EF Migrations正在复制语句

Question

我做了一个配置更改，这就是EF6提出的迁移

 public override void Up()
    {
        DropForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents");
        DropForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents");
        DropIndex("dbo.AdditionalCostLines", new[] { "OrderID" });
        DropIndex("dbo.AdditionalCostLines", new[] { "OrderID" });
        CreateIndex("dbo.AdditionalCostLines", "OrderID");
        CreateIndex("dbo.AdditionalCostLines", "OrderID");
        AddForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents", "ID");
        AddForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents", "ID");
    }

    public override void Down()
    {
        DropForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents");
        DropForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents");
        DropIndex("dbo.AdditionalCostLines", new[] { "OrderID" });
        DropIndex("dbo.AdditionalCostLines", new[] { "OrderID" });
        CreateIndex("dbo.AdditionalCostLines", "OrderID");
        CreateIndex("dbo.AdditionalCostLines", "OrderID");
        AddForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents", "ID", cascadeDelete: true);
        AddForeignKey("dbo.AdditionalCostLines", "OrderID", "dbo.Documents", "ID", cascadeDelete: true);

为什么每个陈述都是重复的？

我正在使用实体框架版本6。

迁移本身也是无用的，因为它删除并重新创建相同的索引和外键，但是我的上下文已经改变了，所以我必须嵌入一个迁移记录才能运行代码。在这里，由更新数据库-script提供生成的SQL：

IF object_id(N'[dbo].[FK_dbo.AdditionalCostLines_dbo.Documents_OrderID]', N'F') IS NOT NULL
ALTER TABLE [dbo].[AdditionalCostLines] DROP CONSTRAINT         [FK_dbo.AdditionalCostLines_dbo.Documents_OrderID]
IF EXISTS (SELECT name FROM sys.indexes WHERE name = N'IX_OrderID' AND object_id = object_id(N'[dbo].[AdditionalCostLines]', N'U'))
DROP INDEX [IX_OrderID] ON [dbo].[AdditionalCostLines]
CREATE INDEX [IX_OrderID] ON [dbo].[AdditionalCostLines]([OrderID])
ALTER TABLE [dbo].[AdditionalCostLines] ADD CONSTRAINT [FK_dbo.AdditionalCostLines_dbo.Documents_OrderID] FOREIGN KEY ([OrderID]) REFERENCES [dbo].[Documents] ([ID])

编辑:包含更多示例代码：

  public class Document
{
[Key]
public int ID { get; set; }
public virtual Vendor Vendor { get; set; }
[ForeignKey("Vendor")]
public int? VendorID { get; set; }

[Display(Name = "Reference Number")]
public string ReferenceNumber { get; set; }
public string Notes { get; set; }

public virtual List<OrderLine> Lines { get; set; }
}

public class Order : Document
{
    //Fields Atop Documents base fields for order style documents.


    [Display(Name = "Payment Terms")]
    public virtual PaymentTerms PaymentTerms { get; set; }
    [ForeignKey("PaymentTerms")]
    public int? PaymentTermsID { get; set; }

    //Collections

    public virtual List<AdditionalCostLine> AdditionalCosts { get; set; }
}

public class WorkOrder : Order
{
   [Display(Name = "Est. Ship Date")]
   [DataType(DataType.Date), DisplayFormat(DataFormatString = "{0:MM/dd/yyyy}", ApplyFormatInEditMode = true)]
   public DateTime? EstimatedShipDate { get; set; }

public virtual List<WorkOrderLineChange> LineChanges { get; set; }
}

public class AdditionalCostLine
{
    [Key]
    public int ID { get; set; }

    public virtual Order Order { get; set; }
    [ForeignKey("Order")]
    public int OrderID { get; set; }

    public string Description { get; set; }

    [DisplayFormat(DataFormatString = "{0:$0.00#}")]
    public decimal Rate { get; set; }
    public int Quantity { get; set; }

    public virtual AdditionalCostType AdditionalCostType { get; set; }
    [ForeignKey("AdditionalCostType")]
    public int AdditionalCostTypeID { get; set; }

    [NotMapped]
    public decimal Amount
    {
        get
        {
            return Rate * Quantity;
        }
    }
}

Answer 1

虽然Store模型( EF生成的sql )没有改变，但由于类的改变，EntityFramework认为模型确实发生了变化，并且需要搭建迁移的支架。您可能会得到重复迁移，因为该表是从您的模型中引用两次。因为您知道这是应用程序的NOP，所以生成一个只更新存储在数据库中的快照的空迁移是安全的。

若要从包管理器控制台生成空迁移，请执行以下操作：

PM> Add-Migration emptyMigration -IgnoreChanges
PM> Update-Database

请记住，通过生成一个空迁移，您可以保证EF数据库模型将与项目中的代码匹配。