As I mentioned earlier, I recently moved back to the Java world after a brief and enjoyable foray into Groovy & Grails. After a few minutes of becoming reacquainted with Spring MVC, I found myself wanting to make my Spring MVC app behave more like a Grails app. I’m lazy, what can I say?
The request mapping annotations are the obvious first piece to the puzzle. The second piece is using model attributes. The third is a bit of javascript to get some flexibility in the view. Here we go.
Obviously, the class marked with the ModelAttribute annotation can be an actual model object or a command object.
The controller will look something like this:
/**
* A simple controller, use it to display and update values in the command object.
*
* @author justin
*/
@Controller
public class SampleController {
@RequestMapping("/action-to-display-page.do")
public ModelAndView displayYourPage() {
//build your command object
ModelOrCommandObject modelOrCommandObject = new ModelOrCommandObject();
modelOrCommandObject.setMessage("Hello world.");
//put your command object in the model map.
ModelMap modelMap = new ModelMap();
modelMap.addAttribute("modelOrCommandObject", modelOrCommandObject);
//build your ModelAndView object.
ModelAndView modelAndView = new ModelAndView();
modelAndView.addAllObjects(modelMap);
modelAndView.setViewName("some-page.jsp");
return modelAndView;
}
/**
* One of the actions that your page is submits to.
* @param modelOrCommandObject
* @param result
* @param status
* @return
*/
@RequestMapping("/one-action-to-call.do")
public ModelAndView actionOne(
@ModelAttribute("modelOrCommandObject") ModelOrCommandObject modelOrCommandObject,
BindingResult result,
SessionStatus status) {
//do whatever you need to with your command or model object for this command
modelOrCommandObject.getMessage();
return new ModelAndView();
}
/**
* Another action that your page submits to.
* @param modelOrCommandObject
* @param result
* @param status
* @return
*/
@RequestMapping("/another-action-to-call.do")
public ModelAndView actionTwo(
@ModelAttribute("modelOrCommandObject") ModelOrCommandObject modelOrCommandObject,
BindingResult result,
SessionStatus status) {
//do whatever you need to with your command or model object.
modelOrCommandObject.getMessage();
return new ModelAndView();
}
}
We’ll have the option in the view to map one action to the controller or multiple actions. Multiple actions is easy with a bit of javascript.
The jsp will contain code like this;
<form:form action="/myapp/one-action-to-call.do" method="POST" modelAttribute="command" method="POST">
<!– some form fields –>
<button onclick="this.form.action=’/myapp/one-action-to-call.do’;submit()">One action</button>
<button onclick="this.form.action=’/myapp/another-action-to-call.do’;submit()">Another action</button>
</form:form>
That’s been working well for me as a simple bridge between Spring MVC and *some* of the convenience and efficiency of grails.
