java - Is there an easy way to turn empty form inputs into null strings in Spring MVC?

Question

I'm using Spring MVC and SimpleJdbcInsert to insert objects into a MySQL database. I'd like to set the blank input to NULL in the database rather than ''. I have quite a few fields, and I'm hoping for a way to do this without manually checking every value.

Thanks!

---

UPDATE

So I'm an idiot. Several errors combined on my part led me to believe the correct answers below were not correct. I'd written a PropertyEditorSupport like this:

class StringEditor extends PropertyEditorSupport {

    public void setAsText(String text) {
        String value = text.trim();
        if ("" == value) {
            setValue(null);  
        } else {  
            setValue(value);  
        }
    }

}  

There are two problems:

1. no getAsText, so my form was getting populated with "null" strings!
2. my equality check is C++, not Java. When I tried the recommended setter, I just reloaded the post, which already contained the "null" strings. Once I cleaned all that up, everything started working.

Thanks for the help, and sorry for my "operator error"!

Brett

Answer 1

The class you're looking for is:

org.springframework.beans.propertyeditors.StringTrimmerEditor

If you construct it with a true it will convert empty/whitespace strings to null. How to get it registered onto the binder depends on if you want it to be the default or only apply to certain views.

e.g., on a single controller you can just add

@InitBinder
public void initBinder(WebDataBinder binder) {
    binder.registerCustomEditor(String.class, new StringTrimmerEditor(true));
}

instructions here