RequiredEither - Conditional Validation Attribute using MVC / Web API

This topic illustrates how to extend ValidationAttribute to enforce customized validation of checking if either of the field's value is provided or not.

Scenario: Contact.Phone or Contact.Email value should be required.

We can achieve this by following below steps, and the illustration is developed using MVC 5, Web API 2, EF 6 and Moq

As a first step, Create a new class with name "RequiredEitherValidator" (preferably in a common location of the solution ie. either in Model or a Common project, as applied) and copy below code:

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
public class RequriedEitherValidator: ValidationAttribute
{

private string[] PropertyList { get; set; }

public RequriedEitherValidator(params string[] propertyList)

{

this.PropertyList = propertyList;

}

public override object TypeId

{

get { return this; }

}

public override bool IsValid(object value)

{

PropertyInfo propertyInfo;
foreach (string propertyName in PropertyList)
{
propertyInfo = value.GetType().GetProperty(propertyName);
if (propertyInfo != null && propertyInfo.GetValue(value, null) != null)
{
return true;
}
}
return false;

}

}

We need to create or make changes to Model(s) and Controller(s) as below to implement the created custom validation.

POCO / Model: Create or Modify Contact class to apply the custom validation on Phone and Email properties as below to define either of the field value is required.

[RequriedEitherValidator("Email", "Phone", ErrorMessage = "Either Email or Phone Data is Required")]
public class Contact
{

[Display(Name="First Name")]

[StringLength(50, ErrorMessage = "First Name cannot Exceed 50 Character length")]

[Required(ErrorMessage = "First Name is Required")]

public string FirstName {get; set; }

[Display(Name="Last Name")]

[StringLength(50, ErrorMessage = "Last Name cannot Exceed 50 Character length")]

[Required(ErrorMessage = "Last Name is Required")]

public string LastName { get; set; }

[StringLength(150)]

[RegularExpression("^[a-zA-Z0-9_\\.-]+@([a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,6}$", ErrorMessage = "Invalid Email address")]

public string Email { get; set; }

[RegularExpression(@"^([0-9]{10})$", ErrorMessage = "Invalid Phone Number")]

public string Phone { get; set; }

}

Controller: The controller for Contact entity with a POST method will look like below.

public class ContactController : ApiController
{

[AcceptVerbs("GET", "POST")]

[HttpPost]

[ActionName("CreateContact")]

public bool CreateContact([FromBody]Contact contact)

{

try
{
var isAdded = _contactRepository.CreateContact(contact);
return isAdded;
}
catch (Exception e)
{
throw e;
}

}

}

Testing: Below TestMethods will help testing the post method to check for the expected validation error:

[TestMethod]
public void FailedPhoneOrEmailDetailsTest()
{

Contact contact = new Contact { FirstName = "TestFirstName", LastName = "TestLastName", Phone = null, Email = null };

var validationResult = Validator.TryValidateObject(_Contacts, _ContactsContext, _validationResults, validateAllProperties: true);

Assert.IsFalse(validationResult);

Assert.AreEqual(1, _validationResults.Count);

Assert.AreEqual("Either Email or Phone Data is Required", _validationResults[0].ErrorMessage);

}

}

With this I am concluding the illustration. Feel free to share your feedback.

Happy Programming !!!