Question

I have complex form objects, with unlimited depth and I’m trying to edit them on jsp with spring form tags.

Main modelAttribute is bind to spring form, and while I’m iterating through childs, I use nestedPath and everithing works OK. As result I have generated input names something like:

name="elements['secondColumn'][0].elements[0].removed"

Problem is that I can not know the generated name. Why I need it? Let’s say that I have delete button from which I want to set appropriate field “removed” to 1.

Update:
How does it works? I am using tag files which are recursively calling them self.

container.tag

<c:forEach items="${elements}" var="element" varStatus="index">
 <spring:nestedPath path="elements[${index.count - 1}]">
   <my:elementConfig element="${element}">
    <my:container elements="${element.elements}"/>
   </my:elementConfig>
 </spring:nestedPath>
</c:forEach>

elementConfig.tag

...
<form:hidden path="removed"/>
...
<button onclick="delete('howToGetNameOfRemovedHidden')">Delete</button>
...
<jsp:doBody/>
...

Closest match I allready found is a “nestedPath” pageContext attribute, but it contains the name of the modelAttribute (form) name too.

Is there official way to get the generated name?

Thanks

Answer 1

As it seems there is no official support for getting generated input names, so I’ve made a function which handles it. It is based on a functionality I found in Spring form tag library.

Static methods:

public class JspUtils {

    public static String escapeJS( String value) {
        return StringEscapeUtils.escapeJavaScript( value);
    }

    public static String getPath( PageContext pageContext, String name) {

        String path =   (String)pageContext.getRequest().getAttribute( "nestedPath");
        if (path == null)
            path    =   (String)pageContext.getAttribute( "nestedPath");
        if (path == null)
            return name;

        path        =   path.substring( path.indexOf( ".") + 1);
        path        +=  name;
        return path;
    }

    public static String getPathJsEscaped( PageContext pageContext, String name) {
        return StringEscapeUtils.escapeJavaScript( getPath(pageContext, name));
    }
}

tld definition:

<function>
    <description>
        Get nested path value as string
    </description>
    <name>getPath</name>
    <function-class>com.pathfix.JspUtils</function-class>
    <function-signature>java.lang.String getPath(javax.servlet.jsp.PageContext, java.lang.String)</function-signature>
</function>
<function>
    <description>
        Get nested path value as javascript escaped string
    </description>
    <name>getPathJsEscaped</name>
    <function-class>com.pathfix.JspUtils</function-class>
    <function-signature>java.lang.String getPathJsEscaped(javax.servlet.jsp.PageContext, java.lang.String)</function-signature>
</function>

Example usage:

<%@ taglib prefix="pathfix" uri="http://pathfix.com"%>

Name: <form:input path="name"/>
<a href="javascript: alert('Generated name is ${pathfix:getPathJsEscaped( pageContext, 'name')}')">Test it!</a>