelAndView.addObject("newslist",myNewsList);
So you will have a variable $newslist injected into all your views.
Don't forget to declare bean in your mvc-congig.xml :
<bean id="newsListInterceptor" class="mypackage.NewsListInterceptor"/>
As the interceptor is executed for each request I also use ehcache to store the result and avoid during a select in database for each call.