Decorator Reference

All built-in validation decorators live under Source/Pipes/Decorators/. Each is a Delphi RTTI attribute that annotates a DTO property. The TValidationPipe scans the RTTI of the DTO class at runtime and invokes the corresponding constraint.

Usage pattern

uses
  Nidus.Decorator.IsEmail,
  Nidus.Decorator.IsNotEmpty;

type
  TMyDto = class
  public
    [IsNotEmpty('Field is required')]
    property Name: string read FName write FName;

    [IsEmail('Must be a valid email')]
    property Email: string read FEmail write FEmail;
  end;

The msg parameter is the error message returned when validation fails.

Common / string validators

Attribute	Unit	Description
[IsNotEmpty(msg)]	Nidus.Decorator.IsNotEmpty	Value must not be empty or whitespace
[IsEmpty(msg)]	Nidus.Decorator.IsEmpty	Value must be empty
[IsDefined(msg)]	Nidus.Decorator.IsDefined	Value must not be nil / unassigned
[IsEquals(other, msg)]	Nidus.Decorator.IsEquals	Value must equal other
[IsIn(vals, msg)]	Nidus.Decorator.IsIn	Value must be in the allowed set
[IsAlpha(msg)]	Nidus.Decorator.IsAlpha	Letters only
[IsAlphaNumeric(msg)]	Nidus.Decorator.IsAlphaNumeric	Letters and digits only
[IsAscii(msg)]	Nidus.Decorator.IsAscii	ASCII characters only
[Contains(sub, msg)]	Nidus.Decorator.Contains	Must contain substring
[IsFullWidth(msg)]	Nidus.Decorator.IsFullWidth	Full-width characters
[IsHalfWidth(msg)]	Nidus.Decorator.IsHalfWidth	Half-width characters

Numeric validators

Attribute	Unit	Description
[IsInteger(msg)]	Nidus.Decorator.IsInteger	Must be an integer
[IsNumber(msg)]	Nidus.Decorator.IsNumber	Must be a number
[IsDivisibleBy(n, msg)]	Nidus.Decorator.IsDivisibleBy	Must be divisible by n
[IsByteLength(min, max, msg)]	Nidus.Decorator.IsByteLength	Byte length in range

Type validators

Attribute	Unit	Description
[IsBoolean(msg)]	Nidus.Decorator.IsBoolean	Must be a boolean
[IsBooleanString(msg)]	Nidus.Decorator.IsBooleanString	Must be "true" / "false"
[IsEnum(TEnum, msg)]	Nidus.Decorator.IsEnum	Must be a valid enum value
[IsInstance(TClass, msg)]	Nidus.Decorator.IsInstance	Must be an instance of TClass
[IsAllow(vals, msg)]	Nidus.Decorator.IsAllow	Must be in the allowed set

Format validators

Attribute	Unit	Description
[IsEmail(msg)]	Nidus.Decorator.IsEmail	RFC 5322 email
[IsUUID(msg)]	Nidus.Decorator.IsUUID	UUID format
[IsIP(msg)]	Nidus.Decorator.IsIP	IPv4 or IPv6
[IsURL(msg)]	Nidus.Decorator.IsURL	URL format
[IsISO8601(msg)]	Nidus.Decorator.IsISO8601	ISO 8601 date-time
[IsDate(msg)]	Nidus.Decorator.IsDate	Date value
[IsDateString(msg)]	Nidus.Decorator.IsDateString	Date string
[IsHexColor(msg)]	Nidus.Decorator.IsHexColor	Hex color (#RRGGBB)
[IsHexadecimal(msg)]	Nidus.Decorator.IsHexadecimal	Hexadecimal string
[IsHsl(msg)]	Nidus.Decorator.IsHsl	HSL color
[IsCurrency(msg)]	Nidus.Decorator.IsCurrency	Currency format
[IsDataURI(msg)]	Nidus.Decorator.IsDataURI	Data URI
[IsGqdn(msg)]	Nidus.Decorator.IsGqdn	Fully qualified domain name

