Question

我正在尝试为我的Entity Framework模型创建一个Generic类。

using UM4RS.persistance;
using UM4RS.Persistance;

public abstract class MyEntity<TObject>  where TObject : class, IBaseEntity
{
    static readonly ModelContext ModelContext = new ModelContext();

    // class method to save object
    public static TObject Save(TObject t)
    {
        if (t == null) return null;       
        ModelContext.Set<TObject>().Add(t);
        ModelContext.SaveChanges();
        return t;
    }

    // instance method to save the current instance
    public void Save()
    {
         Save(this); //<- ERROR: Cannot convert MyEnttity<TObject> to TObject

        // Also tried
        ModelContext.Set<TObject>().Add(this); //<- Same error here
        ModelContext.SaveChanges();
    }
}

我的模型类继承自MyEntity

public class User : MyEntity<User>, IBaseEntity
{
    ...
}

最后，我要归档的是：

User usr = new User();
usr.Save(); // <- Call the instance method

Answer 1

由于User类是IBaseEntity，而TObject依次为var baseEntity = this as TObject; Debug.Assert(baseEntity!=null);//assert that its not violated Save(baseEntity); ModelContext.Set<TObject>().Add(baseEntity);，您可以将其投射

UPDATE tbl_Items
INNER JOIN 

(SELECT *
FROM tbl_Inventory
INNER JOIN tbl_Inputs
ON tbl_Inventory.class = tbl_Inputs.class)

ON tbl_Items.PRODUCT_ID = tbl_Inputs.PRODUCT_ID

SET tbl_Items.status = tbl_Inventory.status

WHERE tbl_Items.status <> tbl_Inventory.status

C＃通用类EF6，保存实例（this）

1 个答案: