CODEWITHSUNDEEP
javaspringspring-mvcmodel-binding
Amir Pashazadeh
Amir Pashazadeh

Reputation: 7302

How to populate multiple beans in a request using Spring @MVC

I'm developing a project using Spring @MVC (with MVC annotations).

If all request parameters shall be populated to a single bean everything seems fine, but what about multiple POJOs?

I have searched the web and am aware of form-backing-objects, but how can I use them in @MVC (annotation-based)?

Another question: shall I construct a bean for each form? Doesn't it just look like Strut's ActionForms? Is there anyway to prevent creating these objects?

Is there a way, to put all beans in a Map and ask Spring binder to populate them? Something like:

map.put("department", new Department());
map.put("person", new Person());

so department.name and department.id bind into department bean, and person.name, person.sex and ... populate in the person bean? (So the controller method accepts a Map as its parameter).

Upvotes: 2

Views: 4131

Answers (2)

Sandeep Panda
Sandeep Panda

Reputation: 16

If you give Person a reference of Department then it will be easy. In your app, if the person works in a department it will be logical to create a Has-A relationship in your Person class like this:

@Component
@Scope("prototype")
public class Person {
    private String firstName;

    private Department department;

    public Department getDepartment() {
        return department;
    }
    public void setDepartment(Department department) {
        this.department = department;
    }
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
}

You can create a Controller that gets a Person bean from the Context and renders a view.

@Controller
public class TestController implements ApplicationContextAware{

    private ApplicationContext appContext;

    @RequestMapping(value="/handleGet",method=RequestMethod.GET)
    public String handleGet(ModelMap map){
        map.addAttribute("person", appContext.getBean("person"));
        return "test";
    }
    @RequestMapping(value="/handlePost",method=RequestMethod.POST)
    public @ResponseBody String handlePost(@ModelAttribute("person") Person person){
        return person.getDepartment().getDepartmentName();
    }

    @Override
    public void setApplicationContext(ApplicationContext appContext)
            throws BeansException {
        this.appContext=appContext;
    }
}

Then inside your JSP view you can write something like this:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="sf" uri="http://www.springframework.org/tags/form" %>    
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Test</title>
</head>
<body>
    <sf:form commandName="person" action="/appname/handlePost.html" method="post">
        <sf:input path="firstName"/>
        <sf:input path="department.departmentName"/>
        <sf:button name="Submit">Submit</sf:button>
    </sf:form>
</body>
</html>

Upvotes: 0

gerrytan
gerrytan

Reputation: 41123

Form backing objects are not mandatory, you can use @RequestParam annotation to obtain the form values directly. See Binding request parameters to method parameters with @RequestParam on Spring Manual.

I don't think Map is a supported by the default Spring MVC type converters, but you can register a custom converter. See Customizing WebDataBinder initialization.

Upvotes: 2

Related Questions