Implements: U4-3171 Create an interface for RelationService

src/Umbraco.Core/Models/IRelation.cs

@@ -0,0 +1,38 @@
+using System.Runtime.Serialization;
+using Umbraco.Core.Models.EntityBase;
+
+namespace Umbraco.Core.Models
+{
+    public interface IRelation : IAggregateRoot
+    {
+        /// <summary>
+        /// Gets or sets the Parent Id of the Relation (Source)
+        /// </summary>
+        [DataMember]
+        int ParentId { get; set; }
+
+        /// <summary>
+        /// Gets or sets the Child Id of the Relation (Destination)
+        /// </summary>
+        [DataMember]
+        int ChildId { get; set; }
+
+        /// <summary>
+        /// Gets or sets the <see cref="RelationType"/> for the Relation
+        /// </summary>
+        [DataMember]
+        IRelationType RelationType { get; set; }
+
+        /// <summary>
+        /// Gets or sets a comment for the Relation
+        /// </summary>
+        [DataMember]
+        string Comment { get; set; }
+
+        /// <summary>
+        /// Gets the Id of the <see cref="RelationType"/> that this Relation is based on.
+        /// </summary>
+        [IgnoreDataMember]
+        int RelationTypeId { get; }
+    }
+}