Passing a new object in Spring MVC model.addAttribute() method

Question

I am implementing the Spring PetClinic Project from here

http://docs.spring.io/docs/petclinic.html

I have a small doubt, the user clicks the find owner page from the welcome page.

Controller code which handles the request

@RequestMapping(value = "/owners/search", method = RequestMethod.GET)
    public String setupForm(Model model) {
        model.addAttribute("owner", new Owner());
        return "owners/search";
    }

Now the control is moved to the Search.jsp page, which also allows the user to add a new owner.

My doubt is why in the model.addAttribute a new owner object is put?.

model.addAttribute("owner", new Owner());

What is the need for that?. Why doesn't the flow directly navigated to Search.jsp

The Owner class has the properties of the owner like firstName, lastName. etc.

Please advice if you need any more information in the code. I will put it here.

Search.jsp

<%@ include file="/WEB-INF/jsp/includes.jsp" %>
<%@ include file="/WEB-INF/jsp/header.jsp" %>


<h2>Find Owners:</h2>

<spring:url value="/owners" var="formUrl"/>
<form:form modelAttribute="owner" action="${fn:escapeXml(formUrl)}" method="get">
  <table>
    <tr>
      <th>
        Last Name: <form:errors path="*" cssClass="errors"/>
        <br/> 
        <form:input path="lastName" size="30" maxlength="80" />
      </th>
    </tr>
    <tr>
      <td><p class="submit"><input type="submit" value="Find Owners"/></p></td>
    </tr>
  </table>
</form:form>

<br/>
<a href='<spring:url value="/owners/new" htmlEscape="true"/>'>Add Owner</a>

<%@ include file="/WEB-INF/jsp/footer.jsp" %>

Thanks. I would really appreciate the help.

Sotirios Delimanolis · Accepted Answer · 2013-12-14 14:49:14Z

4

Spring's form tag library's <form:form> element requires a model attribute to bind to to create its paths.

<form:form modelAttribute="owner"

The modelAttribute attribute is pointing to the Owner model attribute you added. It obviously doesn't use it for its value (it's empty after all). However, it uses the empty object as a template (for example, field names) for generating the name attributes of the <input> elements.

answered Dec 14, 2013 at 14:49

Sotirios Delimanolis

281k62 gold badges718 silver badges744 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Passing a new object in Spring MVC model.addAttribute() method

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related