Adding base model U4-921 and creating new branch.

src/Umbraco.Core/Models/EntityBase/Entity.cs

@@ -0,0 +1,221 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Serialization;
+
+namespace Umbraco.Core.Models.EntityBase
+{
+    /// <summary>
+    /// Base Abstract Entity
+    /// </summary>
+    [Serializable]
+    [DataContract(IsReference = true)]
+    public abstract class Entity : IEntity
+    {
+        private bool _hasIdentity;
+        private int? _hash;
+        private int _id;
+        private Guid _key;
+
+        /// <summary>
+        /// Integer Id
+        /// </summary>
+        [DataMember]
+        public int Id
+        {
+            get
+            {
+                return _id;
+            }
+            set
+            {
+                _id = value;
+                HasIdentity = true;
+            }
+        }
+
+        /// <summary>
+        /// Guid based Id
+        /// </summary>
+        /// <remarks>The key is currectly used to store the Unique Id from the 
+        /// umbracoNode table, which many of the entities are based on.</remarks>
+        [DataMember]
+        public Guid Key
+        {
+            get
+            {
+                if (_key == Guid.Empty)
+                    return Id.ToGuid();
+
+                return _key;
+            }
+            set { _key = value; }
+        }
+
+        /// <summary>
+        /// Gets or sets the Created Date
+        /// </summary>
+        [DataMember]
+        public DateTime CreatedDate { get; set; }
+
+        /// <summary>
+        /// Gets or sets the Modified Date
+        /// </summary>
+        [DataMember]
+        public DateTime ModifiedDate { get; set; }
+
+        /// <summary>
+        /// Property changed event
+        /// </summary>
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        /// <summary>
+        /// Method to call on a property setter.
+        /// </summary>
+        /// <param name="propertyInfo">The property info.</param>
+        protected virtual void OnPropertyChanged(PropertyInfo propertyInfo)
+        {
+            _propertyChangedInfo[propertyInfo.Name] = true;
+
+            if (PropertyChanged != null)
+            {
+                PropertyChanged(this, new PropertyChangedEventArgs(propertyInfo.Name));
+            }
+        }
+
+        /// <summary>
+        /// Method to call on entity saved when first added
+        /// </summary>
+        internal virtual void AddingEntity()
+        {
+            CreatedDate = DateTime.UtcNow;
+            ModifiedDate = DateTime.UtcNow;
+        }
+
+        /// <summary>
+        /// Method to call on entity saved/updated
+        /// </summary>
+        internal virtual void UpdatingEntity()
+        {
+            ModifiedDate = DateTime.UtcNow;
+        }
+
+        /// <summary>
+        /// Tracks the properties that have changed
+        /// </summary>
+        private readonly IDictionary<string, bool> _propertyChangedInfo = new Dictionary<string, bool>();
+
+        /// <summary>
+        /// Returns true if the property referenced by the name has been changed on the class
+        /// </summary>
+        /// <param name="propertyName"></param>
+        /// <returns></returns>
+        public bool IsPropertyDirty(string propertyName)
+        {
+            return _propertyChangedInfo.Any(x => x.Key == propertyName);
+        }
+
+        /// <summary>
+        /// Returns true if any properties have been changed on the class
+        /// </summary>
+        /// <returns></returns>
+        public bool IsDirty()
+        {
+            return _propertyChangedInfo.Any();
+        }
+
+        /// <summary>
+        /// Resets dirty properties by clearing the dictionary used to track changes.
+        /// </summary>
+        internal void ResetDirtyProperties()
+        {
+            _propertyChangedInfo.Clear();
+        }
+
+        /// <summary>
+        /// Indicates whether the current entity has an identity, eg. Id.
+        /// </summary>
+        public virtual bool HasIdentity
+        {
+            get
+            {
+                return _hasIdentity;
+            }
+            protected set
+            {
+                _hasIdentity = value;
+            }
+        }
+
+        public static bool operator ==(Entity left, Entity right)
+        {
+            if (ReferenceEquals(null, left))
+                return false;
+
+            return left.Equals(right);
+        }
+
+        public static bool operator !=(Entity left, Entity right)
+        {
+            return !(left == right);
+        }
+
+        public virtual bool SameIdentityAs(IEntity other)
+        {
+            if (ReferenceEquals(null, other))
+                return false;
+            if (ReferenceEquals(this, other))
+                return true;
+
+            return SameIdentityAs(other as Entity);
+        }
+
+        public virtual bool Equals(Entity other)
+        {
+            if (ReferenceEquals(null, other))
+                return false;
+            if (ReferenceEquals(this, other))
+                return true;
+
+            return SameIdentityAs(other);
+        }
+
+        public virtual Type GetRealType()
+        {
+            return GetType();
+        }
+
+        public virtual bool SameIdentityAs(Entity other)
+        {
+            if (ReferenceEquals(null, other))
+                return false;
+
+            if (ReferenceEquals(this, other))
+                return true;
+
+            if (GetType() == other.GetRealType() && HasIdentity && other.HasIdentity)
+                return other.Id.Equals(Id);
+
+            return false;
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(null, obj))
+                return false;
+            if (ReferenceEquals(this, obj))
+                return true;
+
+            return SameIdentityAs(obj as IEntity);
+        }
+
+        public override int GetHashCode()
+        {
+            if (!_hash.HasValue)
+                _hash = !HasIdentity ? new int?(base.GetHashCode()) : new int?(Id.GetHashCode() * 397 ^ GetType().GetHashCode());
+            return _hash.Value;
+        }
+    }
+}