This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Framework 7.0.7!

`@InitBinder`

See equivalent in the Reactive stack

@Controller or @ControllerAdvice classes can have @InitBinder methods to initialize WebDataBinder instances that in turn can:

Bind request parameters to a model object.
Convert request values from string to object property types.
Format model object properties as strings when rendering HTML forms.

In an @Controller, DataBinder customizations apply locally within the controller, or even to a specific model attribute referenced by name through the annotation. In an @ControllerAdvice customizations can apply to all or a subset of controllers.

You can register PropertyEditor, Converter, and Formatter components in the DataBinder for type conversion. Alternatively, you can use the MVC config to register Converter and Formatter components in a globally shared FormattingConversionService.

@InitBinder methods can have many of the same arguments that @RequestMapping methods have, with the notable exception of @ModelAttribute. Typically, such methods have a WebDataBinder argument (for registrations) and a void return value, for example:

Java
Kotlin

@Controller
public class FormController {

	@InitBinder (1)
	public void initBinder(WebDataBinder binder) {
		SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
		dateFormat.setLenient(false);
		binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
	}

	// ...
}

1	Defining an `@InitBinder` method.

@Controller
class FormController {

	@InitBinder (1)
	fun initBinder(binder: WebDataBinder) {
		val dateFormat = SimpleDateFormat("yyyy-MM-dd")
		dateFormat.isLenient = false
		binder.registerCustomEditor(Date::class.java, CustomDateEditor(dateFormat, false))
	}

	// ...
}

1	Defining an `@InitBinder` method.

Alternatively, when you use a Formatter-based setup through a shared FormattingConversionService, you can re-use the same approach and register controller-specific Formatter implementations, as the following example shows:

Java
Kotlin

@Controller
public class FormController {

	@InitBinder (1)
	protected void initBinder(WebDataBinder binder) {
		binder.addCustomFormatter(new DateFormatter("yyyy-MM-dd"));
	}

	// ...
}

1	Defining an `@InitBinder` method on a custom formatter.

@Controller
class FormController {

	@InitBinder (1)
	protected fun initBinder(binder: WebDataBinder) {
		binder.addCustomFormatter(DateFormatter("yyyy-MM-dd"))
	}

	// ...
}

1	Defining an `@InitBinder` method on a custom formatter.

For more guidance on model design, please see Data Binding.