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:

ValidationResult

Method Summary

Modifier and Type	Method	Description
static <T> Validator<T>	alwaysPass()	Returns a validator that passes any value.
ValidationResult	apply(T value, ValueContext context)	Validates the given value.
static <T> Validator<T>	from(SerializablePredicate<T> guard, ErrorMessageProvider errorMessageProvider)	Builds a validator out of a conditional function and an error message provider.
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.
static <T> Validator<T>	from(SerializablePredicate<T> guard, String errorMessage)	Builds a validator out of a conditional function and an error message.
static <T> Validator<T>	from(SerializablePredicate<T> guard, String errorMessage, ErrorLevel errorLevel)	Builds a validator out of a conditional function and an error message.

Methods inherited from interface java.util.function.BiFunction

andThen

Method Detail

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