Styjun

I have a Spring MVC application using forms. The form contains a dynamic list of filters which can be added or removed. My form object simply looks like this:

public class RequestForm 
 @Valid
 List<Filter> filters = new LinkedList<>();

Filter is a base class and has other subclasses to allow custom validation of the value:

public class Filter 
 String type;
 String value;
 boolean ignoreFilter;
 

public IntFilter extends Filter 
 @ValueIsInteger
 String getValue() ...


public DateFilter extends Filter 
 @ValueIsDate
 String getValue() ...

In my controller I am using @InitBinder to cast the Filter objects into the right subclass based on the type attribute and ignore the filter based on the other attribute. The code looks like this:

@InitBinder
public void initBinder(WebDataBinder webDataBinder, HttpServletRequest httpServletRequest) 
 // Filter out all request when we have nothing to do
 Object nonCastedTarget = webDataBinder.getTarget();

 // TODO: Better cache this in static final field instead
 Pattern pattern = Pattern.compile("filters\[(\d+)]\.filterType");

 Map<Integer, String> types = new HashMap<>();
 Enumeration<String> parameterNames = httpServletRequest.getParameterNames();
 while (parameterNames.hasMoreElements()) 
 String element = parameterNames.nextElement();
 Matcher matcher = pattern.matcher(element);
 if (!matcher.matches()) 
 continue;
 

 types.put(
 Integer.parseInt(matcher.group(1)),
 httpServletRequest.getParameter(element)
 );
 


 RequestForm target = (RequestForm) nonCastedTarget;

 types.keySet().stream().sorted().forEach(key -> 
 //remove disabled filter if("false".equals(httpServletRequest.getParameter("filters["+key+"].ignoreFilter"))) 
 switch (types.get(key)) 
 case "int":
 target.getFilters().add(new IntFilter(httpServletRequest.getParameter("filters["+key+"].value")));
 break;
 case "date":
 target.getFilters().add(new DateFilter(httpServletRequest.getParameter("filters["+key+"].value")));
 break;
 default:
 throw new IllegalStateException("Unknown type: " + types.get(key));
 
 
 );

And in the controller:

 public ModelAndView postPage(@Valid @ModelAttribute("requestForm") RequestForm requestForm, BindingResult bindingResult, Locale locale) 

 ModelAndView mav;

 // errors in the selection
 if (bindingResult.hasErrors()) 
 mav = new ModelAndView("requestmanagement/view");
 addRequestFormParameters(mav, requestForm, locale);
 return mav;
 
 ...

My Problem:

The casting and validation of subfilters works. However, ignored filters are still added to the RequestForm in the controller. If my form contains an IntFilter which should be ignored, my RequestForm in the controller contains still the filter but is not casted into the subtype.

Who can I remove the filter from the RequestForm?