IDENTITY_INSERT期间的EntityFramework 6代码优先接种 [英] IDENTITY_INSERT during seeding with EntityFramework 6 Code-First

问题描述

我有一个具有自动识别（INT）列的实体。由于数据种子的一部分，我想用特殊标识值在我的系统标准数据，在那之后我想有数据库整理出的id值。

I have an entity that has an Auto-identity (int) column. As part of the data-seed I want to use specific identifier values for the "standard data" in my system, after that I want to have the database to sort out the id value.

到目前为止，我已经能够将IDENTITY为On作为插入批次的一部分，但实体框架不产生插入语句包含的ID。这是有意义的作为模型认为数据库应提供的值，但在这种情况下，我想要提供的值

So far I've been able to set the IDENTITY_INSERT to On as part of the insert batch, but Entity Framework does not generate an insert statement that include the Id. This makes sense as the model thinks the database should provide the value, but in this case I want to provide the value.

模型（伪码）

public class ReferenceThing
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id{get;set;}
    public string Name{get;set;}
}

public class Seeder
{
    public void Seed (DbContext context)
    {

        var myThing = new ReferenceThing
        {
            Id = 1,
            Name = "Thing with Id 1"
        };

        context.Set<ReferenceThing>.Add(myThing);

        context.Database.Connection.Open();
        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing ON")

        context.SaveChanges();  // <-- generates SQL INSERT statement
                                //     but without Id column value

        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing OFF")
    }
}

任何人能提供任何见解或建议？

Anyone able to offer any insight or suggestions?

推荐答案

所以，我可能已经解决了这一个诉诸产生我自己的SQL插入语句中包含的ID列。这感觉就像一个可怕的黑客，但它的工作原理： - /

So I might have resolved this one by resorting to generating my own SQL insert statements that include the Id column. It feels like a terrible hack, but it works :-/

public class Seeder
{
    public void Seed (DbContext context)
    {

        var myThing = new ReferenceThing
        {
            Id = 1,
            Name = "Thing with Id 1"
        };

        context.Set<ReferenceThing>.Add(myThing);

        context.Database.Connection.Open();
        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing ON")

        // manually generate SQL & execute
        context.Database.ExecuteSqlCommand("INSERT ReferenceThing (Id, Name) " +
                                           "VALUES (@0, @1)", 
                                           myThing.Id, myThing.Name);

        context.Database.ExecuteSqlCommand("SET IDENTITY_INSERT ReferenceThing OFF")
    }
}

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