adding-support-for-new-properties.md

Adding support for additional property types

When the client editor model and the backing datatypes don't match up, this library tries to resolve an ILinkDataValueWriter for backing -> editor data conversion and ILinkDataAttributeConverter for editor -> backing data conversion. The first step is to register a value writer to get the property to show up in edit mode. Secondly if the property doesn't persist between page loads an attribute converter is probably needed too.

Implement and register an ILinkDataValueWriter

For reference this is the code that makes date pickers display correctly as System.Text.Json is used for from Optimizely to Dojo widget data transfer.

public class DateTimeValueWriter : ILinkDataValueWriter
{
    public bool CanWrite(Type type)
    {
        if (typeof(DateTime).IsAssignableFrom(type))
            return true;

        if (typeof(DateTime?).IsAssignableFrom(type))
            return true;

        return false;
    }

    public void Write(Utf8JsonWriter writer, object value)
    {
        var dateValue = (DateTime)value;
        writer.WriteStringValue(dateValue);
    }
}

Also register it for dependency injection in Startup.

services.TryAddEnumerable(ServiceDescriptor.Singleton<ILinkDataValueWriter, DateTimeValueWriter>());

Implement and register an ILinkDataAttributeConverter

This is the code that handles conversions of IConvertible datatypes from Dojo Widget to Optimizely.

public class ConvertibleAttributeConverter : ILinkDataAttibuteConverter
{
    public bool CanConvert(Type type)
    {
        return typeof(IConvertible).IsAssignableFrom(type);
    }

    public string? Convert(object value)
    {
        if (value is null)
            return null;

        return System.Convert.ToString((IConvertible)value, CultureInfo.InvariantCulture);
    }
}

Going beyond

More information about handling properties by overriding built in services to come.