Umbraco-CMS/src/Umbraco.Core/PropertyEditors/ValueConverters/TextStringValueConverter.cs

using System;
using System.Linq;
using Umbraco.Core.Models.PublishedContent;

namespace Umbraco.Core.PropertyEditors.ValueConverters
{
    [DefaultPropertyValueConverter]
    public class TextStringValueConverter : PropertyValueConverterBase
    {
        private static readonly string[] PropertyTypeAliases =
        {
            Constants.PropertyEditors.Aliases.TextBox,
            Constants.PropertyEditors.Aliases.TextArea
        };

        public override bool IsConverter(IPublishedPropertyType propertyType)
            => PropertyTypeAliases.Contains(propertyType.EditorAlias);

        public override Type GetPropertyValueType(IPublishedPropertyType propertyType)
            => typeof (string);

        public override PropertyCacheLevel GetPropertyCacheLevel(IPublishedPropertyType propertyType)
            => PropertyCacheLevel.Element;

        public override object ConvertSourceToIntermediate(IPublishedElement owner, IPublishedPropertyType propertyType, object source, bool preview)
        {
            // in xml a string is: string
            // in the database a string is: string
            // default value is: null
            return source;
        }

        public override object ConvertIntermediateToObject(IPublishedElement owner, IPublishedPropertyType propertyType, PropertyCacheLevel referenceCacheLevel, object inter, bool preview)
        {
            // source should come from ConvertSource and be a string (or null) already
            return inter ?? string.Empty;
        }

        public override object ConvertIntermediateToXPath(IPublishedElement owner, IPublishedPropertyType propertyType, PropertyCacheLevel referenceCacheLevel, object inter, bool preview)
        {
            // source should come from ConvertSource and be a string (or null) already
            return inter;
        }
    }
}