Using InitBinder with command objects

Question

I have a command object that represents a form object submitted. If a value from a form input field is blank, I want it to be null in the command object.

I read a different SO question that showed to use the InitBinder

I gave that a shot, but the initBinder method is never called.

My controller

package com.example;

import org.springframework.beans.propertyeditors.StringTrimmerEditor;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import com.example.MyDTO;

@Controller
public class MyControllerImpl implements MyController {

    @InitBinder("myControllerImpl")
    public void initBinder(WebDataBinder binder) {
        System.out.println("init binder");
        binder.registerCustomEditor(String.class, new StringTrimmerEditor(true));
    }

    @Override
    public String someAction( MyDTO someDTO ) {

        System.out.println(someDTO);

        // Do something with DTO. I want blank values to be null here

        return "somePage;
    }

}

DTO

package com.example;

public class MyDTO {

    private String name;

    public String getName() {

        return name;
    }

    public String setName() {

        return name;
    }

}

I also tried adding the class name to the InitBinder annotation

@InitBinder("myControllerImpl")

but it did not work.

What am I missing to get the init binder to be called?

I'm using Java 6 and Spring 3

score 1 · Answer 1 · answered May 11 '18 at 17:56

1

You need to add @ControllerAdvice to controller class.

answered May 11 '18 at 17:56

Antoniossss

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Missed that. Unfortunately, we're a bit outdated and using Spring 3.1.1 Not sure if I can upgrade to 3.2, most likely not. So this way probably won't work. – Spark323 May 11 '18 at 18:00
Should work. https://docs.spring.io/spring/docs/3.1.1.RELEASE/spring-framework-reference/htmlsingle/spring-framework-reference.html#portlet-ann-initbinder – Antoniossss May 11 '18 at 18:03
I have the InitBinder annotation, but it looks like @ControllerAdvice annotation wasn't added till 3.2 – Spark323 May 11 '18 at 18:08
@eric as I wrote, docs says it should work as it is, dunno what is happening on your side – Antoniossss May 11 '18 at 18:08
Looks like it is my interface causing the issue. When I removed the interface and added all of the @RequestMappings from the interface to the Impl, it worked. Not really sure why, but it's a starting place. – Spark323 May 11 '18 at 18:58

score 1 · Answer 2 · answered May 11 '18 at 19:10

The issue is that I'm using an interface on my controller. The implementation is proxied by Spring AOP. To get this to work, I had to add the following method on the interface:

@InitBinder
void initBinder(WebDataBinder binder);

Then in the implementation I have

@Override
public void initBinder(WebDataBinder binder) {
    System.out.println("init binder!");
    binder.registerCustomEditor(String.class, new StringTrimmerEditor(true));
}

Using InitBinder with command objects

2 Answers2