c# - Entity Framework 读取列但阻止更新

Question

给定一个包含历史数据但不再填充的列的数据库表， Entity Framework 中是否有一种方法可以读取该列，但在使用相同的模型对象时阻止它被更新？

比如我有一个对象

public class MyObject
{
    public string CurrentDataColumnName { get; set; }
    public string HistoricDataColumnName { get; set; }
}

根据文档，我认为我无法执行以下任一操作，因为这将停止 EF 读取数据并保留数据。

(1) 用以下属性修饰 HistoricDataColumnName 属性

[NotMapped]

(2) 将以下内容添加到我的EntityTypeConfiguration for MyObject

Ignore(x => x.HistoricDataColumnName)

Answer 1

您可以将列标记为已计算，以防止 Entity Framework 更新/插入该列。

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public string HistoricDataColumnName { get; set; }

---

DatabaseGenerated

An important database features is the ability to have computed properties. If you're mapping your Code First classes to tables that contain computed columns, you don't want Entity Framework to try to update those columns. But you do want EF to return those values from the database after you've inserted or updated data. You can use the DatabaseGenerated annotation to flag those properties in your class along with the Computed enum. Other enums are None and Identity.