At the moment, the best way to get a property alias based on a generated model is to use

var propertyType = ModelClassName.GetModelPropertyType(d => d.PropertyName);
var alias = propertyType.PropertyTypeAlias;

Getting the alias like this allows you to not depend on magic strings in many cases, for example when calling IContent.SetValue().

I've tried to come up with a general solution for this, so I first created a new method on each partial class that extends a generated model. Given that large solutions can contain many model classes however, I thought a more appropriate solution could be found.

After spending some time on this, I realised that any reusable code would have to be put in the base class that all generated models inherit from, which of course I couldn't extend.

In the process of reviewing the code for this on GitHub, I also realised that the GetModelPropertyType() method call is hitting the database, which in my opinion isn't ideal.

Does anyone have any suggestions about how this can be done in a better way?

I've thought about using Reflection to read the property attributes, but a more robust solution would be for the generated models to add one constant per property, for example:

public const string BodyTextPropertyAlias = "bodyText";

[ImplementPropertyType(BodyTextPropertyAlias)]
public IHtmlString BodyText
{
    get { return this.GetPropertyValue<IHtmlString>(BodyTextPropertyAlias); }
}

as they do now for the model class:

public new const string ModelTypeAlias = "documentTypeAlias";

which however seems like something that the ModelsBuilder would have to take care of.