Is it too late to handle a Long-Value bound to an Input field by a custom Spring Validator?

Question

Parts of the (Java, Spring-mvc, JSP) Form input is checked by Javascript. The rest is done by a custom Validator. The problem is when the Javascript validation is prevented, such an error may be printed:

Failed to convert property value of type java.lang.String to required type java.lang.Long for property xxx; nested exception is java.lang.NumberFormatException: For input string: "x"

Is there a better way to deal with the conversion itself. When the Java-validator runs it already encounters the conversion error - or is there a possibility to check before that?

edit: the code of the Binder within the Controller..

@InitBinder
public void initBinder(WebDataBinder binder) {
   SimpleDateFormat dateFormat = new SimpleDateFormat("dd.MM.yyyy");
   dateFormat.setLenient(false);

   binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, true));
   binder.registerCustomEditor(Long.class, new CustomNumberEditor(Long.class, true));
}

but its really just standard functionality (org.springframework.beans.propertyeditors.CustomNumberEditor) and I thought there has to be a simple solution, since it seems like a common thing to have a Long Object backing some imput field and trying to get no exception out of it (or catching that one)..

score 2 · Answer 1 · edited May 23 '17 at 10:24

2

Seems that you need to implement a binder in your controller to convert from String to Long. See if this thread helps, it gives you to code to convert String to Long.

Update

binder.registerCustomEditor(Long.class, "myFieldName", new  PropertyEditorSupprt(){
    @Override
    public void setValue(Object value) {
        if(value instanceof String)
           super.setValue(new Long(value));      
    }

});

edited May 23 '17 at 10:24

Community

1
1

answered Sep 09 '11 at 10:05

Ali

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I did that (implement a binder), the problem is that binder.registerCustomEditor(Long.class, new CustomNumberEditor(Long.class, true)); already throws the exception as it gets a String. I thought there might be something to do beforhand, or to somehow override the Exception by a specific Message. – definitely undefinable Sep 09 '11 at 10:29
can you post your code for the Controller, CustomEditor and Entity? – Ali Sep 09 '11 at 16:19
posted the initBinder, part of the Controller, which is really quite simple. the rest in the Controller is Render and Action Mappings (since its Portlet-code) ..but thanks for your time. – definitely undefinable Sep 12 '11 at 10:17
Try to define your own as I've shown in my update. That way you can set a break-point to see what is going on. This will only work in your entity defines `myFieldName` as a `Long`, also to minimize headache, make sure it's the object and not the primitive `long`. I've looked at the source for `CustomNumberEditor` and it casts the `value` Object to `Number` where as it's probably being passed as a `String`. – Ali Sep 12 '11 at 11:12
alright, seems like there's no solution without an own class or at least overriding CustomNumberEditor – definitely undefinable Sep 12 '11 at 14:00
Depends, if you are using spring forms then there should be automatic casting to Long. What is your html like? – Ali Sep 12 '11 at 14:06
its a – definitely undefinable Sep 12 '11 at 14:08

score 2 · Accepted Answer · answered Sep 12 '11 at 14:06

if someone's interested .. the code of the custom Binder that worked in the end follows..

  // prevent alphanumeric/special chars in numeric string (for backing field of type Long)
  binder.registerCustomEditor(Long.class, new CustomNumberEditor(Long.class, true) {
     @Override
     public void setAsText(String value) {
        if (value != null && !value.isEmpty() && CustomValidator.isNumeric(value)) {
           super.setAsText(value);
        } else {
           super.setAsText(null);
        }
     }
  });

although, you still have to adjust your validation method so that it makes sense with text that was entered, got removed, and was changed to null!

Is it too late to handle a Long-Value bound to an Input field by a custom Spring Validator?

2 Answers2