使用DAL C＃的实体框架

Question

I am trying to make an invoice managing application.

When creating DAL object, I have to repeat Add and Delete functions for every table.

For example:

public class MyDBProcessor :IMyDBProcessor {
    tpEntities tp=new tpEntities();
    public void AddCustomerToDB(tblCustomers Customer) { tp.tblCustomers.Add(Customer); tp.SaveChanges();}
    public void AddOrderToDB(tblOrders Order) { tp.tblOrders.Add(Order); tp.SaveChanges(); }

    public tblCustomers GetCustomerFromDB(string CustomerID) { return tp.tblCustomers.Where(x => x.ID == CustomerID);   }
    public tblOrders GetOrderFromDB(string OrderID) { return tp.tblOrders.Where(x => x.ID == OrderID); }
}

It is very frustrating because there are so many tables. I want to change DAL interface like this:

public interface IMyGenericDBProcessor {
    void AddToDB<T>(T Record);
    T GetFromDB<T>(int RecordID);
}

So, when I change db engine MySQL to SQL Server or vice versa. How can I write a class that implemets IMyGenericDBProcessor ?

Thank you,

Answer 1

Adding is easy:

public interface IMyGenericDBProcessor
{
    void AddToDB<T>(T Record) where T : class;
}

public class MyDBProcessor : IMyGenericDBProcessor 
{
    public void AddToDB<T>(T record) where T : class
    {
        using(var tp = new tpEntities())
            tp.Set<T>().Add(record);
    }
}

GetFromDb would be more complicated because you'd have to determine, based on the entity context's metadata, which property comprises the ID, and then construct an expression tree based on that.