ann-initbinder.adoc

DataBinder

See equivalent in the Servlet 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 WebFlux config to register Converter and Formatter components in a globally shared FormattingConversionService.

Java

@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. Using the @InitBinder annotation.

Kotlin

@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. Using the @InitBinder annotation.

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

Java

@Controller
public class FormController {

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

	// ...
}

1. Adding a custom formatter (a DateFormatter, in this case).

Kotlin

@Controller
class FormController {

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

	// ...
}

1. Adding a custom formatter (a DateFormatter, in this case).

Model Design

See equivalent in the Servlet stack

partial$web/web-data-binding-model-design.adoc