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com.vaadin.flow.data.binder.
Package com.vaadin.flow.data.binder

Interface Validator<T>

Type Parameters:

T - the type of the value to validate

All Superinterfaces:

BiFunction<T,ValueContext,ValidationResult>, Serializable

All Known Implementing Classes:

AbstractValidator, BeanValidator, BigDecimalRangeValidator, BigIntegerRangeValidator, ByteRangeValidator, DateRangeValidator, DateTimeRangeValidator, DoubleRangeValidator, EmailValidator, FloatRangeValidator, IntegerRangeValidator, LongRangeValidator, RangeValidator, RegexpValidator, ShortRangeValidator, StringLengthValidator

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface public interface Validator<T> extends BiFunction<T,ValueContext,ValidationResult>, Serializable

A functional interface for validating user input or other potentially invalid data. When a validator instance is applied to a value of the corresponding type, it returns a result signifying that the value either passed or failed the validation.

For instance, the following validator checks if a number is positive: 

 Validator<Integer> v = num -> {
     if (num >= 0)
         return ValidationResult.ok();
     else
         return ValidationResult.error("number must be positive");
 };

Since:

1.0.

Author:

Vaadin Ltd

See Also:

  • Method Details

    • apply

      ValidationResult apply(T value, ValueContext context)

      Validates the given value. Returns a ValidationResult instance representing the outcome of the validation.

      Specified by:

      apply in interface BiFunction<T,ValueContext,ValidationResult>

      Parameters:

      value - the input value to validate

      context - the value context for validation

      Returns:

      the validation result

    • alwaysPass

      static <T> Validator<T> alwaysPass()

      Returns a validator that passes any value.

      Type Parameters:

      T - the value type

      Returns:

      an always-passing validator

    • from

      static <T> Validator<T> from(SerializablePredicate<T> guard, String errorMessage)

      Builds a validator out of a conditional function and an error message. If the function returns true, the validator returns Result.ok(); if it returns false or throws an exception, ValidationResult.error(String) is returned with the given message and error level ErrorLevel.ERROR.

      For instance, the following validator checks if a number is between 0 and 10, inclusive: 

       Validator<Integer> v = Validator.from(num -> num >= 0 && num <= 10,
         "number must be between 0 and 10");

      Type Parameters:

      T - the value type

      Parameters:

      guard - the function used to validate, not null

      errorMessage - the message returned if validation fails, not null

      Returns:

      the new validator using the function

    • from

      static <T> Validator<T> from(SerializablePredicate<T> guard, String errorMessage, ErrorLevel errorLevel)

      Builds a validator out of a conditional function and an error message. If the function returns true, the validator returns Result.ok(); if it returns false or throws an exception, ValidationResult.error(String) is returned with the given message and error level.

      For instance, the following validator checks if a number is between 0 and 10, inclusive: 

       Validator<Integer> v = Validator.from(num -> num >= 0 && num <= 10,
         "number must be between 0 and 10", ErrorLevel.ERROR);

      Type Parameters:

      T - the value type

      Parameters:

      guard - the function used to validate, not null

      errorMessage - the message returned if validation fails, not null

      errorLevel - the error level for failures from this validator, not null

      Returns:

      the new validator using the function

    • from

      static <T> Validator<T> from(SerializablePredicate<T> guard, ErrorMessageProvider errorMessageProvider)

      Builds a validator out of a conditional function and an error message provider. If the function returns true, the validator returns Result.ok(); if it returns false or throws an exception, Result.error() is returned with the message from the provider.

      Type Parameters:

      T - the value type

      Parameters:

      guard - the function used to validate, not null

      errorMessageProvider - the provider to generate error messages, not null

      Returns:

      the new validator using the function

    • from

      static <T> Validator<T> from(SerializablePredicate<T> guard, ErrorMessageProvider errorMessageProvider, ErrorLevel errorLevel)

      Builds a validator out of a conditional function and an error message provider. If the function returns true, the validator returns Result.ok(); if it returns false or throws an exception, Result.error() is returned with the message from the provider.

      Type Parameters:

      T - the value type

      Parameters:

      guard - the function used to validate, not null

      errorMessageProvider - the provider to generate error messages, not null

      errorLevel - the error level for failures from this validator, not null

      Returns:

      the new validator using the function

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