DataBinder
@Controller
or @ControllerAdvice
classes can have @InitBinder
methods, to
initialize instances of WebDataBinder
. Those, in turn, are used to:
-
Bind request parameters (that is, form data or query) to a model object.
-
Convert
String
-based request values (such as request parameters, path variables, headers, cookies, and others) to the target type of controller method arguments. -
Format model object values as
String
values when rendering HTML forms.
@InitBinder
methods can register controller-specific java.beans.PropertyEditor
or
Spring Converter
and Formatter
components. In addition, you can use the
WebFlux Java configuration to register Converter
and
Formatter
types in a globally shared FormattingConversionService
.
@InitBinder
methods support many of the same arguments that @RequestMapping
methods
do, except for @ModelAttribute
(command object) arguments. Typically, they are declared
with a WebDataBinder
argument, for registrations, and a void
return value.
The following example uses the @InitBinder
annotation:
-
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 | Using the @InitBinder annotation. |
@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
-
Kotlin
@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). |
@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). |