Model Validation

A NuGet Package to aid with validating Models through the use of Attributes.

Use

The Model

Any model or class that wants to be validatable should inherit from ValidatableObject. This adds the Validate() method to the class, which automatically validates the class according to the attributes assigned to its properties.

Attributes

The base attribute is ValidatablePropertyAttribute which defines its own Validate() method to validate a property based on a single rule. This project defines several attributes that inherit from ValidatablePropertyAttribute which can be used.

• MaximumLength Attribute

  Ensures that the property does not exceed the specified maximum length

• MinimumLength Attribute

  Ensures that the property exceeds the specified minimum length

• ContainsCharacter Attribute

  Ensures that the property contains the specified character. (Useful for checking that an email has an '@' symbol)

• DoesNotContainCharacter Attribute

  Ensures that the property does not contain the specified container. (Useful for checking that a property has no spaces or ' ')

• PropertyValueMatch Attribute

  Ensures that the property's value matches with the value of the other specified property (Useful for checking that passwords match - Password & ConfirmPassword properties have to match)

Custom Attributes

Any class can extend from the base ValidatablePropertyAttribute and define custom validation attributes. When applied on a ValidatableObject, no additional work needs to be done to ensure that the Attributes's Validation Rules are called when the ValidatableObject's Validate() method is called.

The Error Messages can also be overridden by specifying them in the attribute constructor.

Example Model

using ModelValidation;

public class TestModel : ValidatableObject
{
    [MinimumLength(2)]
    [MaximumLength(64)]
    public string UserName { get; set; }

    [ContainsCharacter('@')]
    [DoesNotContainCharacter(' ')]
    [MinimumLength(5)]
    [MaximumLength(254)]
    public string Email { get; set; }

    [MinimumLength(8)]
    [MaximumLength(64)]
    public string Password { get; set; }

    [PropertyValueMatch(nameof(Password), ErrorMessage = "Passwords do not match")]
    public string ConfirmPassword { get; set; }
}

Calling TestModel.Validate() validates the model and stores any error messages into the Errors property, which is a List<string>.