Model Warnings in ASP.NET MVC

Question

I\'m currently using the ModelStateDictionary in asp.net mvc to hold validation errors and pass then back to the user. Being able to check if the whole model is valid with Model

Answer 1

I used the solution from Simon Farrow as a starting point to make the warnings work with Kendo's datasource. By default you can return and show Data OR Errors but I wanted to return and show Data AND Warnings. So I've wrapped Kendo's DataSourceResult and added another extension method which returns the collected warnings.

// The wrapper
public class DataSourceResultWithWarnings: DataSourceResult
{
    public object Warnings { get; }

    public DataSourceResultWithWarnings(DataSourceResult dataSourceResult, IDictionary>> warnings)
    {
        this.AggregateResults = dataSourceResult.AggregateResults;
        this.Data = dataSourceResult.Data;
        this.Errors = dataSourceResult.Errors;
        this.Total = dataSourceResult.Total;
        Warnings = warnings;
    }
}

// The extension method
public static IDictionary>> GetWarnings(this ModelStateDictionary msd)
{
    var result = new Dictionary>>();

    for (var i = 0; i < msd.Values.Count; i++)
    {
        var wms = msd.Values.ElementAt(i) as WarningModelState;
        if (wms != null)
        {
            if (!result.ContainsKey(msd.Keys.ElementAt(i)))
            {
                result.Add(msd.Keys.ElementAt(i), new Dictionary>() { { "warnings", new List() } });
            }
            result[msd.Keys.ElementAt(i)]["warnings"].AddRange((from rec in wms.Warnings select rec.ErrorMessage));
        }
    }

    return result;
}

// How to use it in the controller action
var result = new DataSourceResultWithWarnings(files.Values.ToDataSourceResult(request, ModelState), ModelState.GetWarnings());
return Json(result, JsonRequestBehavior.AllowGet);