如何处理实体框架中的主键5代码首先

如何处理实体框架中的主键5代码首先

本文介绍了如何处理实体框架中的主键5代码首先的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

在我的EF5代码优先模型中,如果数据库设置主键,创建新记录的效果会更好。我正在使用Guid的主键,如果设置了 DatabaseGeneratedOption.Identity ,SQL Server将始终创建 uniqueidentifier



但是,当我尝试初始种子数据库时,会导致问题。如果我在我的种子方法中设置Guid,SQL Server会覆盖它。如果我没有设定Guid,我每次都会获得新的记录。什么是建议的解决方案来种子数据库使用预设的Guid和保持 DatabaseGeneratedOption.Identity 设置为我的正常操作?



示例类模型:

  [Key] 
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id {get;组; }
public RecordName {get;组; }
public DateTime?创建{get;组; }
public DateTime?更新{get;组;

种子方法示例:

  var record = new Record()
{
Id = new Guid(3B80725E-9550-4933-807F-C2FAA0942225),
RecordName =New记录,
Created = DateTime.UtcNow,
更新= DateTime.UtcNow,
};
context.Record.AddOrUpdate(record);
context.SaveChanges();


解决方案

AddOrUpdate有一个覆盖,允许您指定密钥





所以你需要提供自然键的方法:

  context.Record.AddOrUpdate(c => c.RecordName,new Record()
{
RecordName =New Record,
Created = DateTime.UtcNow,
更新= DateTime.UtcNow,
})


In my EF5 code-first models, creation of new records works better if the database sets the primary key. I am using a Guid for primary key and if DatabaseGeneratedOption.Identity is set, SQL Server will always create the uniqueidentifier.

However, this causes issues when I am trying to initially seed the database. If I set the Guid in my seed method, SQL Server overrides it. If I don't set the Guid, I get a new record every time. What is a recommended solution to seed the database using pre-set Guids and keep DatabaseGeneratedOption.Identity set for my normal operations?

Example class model:

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid Id { get; set; }
public RecordName { get; set; }
public DateTime? Created { get; set; }
public DateTime? Updated { get; set; }

Example seed method:

var record = new Record()
            {
                Id = new Guid("3B80725E-9550-4933-807F-C2FAA0942225"),
                RecordName = "New Record",
                Created = DateTime.UtcNow,
                Updated = DateTime.UtcNow,
             };
context.Record.AddOrUpdate(record);
context.SaveChanges();
解决方案

AddOrUpdate has an override that allows you to specify the key

From MSDN

So you need to supply the method with the natural key:

context.Record.AddOrUpdate(c => c.RecordName, new Record()
            {
                RecordName = "New Record",
                Created = DateTime.UtcNow,
                Updated = DateTime.UtcNow,
             })

这篇关于如何处理实体框架中的主键5代码首先的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

08-15 15:06