spring:bind error when converting empty input field to Long

[Paul Taylor]

I am using a SimpleFormController with Spring:bind tag on my jsp and a validator object.

I have a simple Long property which maps to a simple input field, it validates numbers ok but if no value is entered at all it throws a conversion error.

Please how do I handle this simple case, surely I dont have to write a property editor for this.

[lumpynose]

Where is it throwing? In the validator or in the view?

Can you show us the code where it's throwing?

[rstearns01]

By default, the CustomNumberEditor doesn't accept empty/null input. Put the following line in your controller initbinder() method:

binder.registerCustomEditor(Long.class, new CustomNumberEditor(Long.class, true));

[Paul Taylor]

I tried that and was pretty confident it would solve the prpblem but it hasnt actually made any difference, the exact error I get is:
Failed to convert property value of type [java.lang.String] to required type [java.lang.Long] for property 'volume'; nested exception is java.lang.NumberFormatException: For input string: " "

[Paul Taylor]

Sorry I had only done a deploy not a real build, it has made a difference but code now falls over when I call ValidationUtils in my validator to validate the field, I will try subclassing the CustomNumberEditor

[Paul Taylor]

ok, problem solved by creating the following class and registering it with initBinder

import org.springframework.beans.propertyeditors.CustomNumberEditor;
import org.springframework.util.NumberUtils;
import org.springframework.util.StringUtils;

public class LongAllowsBlanksEditor extends CustomNumberEditor
{
    public LongAllowsBlanksEditor()
    {
        super(Long.class, true);
    }

    /**
     * Parse the Number from the given text, using the specified NumberFormat.
     */
    public void setAsText(String text) throws IllegalArgumentException
    {
        super.setAsText(text);
        if(getValue()==null)
        {
            setValue(new Long(0));            
        }       
    }
}