Myce.FluentValidator 1.2.4

MYCE.FluentValidator

MYCE (Makes Your Coding Easier) FluentValidator is a fluent validation library designed to simplify entity validation in .NET applications.

Supports net6.0, net7.0, net8.0, net9.0, and netstandard2.0.

Installation

Package Manager Console:

Install-Package Myce.FluentValidator

Features

• FluentValidator: Fluent validation class for entities
• ValidatorBuilder: Orchestrates multiple validations in a single process
• High Performance: Optimized with typed value access to avoid boxing/unboxing.
• Reusable Templates: Define rules once and apply them to multiple DTOs.
• External Validation: Validate standalone variables or external states with RuleForValue.

Usage

1. Create your Entity

public class Person
{
   public string Name { get; set; }
   public int Age { get; set; }
   public string Email { get; set; }
   public string Code { get; set; }
}

2. Define Validation Rules

Use the FluentValidator to define rules for your entity properties.

var person = new Person { Name = "John Doe", Age = 30, Email = "john.doe@example.com", Code = "A123" };

var validator = new FluentValidator<Person>();
    .RuleFor(x => x.Name)
        .IsRequired()
        .MinLength(3)
        .MaxLength(50)
    .RuleFor(x => x.Age)
        .IsGreaterThanOrEqualTo(18)
        .IsLessThanOrEqualTo(100)
    .RuleFor(x => x.Email)
        .IsRequired()
        .IsValidEmailAddress()
    .RuleFor(x => x.Code)
        .ExactNumberOfCharacters(4)
        .ContainsOnlyNumber();

var result = validator.Validate(person);

if (validator.Messages.Any())
{
    foreach (var message in validator.Messages)
    {
        Console.WriteLine(message.Text);
    }
}

3. Reusable Templates (DRY Principle)

You can define validation logic for common fields (like Email) and reuse them across different classes.

public static class SharedRules 
{
    public static void NameTemplate<T>(RuleBuilder<T, string> rb) where T : class
        => rb.IsRequired().MinLength(3).MaxLength(100);
}

// In your validator:
validator.RuleFor(x => x.FirstName).ApplyTemplate(SharedRules.NameTemplate);
validator.RuleFor(x => x.LastName).ApplyTemplate(SharedRules.NameTemplate);

4. External Value Validation

Use RuleForValue to validate data that isn't a property of your main entity, such as checking if a record already exists in the database.

bool emailAlreadyExists = service.CheckEmail(request.Email);

var validator = new FluentValidator<Person>()
    .RuleForValue(emailAlreadyExists, "Email Uniqueness")
    .IsFalse(new ErrorMessage("This email is already taken"));

Supported Validators

Core validators available: | Validator | Description | | :--- | :--- | | Custom | Allows you to define a custom validation function. | | IsNull |Validates if the property value is null. | | IsNotNull |Validates if the property value is not null. | | IsRequired | Validates that the property is not null or empty. | | IsRequiredIf | Validates that the property is required if a condition is true. | | IsTrue | Validates that the boolean attribute is true.| | IsFalse | Validates that the boolean attribute is false.|

Collection validators: | Validator | Description | | :--- | :--- | | IsEmpty | Validates that the collection is empty (contains no items). | | IsIn | Validates that the attribute value is present within a sequence of allowed valeus. | | HasItems | Validates that the collection is not empty and has at least one item. | | MaxNumberOfItems | Validates that the collection does not exceed a maximum number of items. |

Comparison validators: | Validator | Description | | :--- | :--- | | IsEqualTo | Validates equality to a specific value. | | IsNotEqualTo | Validates if the property value is not equal to a fixed value. |

Numeric validators: | Validator | Description | | :--- | :--- | | IsBetween | Validates that the value is between two specified values. | | IsGreaterThan | Validates that the value is greater than a specified value. | | IsGreaterThanOrEqualTo | Validates that the value is greater than or equal to a specified value. | | IsLessThan | Validates that the value is less than a specified value. | | IsLessThanOrEqualTo | Validates that the value is less than or equal to a specified value. | | IsPositive | Validates that the integer value is positive (greater than zero). | | IsNegative | Validates that the integer value is negative (less than zero). |

String validators: | Validator | Description | | :--- | :--- | | Contains | Validates that the string contains a specific substring. | | ContainsOnlyNumber | Validates that a string contains only numeric characters. | | ExactNumberOfCharacters | Validates that a string has an exact length. | | ExactNumberOfCharactersIf | Validates exact length if a condition is true. | | IsValidDate | Validates that a string can be parsed as a valid date. | | IsValidEmailAddress | Validates that a string is a valid email format. | | MaxLength | Validates the maximum length of a string. | | MaxLengthIf | Validates maximum length if a condition is true. | | MinLength | Validates the minimum length of a string. | | MinLengthIf | Validates minimum length if a condition is true. |

Notes

Version 1.2.4

• Add Custom validator to allow users to define their own validation logic with a custom function.

Version 1.2.3

• Add extension methods to validate collection and enumerable attributes.
• Added IsPositive and IsNegative validation rule for all numeric types (int, double, decimal) including nullable support.

Version 1.2.2

• Added IsBetween validation rule for all numeric types (int, double, decimal) including nullable support-
• Fixed fluent chaining for RuleForValue, allowing multiple external value validations in a single statement.

Version 1.2.1

• Internal engine updated to use GetAttributeValue<T> to eliminate boxing of primitive types and improve performance.

Version 1.2.0

• Added RuleForValue for external variable validation and ApplyTemplate for rule reuse.

Version 1.1.1

• Addedd new validators: IsNotNull, and IsNull.

Version 1.1.0

• Introduces multi-targeting support (net6.0, net7.0, net8.0, net9.0, and netstandard2.0) and full nullability support.

Version 1.0.0

• The initial stable release of Myce.FluentValidator, providing basic validation capabilities for .NET applications.

Dependencies

• Myce.Extensions
• Myce.Response

Contributions

Contributions are welcome! If you have a validation method you think is useful and can make life easier for other developers, please create a Pull Request and submit it. Attention: All submitted methods must include a unit test.

Developed by Fernando Prass