Binding Arrays with Spring

1
Binding Arrays with Spring

• Presented by Thomas Fischer
• Powered by the Love of Code
• Sponsored by Nobody
• Generously Supported by Almon Deomampo

2
Binding Goals

• Goals
• Have a composite command object that contains
  arrays (primitive arrays and collections).
• Update them as well using Spring binding (,
  rather then by hand).

3
A Simple Form Controller

• public class BindDemoController extends
  SimpleFormController
• protected Object formBackingObject(HttpServlet
  Request httpServletRequest) throws Exception
• System.out.println("formBackingObject
  called")
• DemoCommand cmd new DemoCommand()
• cmd.setName("Sky Captain")
• cmd.getFuzzyItems().add("Rosy Cloud")
• cmd.getFuzzyItems().add("Fluffy Cloud")
• cmd.setShinyItems(new String"sun
  glasses", "more sun glasses")
• return cmd
• protected ModelAndView onSubmit(Object obj)
  throws Exception
• System.out.println("onSubmit called")
• return new ModelAndView(getFormView(),
  "cmd", obj)

• public class DemoCommand
• private String name
• private ArrayList fuzzyItems new
  ArrayList()
• private String shinyItems new String0
• public ArrayList getFuzzyItems()
• return fuzzyItems
• public void setFuzzyItems(ArrayList
  fuzzyItems)
• this.fuzzyItems fuzzyItems
• public String getName()
• return name
• public void setName(String name)
• this.name name

4
Binding Arrays for Display

• lt_at_ page contentType"text/htmlcharsetUTF-8"
  language"java" gt
• lt_at_ taglib prefix"c" uri"http//java.sun.com/jst
  l/core" gt
• lt_at_ taglib prefix"fmt" uri"http//java.sun.com/j
  stl/fmt" gt
• lthtmlgt
• ltheadgtlttitlegtSpring Bind Demolt/titlegtlt/headgt
• ltbodygt
• lth1gtDemonstrate Spring Binding for
  Arrayslt/h1gt
• ltform action"bind.htm" method"post"gt
• lttable border"1"gtlttrgtlttdgtFuzzylt/tdgtlt/trgt
• ltcforEach var"thing"
  items"cmd.fuzzyItems"gt
• lttrgt
• lttdgt
• ltcout value"thing"/gt
• lt/tdgt
• lt/trgt
• lt/cforEachgt
• lt/tablegt

5
Binding Arrays for Update

• lttable border"1"gtlttrgtlttdgtFuzzylt/tdgtlt/trgt
• ltcforEach var"thing"
  items"cmd.fuzzyItems" varStatus"loopStatus"gt
• lttrgt
• lttdgt
• ltspringbind
  path"cmd.fuzzyItemsloopStatus.index"gt
• ltinput type"text"
  name"ltcout value"status.expression"/gt"
  value"ltcout value"status.value"/gt"/gt
• lt/springbindgt
• lt/tdgt
• lt/trgt
• lt/cforEachgt
• lt/tablegt

6
Notes

• Tricky Points
• When using the Spring bind tag, use the full path
  of the command name. (Spring cant work with the
  loop item of the JSTL forEach.)
• The command object itself can NOT be an array. If
  there is an array of command objects, they have
  to be placed inside a container class.
• Issues
• Using Spring binding gives a malicious user a lot
  of power to change any field and value of the
  command object.
• The order of the arrays have to stay constant
  between presentation and submission of the form.
  Otherwise, data can be corrupted.