使用C＃，如何将return语句注入方法？

Question

Thanks for looking, I realize the question is a bit odd. Here is what I am hoping to accomplish:

What I have

I am using System.ComponentModel.DataAnnotations to validate a model that has been posted from a web page. I have already partially abstracted the necessary code into a shared method:

public static string Create_Widget(WidgetModel postedWidget)
        {
            //Validate the model
            var errors = HelperMethods.Validate(postedWidget);
            if (!string.IsNullOrEmpty(errors))
            {
                return errors;
            }

            //Do other stuff

        }

And the helper method:

 public static string Validate<T>(T entity)
        {
            var context = new ValidationContext(entity, serviceProvider: null, items: null);
            var results = new List<ValidationResult>();
            Validator.TryValidateObject(entity, context, results);

            return string.Join(",", results.Select(s => s.ErrorMessage));
        }

What I would like to have

What I really want to do is just have an extension method to validate my model with out adding an if statement beneath it for the conditional return:

public static string Create_Widget(WidgetModel postedWidget)
            {
                //Validate the model
                postedWidget.Validate(); //Automatically returns error string if errors.

                //Do other stuff

            }

Is this possible?

Answer 1

Thanks to the help from the comments above, I produced the following code which does exactly as I wanted:

The Extension Method:

public static void Validate<T>(this T entity)
        {
            var errors = new List<ValidationResult>();
            var result = "";

            try
            {
                var context = new ValidationContext(entity, null, null);
                Validator.TryValidateObject(entity, context, errors, true);
                result = (errors.Any()) ? string.Join(",", errors.Select(s => s.ErrorMessage)) : "";
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }

            if (!string.IsNullOrEmpty(result))
            {
                throw new Exception(result);
            }
        }

Usage

Assuming you have a valid model with data validation annotations, all you need is this:

widgetModel.Validate();

If one or more properties within your model don't clear validation, a comma delimited list of errors is returned. In my case, I am using AngularJS in the view so I can use .error() to catch failed api calls and use the list of errors in the view.