Financial / identity

Attribute	Unit	Description
[IsCreditCard(msg)]	Nidus.Decorator.IsCreditCard	Credit card number (Luhn)
[IsIban(msg)]	Nidus.Decorator.IsIban	IBAN
[IsBic(msg)]	Nidus.Decorator.IsBic	BIC/SWIFT code
[IsISO4217CurrencyCode(msg)]	Nidus.Decorator.IsISO4217CurrencyCode	ISO 4217 currency
[IsISO31661Alpha2(msg)]	Nidus.Decorator.IsISO31661Alpha2	ISO 3166-1 alpha-2 country
[IsISO31661Alpha3(msg)]	Nidus.Decorator.IsISO31661Alpha3	ISO 3166-1 alpha-3 country
[IsIdentityCard(msg)]	Nidus.Decorator.IsIdentityCard	Identity card number
[IsIsin(msg)]	Nidus.Decorator.IsIsin	ISIN securities code
[IsIsbn(msg)]	Nidus.Decorator.IsIsbn	ISBN
[IsEAN(msg)]	Nidus.Decorator.IsEAN	EAN barcode
[IsIson(msg)]	Nidus.Decorator.IsIson	ISON

Encoding / crypto

Attribute	Unit	Description
[IsBase64(msg)]	Nidus.Decorator.IsBase64	Base64
[IsBase32(msg)]	Nidus.Decorator.IsBase32	Base32
[IsBase58(msg)]	Nidus.Decorator.IsBase58	Base58
[IsBase(n, msg)]	Nidus.Decorator.IsBase	Base-N encoding
[IsHash(alg, msg)]	Nidus.Decorator.IsHash	Hash string
[IsBTCAddress(msg)]	Nidus.Decorator.IsBTCAddress	Bitcoin address
[IsEthereumAddress(msg)]	Nidus.Decorator.IsEethereumAddress	Ethereum address
[IsFirebasePushId(msg)]	Nidus.Decorator.IsFirebasePushId	Firebase Push ID

Array validators

Attribute	Unit	Description
[IsArray(msg)]	Nidus.Decorator.IsArray	Must be an array
[IsArrayNotEmpty(msg)]	Nidus.Decorator.IsArrayNotEmpty	Array must not be empty
[IsArrayUnique(msg)]	Nidus.Decorator.IsArrayUnique	All elements must be unique
[IsArrayMinSize(n, msg)]	Nidus.Decorator.IsArrayMinSize	Minimum element count
[IsArrayMaxSize(n, msg)]	Nidus.Decorator.IsArrayMaxSize	Maximum element count
[ArrayContains(val, msg)]	Nidus.Decorator.ArrayContains	Array must contain val
[ArrayNotContains(val, msg)]	Nidus.Decorator.ArrayNotContains	Array must not contain val

Password strength

Attribute	Unit	Description
[IsStrongPassword(msg)]	Nidus.Decorator.IsStrongPassword	Must meet strong-password criteria

Strong-password criteria

The validation logic in Nidus.Validation.IsStrongPassword is currently a stub. Until the implementation is complete, the decorator registers the tag but performs no actual check.

Custom constraints

Implement IValidatorConstraint from Nidus.Validation.Interfaces to create your own constraint, then wrap it in a custom RTTI attribute. Extend TValidatorConstraint (from Nidus.Validator.Constraint) to get the interface wired automatically and override only Validate:

type
  TMyConstraint = class(TValidatorConstraint)
  public
    function Validate(const Value: TValue;
      const Args: IValidationArguments): TResultValidation; override;
  end;

function TMyConstraint.Validate(const Value: TValue;
  const Args: IValidationArguments): TResultValidation;
begin
  if {your condition on Value} then
    Result.Success(True)
  else
    Result.Failure(IfThen(Args.Message = '', 'Validation failed', Args.Message));
end;

type
  MyRuleAttribute = class(IsAttribute)
  public
    constructor Create(const AMessage: string = ''); override;
    function Validation: TValidation; override;
  end;

constructor MyRuleAttribute.Create(const AMessage: string);
begin
  inherited Create(AMessage);
  FTagName := 'MyRule';
end;

function MyRuleAttribute.Validation: TValidation;
begin
  Result := TMyConstraint;
end;