Convert String to Type, where Type is a variable

Question

I am attempting to create a standard method to handle populating a view model based on stored values in a cookie, that are used as user defaults for search criteria.

I am having issues when it comes to converting the string cookie values to the property type so the view model can be updated appropriately. Getting the following error:

Invalid cast from 'System.String' to 'System.Reflection.RuntimePropertyInfo'.

Here is what I have:

public TViewModel GetUserSearchCriteriaDefaults<TViewModel>(TViewModel viewModel)
        where TViewModel : class
{
    Type type = viewModel.GetType();
    string className = viewModel.GetType().Name;
    PropertyInfo[] properties = type.GetProperties();

    if (Request.Cookies[className] != null)
    {
        string rawValue;

        foreach (PropertyInfo property in properties)
        {
            if (!String.IsNullOrEmpty(Request.Cookies[className][property.Name]))
            {
                rawValue = Server.HtmlEncode(Request.Cookies[className][property.Name]);
                Type propertyType = property.GetType();
                var convertedValue = Convert.ChangeType(rawValue, propertyType); <---- Error from this line
                property.SetValue(viewModel, convertedValue);
            }
        }
    }

    return viewModel;
}

I see that you're trying to make this super generic, but it would seem that this would only allow you to store a single instance of any class in the cookie. This may fit your needs at first glance but kinda defeats the purpose of being super generic imo. Why not just create a string to view model adapter for the classes that you need, then maybe use a factory to dig them out of your cookies? It would be more "intentional" (for lack of a better term) and less prone to ...weirdness? — Sinaesthetic
– Sinaesthetic, Commented Jul 17, 2013 at 15:31

Raphaël Althaus · Accepted Answer · 2013-07-17 15:19:50Z

12

change

Type propertyType = property.GetType();

to

Type propertyType = property.PropertyType;

Using GetType(), you get the type of property. And property is an instance of PropertyInfo.

answered Jul 17, 2013 at 15:19

Raphaël Althaus

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