将更改保存到映射到视图的实体

Question

我可以使用 Entity Framework 来保存对视图的更改吗？

我有一个映射到视图的实体。

[Table("MyView")]
public class MyEntity
{
    public long MyEntityId { get; set; }

    public string Name { get; set; }
}

View本身是这样的：

CREATE VIEW MyView AS 
SELECT 
    t.MyEntityId,
    t.Name,
FROM 
    MyTable t

我可以使用 Entity Framework 更改跟踪来保存对此视图的更改吗？那么这样的事情可能吗：

var record = Context.MyEntity.Where(e => e.MyEntityId == 150).FirstOrDefault();
record.Name = "New Name";
Context.SaveChanges();

Answer 1

看起来 Entity Framework 不关心实体是否映射到视图或 Table...它只会创建相同的更新脚本。对于上面的示例，EF 生成以下脚本：

UPDATE [MyView] SET [Name]=@gp1 WHERE [MyEntityId] = 150
-- @gp1: 'New Name' (Type = String, IsNullable = false, Size = 8)

因此 EF 不会引入任何更新视图的额外限制...但是我们仍然有更新视图的 RDBMS 特定限制...例如，在 SQL 服务器中，视图可以是已更新 subject to the following limitations：

If the view contains joins between multiple tables, you can only insert and update one table in the view, and you can't delete rows.

You can't directly modify data in views based on union queries. You can't modify data in views that use GROUP BY or DISTINCT statements.

All columns being modified are subject to the same restrictions as if the statements were being executed directly against the base table.

Text and image columns can't be modified through views.

There is no checking of view criteria. For example, if the view selects all customers who live in Paris, and data is modified to
either add or edit a row that does not have City = 'Paris', the data
will be modified in the base table but not shown in the view, unless
WITH CHECK OPTION is used when defining the view.

将更改保存到映射到视图的实体

Saving change to an Entity which is mapped to a View

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