Cymen Vig

Software Craftsman

Yet another round on the ModelState PercentComplete() extension

So there were a few issues with the previous version – at least when I wanted to extend it for some custom calculations so here is yet another version:

        public static int PercentComplete(this ModelStateDictionary modelStateDictionary, int? ScalePercentWithValueAsZero = null, int? MaxValue = 100)
        {
            int totalItems = 0;
            int validItems = 0;
            int percentComplete = 0;

            if (MaxValue.HasValue && (MaxValue.Value < 0 || MaxValue.Value > 100))
                throw new ArgumentOutOfRangeException("MaxValue must between 0 and 100!");

            if (modelStateDictionary.IsValid)
            {
                percentComplete = MaxValue.Value;
            }
            else
            {
                foreach (var item in modelStateDictionary)
                {
                    totalItems++;
                    if (item.Value.Errors.Count == 0)
                        validItems++;
                }

                if (totalItems > 0)
                    percentComplete = (100 * validItems) / totalItems;

                if (ScalePercentWithValueAsZero.HasValue)
                {
                    if (ScalePercentWithValueAsZero.Value >= percentComplete)
                    {
                        percentComplete = 0;
                    }
                    else
                    {
                        percentComplete = Convert.ToInt32(Math.Ceiling((double)(percentComplete - ScalePercentWithValueAsZero.Value) / (100 - ScalePercentWithValueAsZero.Value) * 100));
                    }
                }

                if (MaxValue.HasValue)
                {
                    percentComplete = percentComplete * MaxValue.Value / 100;
                }
            }

            return percentComplete;
        }

And if a model has a particularly complicated percentage complete calculation in which one needs to manually check some things and add to the total that can be done:

        public int CustomPercentComplete(Func<int?, int?, int> PercentComplete)
        {
            // scale percent complete 50-100% as 0-100%
            int basePercentAsZero = 50;

            // actually, scale 50-100% as 0-91%
            int max = 91;            

            // call default PercentComplete
            int percentComplete = PercentComplete(basePercentAsZero, max);

            // implement here your custom percente complete for the remaining 9%

            return percentComplete;
        }

An example of calling the custom percentage complete calculator on your model:

        myModelInstance.CustomPercentComplete(ModelState.PercentComplete);

And if you need to call either calculator but your controller action doesn’t bind to an instance of the model you need to calculate the percentage on, you can add a method in your controller like this one (hopefully there is a better way – let me know if you know of one):

        // Work around for getting percentage complete when in another action where the model is not the application
        // like so:
        // int percentComplete = MyPercentComplete(application);
        private int MyPercentComplete(MyApplication application)
        {
            return Convert.ToInt32(MyPercentCompleteAction(application).Content);
        }

        // Work around for getting percentage complete when in another action where the model is not the application
        // like so:
        // int percentComplete = Convert.ToInt32(MyPercentComplete(application).Content);
        private ContentResult MyPercentCompleteAction(MyApplication application)
        {
            return Content(application.CustomPercentComplete(ModelState.PercentComplete).ToString());
        }