GetVortoValue returns null in 1.7.0 version

[zd-dalibor]

After upgrading to 1.7.0 content.GetVortoValue("someAlias") or content.GetVortoValue<object>("someAlias") returns null, but content.GetVortoValue<string>("someAlias") working.

This content.GetVortoValue("someAlias") worked in 1.6.0.

[NikRimington]

Hi @dalibor983,

Do you have any more information on this? I'm getting an issue even when specifying a return type after upgrading my install to v 1.7.0 as well. This is running on an Umbraco 7.13.1 site.

Thanks

Nik

[zd-dalibor]

Hi @NikRimington,

I've tried to debug 1.7.0 version but there are no debugging symbols for this nuget package.

[mattbrailsford]

@dalibor983 you may need to pull the source down and compile it in debug to generate the PDBs and to set breakpoints into the codebase.

1.7.0 saw a big update to the internal API so it's possible something has changed.

[zd-dalibor]

@mattbrailsford I think I found the problem

https://github.com/umco/umbraco-vorto/blob/44b9af7bec24129d1a008a5f3d1f414fa8c67904/src/Our.Umbraco.Vorto/Extensions/IPublishedContentExtensions.cs#L102

For content.GetVortoValue("someAlias") type of T is object. In my case prop.Value is instance of VortoValue<string> so:

var vortoModel = prop.Value as VortoValue<T>; // casting VortoValue<string> to VortoValue<object>
// vortoModel is null

so private static T DoGetVortoValue<T>(this IPublishedContent content, string propertyAlias, string cultureName = null, recursive = false, T defaultValue = default(T)) will returns null because in my case recursive property is false.

We must find better way to cast prop.Value to VortoValue<T>.

[mattbrailsford]

I'm open to suggestions

[mattbrailsford]

Maybe we could add an implicit operator to VortoValue<T> to allow it to be cast as other types and it takes the generic arg and tries to cast it's generic arg type to that? Or maybe at minimum an implicit operator for VortoValue<object>

[mattbrailsford]

Maybe adding this to VortoValue<T> could work?

public static implicit operator VortoValue<object>(VortoValue<T> v)
{
    var newVortoValue = new VortoValue<object>() {
        Values = v.Values.ToDictionary(x => x.Key, x => x.Value as object)
            .Where(x => x.Value != null)
            .ToDictionary(x => x.Key, x => x.Value)
    };

    return newVortoValue.Values.Count > 0 ? newVortoValue : null;
}

[mattbrailsford]

Actually, this won't work. I think we might need a base class / interface that has an explicit casting method. You can then cast to the interface first to make sure it's a vorto value and then call the cast method to force it to the required type.

[mattbrailsford]

Potential fix here #117 if someone wants to try the nightly https://ci.appveyor.com/project/UMCO/umbraco-vorto/builds/22396168/artifacts

The PR has an annoying ammount of changes due to tabs and spaces, but the main change for this is here https://github.com/umco/umbraco-vorto/pull/117/files#diff-e3939f24b4a5c08135ae25b1a6faf5d5R102. I cast to IVortoValue first to make sure it's a vorto value, and then call a new CastToVortoValue<T>() method.

[zd-dalibor]

@mattbrailsford #117 this fixed the problem to me. It works now.

I tested the source code from wip/vorto-value-casting branch in my project.

[ronaldbarendse]

@mattbrailsford Looks like this should be fixed by using an interface with a covariant generic type parameter: https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/covariance-contravariance/creating-variant-generic-interfaces.

void Main()
{
    var stringValue = new TestValue<string>()
    {
        Value = "Test"
    };

    var objectValue = (stringValue as ITestValue<object>);
    if (objectValue != null)
    {
        // The value could be boxed to object, so return value
    }
    else
    {
        // No conversion exists, so return null
    }
}

public interface ITestValue<out T>
{
    T Value { get; }
}

public class TestValue<T> : ITestValue<T>
{
    public T Value { get; set; }
}