Com.Meddlingwithfire.Common

Contains some convenient commonly needed classes in .NET projects.

Example Validation

Validation setup consists of three stages:

• Set up an input model
• Set up a validator
• Test the input model against the validator

1. Setting up an input model

Just a POCO. Doesn't require anything special.

public class ContactFormInputModel
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Birthdate { get; set; }
    public string EmailAddress { get; set; }
    public bool SignupForNewsletter { get; set; }
}

2. Set up your validator

The easiest way to go is to sub-class the Com.Meddlingwithfire.Common.Validation.BaseValidator class. This provides a virtual method for you to override void DoValidate(T input), defines a set of convenience methods for testing various data points (MustHaveContent, MustBeValidDate, etc.), and takes care of some basic plumbing to make the validation easier to consume.

public class ContactFormValidator : BaseValidator<ContactFormInputModel>
{
    override protected void DoValidate(ContactFormInputModel input)
    {
        MustHaveContent(input.FirstName, "FirstName", "First name");
        MustBeValidEmailAddress(input.EmailAddress, "EmailAddress", "Email address");
        MustBeValidDate(input.Birthdate, "Birthdate", "Birthdate");
    }
}

3. Test the input model against the validator

ContactFormInputModel input = new ContactFormInputModel()
{ 
    // FirstName is missing
    LastName = "O'neill",
    Birthdate = "10/35/1952", // Invalid date
    EmailAddress = "joneill@", // Invalid email address
    SignupForNewsletter = false
};
ContactFormValidator validator = new ContactFormValidator();
ValidationResultSet results = validator.Validate(input);
if (results.HasErrors)
{
  Console.WriteLine("Errors:");
  IEnumerable<string> messages = results.GetAllErrorMessages();
  foreach (string message in messages)
  {
    Console.WriteLine(message);
  }
}
else
{
  Console.WriteLine("No errors!");
}

The above setup will run and output the following console lines:

Errors:
First name is required
Email address must be a valid email address
Birthdate must be a valid date