How to pass in a list of generic objects into a method?

Question

My CheckModelValidation method (that tests a single model) tests out fine in my unit test just by passing in the class model UserInsertModel as an object but when I try to pass in a list of models to CheckModelListValidation in my unit test, it tells me it's an unknown method (because it doesn't like what I'm trying to pass in - which is a List<UserInsertModel>).

Is there a better way to do this using generics (which I've just recently gotten into)?

public class ValidationManager
{
    public static void CheckModelListValidation(List<object> model)
    {
        string errorMessages = "";
        int iCnt = 0;
        foreach (var u in model)
        {
            iCnt += 1;
            string itemErrors = ValidateModel(u);
            if (!string.IsNullOrEmpty(itemErrors))
            {
                errorMessages = string.Format("Item {0} errors: {1}", iCnt, itemErrors);
            }
        }
        if (!string.IsNullOrEmpty(errorMessages))
        {
            throw new Exception(errorMessages);
        }
    }

    public static void CheckModelValidation(object model)
    {
        string errorMessages = ValidateModel(model);
        if (!string.IsNullOrEmpty(errorMessages))
        {
            throw new Exception(errorMessages);
        }  
    }

    private static string ValidateModel(object model)
    {
        string errorMessages = "";
        List<ValidationResult> validationResults = new List<ValidationResult>();
        ValidationContext valContext = new ValidationContext(model, null, null);
        bool isValid = Validator.TryValidateObject(model, valContext, validationResults, true);
        if (!isValid)
        {
            errorMessages= string.Format("Errors: {0}", String.Join("; ", validationResults.Select(v => v.ErrorMessage).ToArray()));
        }
        return errorMessages;
    }
}

And here's my implementation:

UserInsertModel model = new UserInsertModel();
model.EmailAddress = "test";

List<UserInsertModel> models = new List<UserInsertModel>();
models.Add(model);
models.Add(model);

ValidationManager.CheckModelListValidation(models);

Reed Copsey · Accepted Answer · 2014-02-10 20:56:35Z

2

You can make your validation class generic:

public class ValidationManager<T>
{
     // Change methods to accept T instead of object
     public static void CheckModelListValidation(List<T> model)
     {

     //...

     public static void CheckModelValidation(T model)
     {
      // etc

edited Feb 10, 2014 at 20:56

answered Feb 10, 2014 at 20:49

Reed Copsey

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2 Comments

RichC Over a year ago

You should have seen the giant lightbulb that just went off in my head over how generics work just now with the whole class ValidationManager<T> thing. It finally "clicked" lol One question, though, should (or can) I change CheckModelValidation(object model) to CheckModelValidation(<T> model)? When it do, I get a ton of errors. I'm not sure my syntax is right.

Reed Copsey Over a year ago

@RichC Yeah, just (T model), not <T> :)

Ivo · Accepted Answer · 2014-02-10 20:52:00Z

2

Change the signature of the method to:

public static void CheckModelListValidation<T>(List<T> model)

answered Feb 10, 2014 at 20:52

Ivo

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