#眉標=ADO.NET Entity、WPF、WCF
#副標=ADO.NET Entity Framework運作機制（2）
#大標=透過WCF取用ADO.NET Entity Framework
#作者=文／圖		黃忠成



==<box>===========
程式1：IService.cs
..........
public interface IService
{
	[OperationContract]
	List<NorthwindModel.Customers> GetCustomers();
}
==<end>==============




==<box>===========
程式2：Service.cs
...........
public class Service : IService
{    
	public List<NorthwindModel.Customers> GetCustomers()
	{
        NorthwindModel.NorthwindEntities entities = new NorthwindModel.NorthwindEntities();
        return (from s1 in entities.Customers select s1).ToList();
	}
}
==<end>==============




===<反灰>=============
public void UpdateCustomers(Customers [] changeData)
==<end>==============




==<box>===========
程式3
public enum ChangeMode
{
    Modified,
    Added,
    Delete
}
[DataContract]
public class CustomersChangeData
{
    [DataMember]
    public ChangeMode Mode { get; set; }
    [DataMember]
    public NorthwindModel.Customers Data { get; set; }
}
==<end>==============



==<box>===========
程式4
public void UpdateCustomers(CustomersChangeData[] changeData)
    {
        NorthwindModel.NorthwindEntities entities = new NorthwindModel.NorthwindEntities();
        //處理刪除
        foreach (CustomersChangeData item in changeData)
        {
            if (item.Mode == ChangeMode.Delete)
            {
                var result = (from s1 in entities.Customers where 
                      s1.CustomerID == item.Data.CustomerID select s1).First();
                entities.DeleteObject(result);
            }      
        }
        //處理新增
        foreach (CustomersChangeData item in changeData)
        {
            if (item.Mode == ChangeMode.Added)
                entities.AddToCustomers(item.Data);
        }
        //處理變動
        foreach (CustomersChangeData item in changeData)
        {
            if (item.Mode == ChangeMode.Modified)
            {
                entities.GetObjectByKey(entities.GetEntityKey("Customers", item.Data));
                entities.ApplyPropertyChanges("Customers", item.Data);
            }
        }
        entities.SaveChanges();
    }
==<end>==============





==<box>===========
注釋
其實讀者們也可以用類似Delete的處理方式來處理變動，兩者之間的不同之處在於，呼叫GetObjectByKey函式時不需要知道主鍵為何(ADO.NET Entity Framework會由Entity Class探知主鍵)，而下達LINQ Expression時則需要明確使用主鍵來比對。
==<end>==============





==<box>===========
程式5	
......
private List<CustomersChangeData> _changedItems = 
                     new List<CustomersChangeData>();
........
private void Delete_Click(object sender, RoutedEventArgs e)
{
            if (_isAddMode)
                Cancel_Click(null, null);
            _changedItems.Add(new CustomersChangeData() 
                { Mode = ChangeMode.Delete, Data = (Customers)view.CurrentItem });
            bindingList.Remove(view.CurrentItem);
}

private void Cancel_Click(object sender, RoutedEventArgs e)
{
            textBox1.Focus();
            if (_isAddMode)
            {
                ((ICancelAddNew)bindingList).CancelNew(view.CurrentPosition);
                _isAddMode = false;
            }
 }

 private void Save_Click(object sender, RoutedEventArgs e)
{
            textBox1.Focus();
            if (_isAddMode)
            {
                ((ICancelAddNew)bindingList).EndNew(view.CurrentPosition);
                _changedItems.Add(new CustomersChangeData() 
                     { Mode = ChangeMode.Added, Data = (Customers)view.CurrentItem });
            }
            else
                _changedItems.Add(new CustomersChangeData() 
                   { Mode = ChangeMode.Modified, Data = (Customers)view.CurrentItem });
            _isAddMode = false;
}
==<end>==============