Layers Pattern in Practice

using System;
using System.ComponentModel;

namespace BillsEntityLib
{
    /// <summary>
    /// Bill entity object
    /// </summary>
    [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")]
    [System.SerializableAttribute()]
    [System.Diagnostics.DebuggerStepThroughAttribute()]
    [System.ComponentModel.DesignerCategoryAttribute("code")]
    [System.Xml.Serialization.XmlTypeAttribute(Namespace = "http://tempuri.org/billschema.xsd")]
    public partial class Bill: INotifyPropertyChanged
    {

        private string nameField;

        private System.DateTime dueDateField;

        private decimal amountField;

        private System.DateTime addedOnField;

        private string statusField;

        private string idField;

        [NonSerialized]
        private BillStatus billStatusField; //not serialized //

        #region Constructors
        /// <summary>
        /// Parameterless constructor
        /// </summary>
        public Bill() { }
        /// <summary>
        /// Bill's constructor
        /// </summary>
        /// <param name="name">Bill's name</param>
        /// <param name="dueDate">Duedate</param>
        /// <param name="amount">Amount</param>
        /// <param name="addedOn">Added On</param>
        /// <param name="status">Status</param>
        /// <param name="id">Bill's Id</param>
        public Bill(string name, DateTime dueDate, decimal amount, DateTime addedOn, string status, string id)
            : this()
        {
            nameField = name;
            dueDateField = dueDate;
            amountField = amount;
            addedOnField = addedOn;
            statusField = status;
            billStatusField = BillHelper.Convert(status);
            idField = id;
        }
        /// <summary>
        /// Bill's constructor
        /// </summary>
        /// <param name="name">Bill's name</param>
        /// <param name="dueDate">Duedate</param>
        /// <param name="amount">Amount</param>
        /// <param name="addedOn">Added On</param>
        /// <param name="status">Status</param>
        /// <param name="id">Bill's Id</param>
        public Bill(string name, DateTime dueDate, decimal amount, DateTime addedOn, BillStatus status, Guid id)
            : this(name, dueDate, amount, addedOn, status.ToString(), id.ToString())
        { }
        /// <summary>
        /// Bill's constructor
        /// </summary>
        /// <param name="name">Bill's name</param>
        /// <param name="dueDate">Duedate</param>
        /// <param name="amount">Amount</param>
        /// <param name="addedOn">Added On</param>
        /// <param name="status">Status</param>
        /// <param name="id">Bill's Id</param>
        public Bill(string name, DateTime dueDate, decimal amount, DateTime addedOn, string status, Guid id)
            : this(name, dueDate, amount, addedOn, status, id.ToString())
        { }

        #endregion

        #region Properties
        /// <summary>
        /// Bill's name
        /// </summary>
        public string Name
        {
            get
            {
                return this.nameField;
            }
            set
            {
                this.nameField = value;
                this.OnPropertyChanged(new BillPropertyChangeEventArgs(this.idField, "Name"));
            }
        }

        /// <summary>
        /// Due date
        /// </summary>
        public System.DateTime DueDate
        {
            get
            {
                return this.dueDateField;
            }
            set
            {
                this.dueDateField = value;
                this.OnPropertyChanged(new BillPropertyChangeEventArgs(this.idField, "DueDate"));
            }
        }

        /// <summary>
        /// Amount of money to pay
        /// </summary>
        public decimal Amount
        {
            get
            {
                return this.amountField;
            }
            set
            {
                this.amountField = value;
                this.OnPropertyChanged(new BillPropertyChangeEventArgs(this.idField, "Amount"));
            }
        }

        /// <summary>
        /// Added on
        /// </summary>
        public System.DateTime AddedOn
        {
            get
            {
                return this.addedOnField;
            }
            set
            {
                this.addedOnField = value;
                this.OnPropertyChanged(new BillPropertyChangeEventArgs(this.idField, "AddedOn"));
            }
        }

        /// <summary>
        /// Bill's status
        /// </summary>
        public string Status
        {
            get
            {
                return this.statusField;
            }
            set
            {
                this.billStatusField = BillHelper.Convert(value);
                this.statusField = value;
                this.OnPropertyChanged(new BillPropertyChangeEventArgs(this.idField, "Status"));
            }
        }
        /// <summary>
        /// Bill's status
        /// </summary>
        public BillStatus BillStatus
        {
            get 
            {
                return this.billStatusField;
            }
            set 
            {
                this.statusField = value.ToString();
                this.billStatusField = value;
                this.OnPropertyChanged(new BillPropertyChangeEventArgs(this.idField, "Status"));
            }
        }

        /// <summary>
        /// Bill's ID
        /// </summary>
        /// <remarks>Represets a XML attribute in the serialized xml document</remarks>
        [System.Xml.Serialization.XmlAttributeAttribute()]
        public string ID
        {
            get
            {
                return this.idField;
            }
            set
            {
                this.idField = value;
                this.OnPropertyChanged(new BillPropertyChangeEventArgs(this.idField, "ID"));
            }
        }
        #endregion

        #region Object ovverides
        /// <summary>
        /// Converts bill into string representation
        /// </summary>
        /// <returns>String representation of the bill</returns>
        public override string ToString()
        {
            return "Name=" + nameField + "\n"
                + "DueDate=" + dueDateField.ToString() + "\n"
                + "Amount=" + amountField.ToString() + "\n"
                + "AddedOn=" + addedOnField.ToString() + "\n"
                + "Status=" + statusField.ToString() + "\n"
                + "ID=" + idField + "\n";
        }
        #endregion

        #region INotifyPropertyChanged Members
        /// <summary>
        /// Property Changed Event Handler
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;
        /// <summary>
        /// Invoke OnPropertyChanged every time a property of an object is changed
        /// </summary>
        /// <param name="args">BillPropertyEventArgs - event arguments</param>
        protected virtual void OnPropertyChanged(BillPropertyChangeEventArgs args)
        { 
            //save delegate into a temporary field for thread-safety
            PropertyChangedEventHandler temp = this.PropertyChanged;
            if (temp != null)
            {
                temp.Invoke(this, args);    //invoke all subscribers
            }
        }
        #endregion
    }
}