porting 7.6-rc1 into 8

src/Umbraco.Core/StringUdi.cs

@@ -0,0 +1,73 @@
+using System;
+using System.ComponentModel;
+
+namespace Umbraco.Core
+{
+    /// <summary>
+    /// Represents a string-based entity identifier.
+    /// </summary>
+    [TypeConverter(typeof(UdiTypeConverter))]
+    public class StringUdi : Udi
+    {
+        /// <summary>
+        /// The string part of the identifier.
+        /// </summary>
+        public string Id { get; private set; }
+
+        /// <summary>
+        /// Initializes a new instance of the StringUdi class with an entity type and a string id.
+        /// </summary>
+        /// <param name="entityType">The entity type part of the udi.</param>
+        /// <param name="id">The string id part of the udi.</param>
+        public StringUdi(string entityType, string id)
+            : base(entityType, "umb://" + entityType + "/" + id)
+        {
+            Id = id;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the StringUdi class with a uri value.
+        /// </summary>
+        /// <param name="uriValue">The uri value of the udi.</param>
+        public StringUdi(Uri uriValue)
+            : base(uriValue)
+        {
+            Id = uriValue.AbsolutePath.TrimStart('/');
+        }
+
+        /// <summary>
+        /// Converts the string representation of an entity identifier into the equivalent StringUdi instance.
+        /// </summary>
+        /// <param name="s">The string to convert.</param>
+        /// <returns>A StringUdi instance that contains the value that was parsed.</returns>
+        public new static StringUdi Parse(string s)
+        {
+            var udi = Udi.Parse(s);
+            if (!(udi is StringUdi))
+                throw new FormatException("String \"" + s + "\" is not a string entity id.");
+            return (StringUdi)udi;
+        }
+
+        public static bool TryParse(string s, out StringUdi udi)
+        {
+            udi = null;
+            Udi tmp;
+            if (!TryParse(s, out tmp) || !(tmp is StringUdi)) return false;
+            udi = (StringUdi)tmp;
+            return true;
+        }
+
+        /// <inheritdoc/>
+        public override bool IsRoot
+        {
+            get { return Id == string.Empty; }
+        }
+
+        /// <inheritdoc/>
+        public StringUdi EnsureClosed()
+        {
+            base.EnsureNotRoot();
+            return this;
+        }
+    }
+}