使用EF的常见LINQ方法(Common LINQ method using EF)

 正如您已经看到的那样，无法将BusClient传递给AddToClients 。 您必须通过复制非常难看的属性从Insert方法中的BusClient创建Client ： 
 
public void Insert()
{
    using(MyBIEntities db = new MyBIEntities())
    {
        Client client = new Client();

        client.CityId = this.CityId;
        client.Name = this.Name;
        client.RegisterDate = this.RegisterDate;

        db.AddToClients(client);
        db.SaveChanges();
    }
}
 
 重新思考设计。 从实体（ Client ）派生类（ BusClient ），我看不到任何好处。 如果您无法更改Client类，则可以创建扩展方法... 
 
public static class Extensions
{
    public static bool Validate(this Client client)
    {
        // Run validation rules on client object
    }
}
 
 ...或用于验证的单独类： 
 
public class Validator
{
    public bool Validate(Client client)
    {
        // Run validation rules on client object
    }
}
 
 我也会考虑这个单独的Insert方法。 虽然这可能在您的示例中起作用，但只要您必须操纵更复杂的对象图，它就会导致麻烦（或至少变得无用）。 在这种情况下，您将需要一个ObjectContext用于整个操作。 对于每个INSERT，UPDATE或DELETE，您不能再使用单独的ObjectContext工作了。 
 
 因此，我建议从特殊类中删除DB操作并将其放入主例程中。 整个事情可能看起来像： 
 
try
{
    using(MyBIEntities db = new MyBIEntities())
    {
        Client client = new Client();

        client.CityId = int.Parse(ddlCity.SelectedValue());
        client.Name = txtName.Text;
        client.RegisterDate = Convert.ToDateTime("txtDate.Text");

        if (client.Validate())
        // works with the extension method, or with the Validator use:
        // Validator validator = new Validator();
        // if (validator.Validate(client))
        {
            db.AddToClients(client);
            db.SaveChanges();
        }
    }
}
catch (Exception ex)
{
    //Catching errors
}
 
 在此示例中， BusClient类不再存在。 

As you already have seen you cannot pass in a BusClient into AddToClients. You would have to create a Client from the BusClient in your Insert method by copying the properties which is quite ugly:
 
public void Insert()
{
    using(MyBIEntities db = new MyBIEntities())
    {
        Client client = new Client();

        client.CityId = this.CityId;
        client.Name = this.Name;
        client.RegisterDate = this.RegisterDate;

        db.AddToClients(client);
        db.SaveChanges();
    }
}
 
Rethink the design. I cannot see a benefit with deriving a class (BusClient) from an Entity (Client). If you cannot change the Client class you could create either an extension method ...
 
public static class Extensions
{
    public static bool Validate(this Client client)
    {
        // Run validation rules on client object
    }
}
 
... or a separate class for your validation:
 
public class Validator
{
    public bool Validate(Client client)
    {
        // Run validation rules on client object
    }
}
 
I would also think twice about this separate Insert method. While this may work in your example it can cause trouble (or at least become useless) as soon as you have to manipulate a more complex object graph. In such a case you will need one single ObjectContext for the whole operation. You cannot work then anymore with a separate ObjectContext for each INSERT, UPDATE or DELETE an so on.
 
So, I'd recommend to remove the DB operations from your special class and put this into the main routine. The whole thing could then look like:
 
try
{
    using(MyBIEntities db = new MyBIEntities())
    {
        Client client = new Client();

        client.CityId = int.Parse(ddlCity.SelectedValue());
        client.Name = txtName.Text;
        client.RegisterDate = Convert.ToDateTime("txtDate.Text");

        if (client.Validate())
        // works with the extension method, or with the Validator use:
        // Validator validator = new Validator();
        // if (validator.Validate(client))
        {
            db.AddToClients(client);
            db.SaveChanges();
        }
    }
}
catch (Exception ex)
{
    //Catching errors
}
 
The BusClient class doesn't exist anymore in this example.