如何停止添加dbo的Entity Framework 5迁移.成为关键名称？

Question

我开始使用Entity Framework 4.3 Code First进行手动迁移和SQL Express 2008并最近更新到EF5(在VS 2010中),并注意到现在当我更改类似外键约束时,迁移代码会添加"dbo".到表名的开头,因此它构造的外键名称对于现有约束是不正确的(现在通常看起来很奇怪).

EF 4.3中的原始迁移脚本(注意ForeignKey("Products",t => t.Product_Id)):

    CreateTable(
        "Products",
        c => new
            {
                Id = c.Int(nullable: false, identity: true),
                ProductName = c.String(),
            })
        .PrimaryKey(t => t.Id);

    CreateTable(
        "KitComponents",
        c => new
            {
                Id = c.Int(nullable: false, identity: true),
                Component_Id = c.Int(),
                Product_Id = c.Int(),
            })
        .PrimaryKey(t => t.Id)
        .ForeignKey("Products", t => t.Component_Id)
        .ForeignKey("Products", t => t.Product_Id)
        .Index(t => t.Component_Id)
        .Index(t => t.Product_Id);

生成的外键名称:FK_KitComponents_Products_Product_Id FK_KitComponents_Products_Component_Id

如果我然后升级到EF5并更改外键,则迁移代码看起来像(注意"dbo.KitComponents"和"dbo.Products"而不是"KitComponents"和"Products"):

DropForeignKey("dbo.KitComponents", "Product_Id", "dbo.Products");
DropIndex("dbo.KitComponents", new[] { "Product_Id" });

并且update-database失败并显示以下消息:' FK_dbo.KitComponents_dbo.Products_Product_Id '不是约束.无法删除约束.查看以前的错误.

因此,从EF5开始,约束命名已从FK_KitComponents_Products_Product_Id更改为FK_dbo.KitComponents_dbo.Products_Product_Id(使用dbo.前缀)

我怎样才能让EF5在EF 4.3中表现得如此,所以我不必改变它吐出的每一个新的迁移代码？

我一直无法找到任何关于为什么会改变以及如何应对的发布说明:(

Answer 1

您可以通过对CSharpMigrationCodeGenerator类进行子类化来自定义生成的代码:

class MyCodeGenerator : CSharpMigrationCodeGenerator
{
    protected override void Generate(
        DropIndexOperation dropIndexOperation, IndentedTextWriter writer)
    {
        dropIndexOperation.Table = StripDbo(dropIndexOperation.Table);

        base.Generate(dropIndexOperation, writer);
    }

    // TODO: Override other Generate overloads that involve table names

    private string StripDbo(string table)
    {
        if (table.StartsWith("dbo."))
        {
            return table.Substring(4);
        }

        return table;
    }
}

然后在迁移配置类中进行设置:

class Configuration : DbMigrationsConfiguration<MyContext>
{
    public Configuration()
    {
        CodeGenerator = new MyCodeGenerator();
    }
}

Answer 2

对于自动迁移，请使用以下代码：

public class MyOwnMySqlMigrationSqlGenerator : MySqlMigrationSqlGenerator
{
    protected override MigrationStatement Generate(AddForeignKeyOperation addForeignKeyOperation)
    {
        addForeignKeyOperation.PrincipalTable = addForeignKeyOperation.PrincipalTable.Replace("dbo.", "");
        addForeignKeyOperation.DependentTable = addForeignKeyOperation.DependentTable.Replace("dbo.", "");
        MigrationStatement ms = base.Generate(addForeignKeyOperation);
        return ms;
    }
}

并在配置上进行设置：

SetSqlGenerator("MySql.Data.MySqlClient", new MyOwnMySqlMigrationSqlGenerator());