Is there an easy way to turn empty Java/Spring form input into null strings?

Question

Is there an easy way to turn empty form input into null strings in java? I'm using spring mvc and SimpleJdbcInsert to insert the object 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!

edit - 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);  
        }  
    }  
}  

Two problems - first, no getAsText, so my form was getting populated with "null" strings! 2nd, 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

Set the default value for your optional fields to NULL - actually is it not NULL by default?

Parse your input string and then explicitly specify only populated columns with

 usingColumns

oh, and I'd advise to always sanitise your inputs...

Answer 2

Perhaps you can use a custom Binder

Answer 3

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