The FOD validation system provides comprehensive validators with fluent API chaining, localization support, and seamless integration with form components.
Use the fluent ValidatorExtensions.For<T>() API to chain validators together.
Fluent API Example
// Chain validators using fluent API
var validation = ValidatorExtensions
.For<string>()
.Required()
.Email()
.MinLength(5)
.MaxLength(100)
.ToValidationWithLabel();
// Use with FodTextField
<FodTextField Label="Email"
@bind-Value="@email"
Validation="@validation" />Complete reference of all built-in validators with live interactive examples.
RequiredValidator
EmailValidator
StringLengthValidator - Minimum Length
StringLengthValidator - Maximum Length
StringLengthValidator - Length Range
URLValidator
PhoneValidator
RegexValidator - Alphanumeric Only
CompareValidator
CustomValidator
// RequiredValidator
.Required()
// EmailValidator
.Email()
// StringLengthValidator
.MinLength(5)
.MaxLength(10)
.StringLength(minLength: 5, maxLength: 15)
// URLValidator
.Url()
// PhoneValidator
.Phone()
// RegexValidator
.Regex(pattern: @"^[a-zA-Z0-9]+$", errorMessage: "Only alphanumeric")
// CompareValidator
.Compare(_ => passwordValue, comparisonPropertyName: "Password")
// CustomValidator
.Custom((value, context) => int.TryParse(value, out var num) && num % 2 == 0,
errorMessage: "Must be an even number")User registration form demonstrating validation with multiple fields and error handling.
Current form values:
First Name: (empty)
Last Name: (empty)
Email: (empty)
Username: (empty)
Password: (empty)
Confirm Password: (empty)
Age: (empty)
Phone Number (Optional): (empty)
Website (Optional): (empty)
Bio: (empty)// Form validators with fluent API
_formEmailValidation = ValidatorExtensions.For<string>()
.Required()
.Email()
.MaxLength(100)
.ToValidationWithLabel();
_formUsernameValidation = ValidatorExtensions.For<string>()
.Required()
.MinLength(3)
.MaxLength(20)
.Regex(pattern: @"^[a-zA-Z0-9]+$",
errorMessage: "Username can only contain letters and numbers")
.ToValidationWithLabel();
// Custom age validation
_formAgeValidation = ValidatorExtensions.For<string>()
.Required()
.Custom((value, context) =>
{
if (int.TryParse(value, out var age))
return age >= 18 && age <= 120;
return false;
}, errorMessage: "Age must be between 18 and 120")
.ToValidationWithLabel();Specialized validators for Moldova-specific identification numbers and codes.
IDNP (Personal Identification Number)
IDNO (Organization Identification Number)
IDNX (Universal Identification Number)
IDNV (State Vehicle Identification Number)
Cadastral Code - Terrain Format
Cadastral Code - Construction Format
Cadastral Code - Isolated Room Format
CUATM (Territory Classification Code)
CAEM (Economic Activity Classifier)
Moldova Phone Number
// IDNP - Personal Identification Number
.Idnp()
// IDNO - Organization Identification Number
.Idno()
// IDNX - Universal (IDNP or IDNO)
.Idnx()
// IDNV - State Vehicle Identification Number
.Idnv()
// Cadastral Code
.CadastralCode()
// CUATM - Territory Classification
.Cuatm()
// CAEM - Economic Activity Classifier
.Caem()
// Moldova Phone Number
.MoldovaPhone()Guidelines for implementing accessible validation in your forms.
<FodTextField Label="Email" Required="true" Validation="@_emailValidation" />Validation system types and their descriptions.