Package org.kiwiproject.validation

Annotation Interface Required

@Documented @Constraint(validatedBy={}) @Target({METHOD,FIELD,ANNOTATION_TYPE,CONSTRUCTOR,PARAMETER,TYPE_USE}) @Retention(RUNTIME) public @interface Required
Ensures that a value is provided (i.e. not null). Null values are always considered invalid. You can refine the behavior by allowing blank or empty Strings, collections, maps, or other types of object to be considered valid.

For CharSequence objects (e.g. regular String objects), use allowBlank to allow empty or whitespace-only Strings. It does not make sense to set allowEmpty to true but leave allowBlank as false, so in general when annotating CharSequence objects, setting allowBlank to true is preferred, though it is also correct to set both allowBlank and allowEmpty to true.

For Collection and Map objects, allowBlank has no effect, but allowEmpty will cause empty collections and maps to be considered valid.

For any other type of object, only allowEmpty has any effect. If you have a custom object that has a public method named isEmpty that has no arguments and returns boolean, this validator will attempt to invoke that method reflectively and use its return value to determine whether the object is empty or not.

  • Optional Element Summary

    Optional Elements
    Modifier and Type
    Optional Element
    Description
    boolean
    allowBlank
    Whether to allow an object that is a CharSequence to be blank, using StringUtils.isBlank(CharSequence) to perform the check.
    boolean
    allowEmpty
    Whether to allow an object to be "empty".
    Class<?>[]
    groups
     
    String
    message
     
    Class<? extends jakarta.validation.Payload>[]
    payload
     

  • Element Details

    • message

      String message
      Default:
      "{org.kiwiproject.validation.Required.message}"

    • groups

      Class<?>[] groups
      Default:
      {}

    • payload

      Class<? extends jakarta.validation.Payload>[] payload
      Default:
      {}

    • allowBlank

      boolean allowBlank
      Whether to allow an object that is a CharSequence to be blank, using StringUtils.isBlank(CharSequence) to perform the check.

      This only applies to CharSequence objects. All other (non-null) objects are always considered as not blank.

      Returns:
      true to allow a CharSequence to be blank, false to consider blank CharSequence as invalid
      Default:
      false

    • allowEmpty

      boolean allowEmpty
      Whether to allow an object to be "empty". For String values, just checks the value itself. For anything else, attempts to find and call an isEmpty() method which allow this annotation to work on other types of objects, for example on Collection objects.
      Returns:
      true to allow an object to be empty, false otherwise
      Default:
      false