实体框架包管理器控制台问题

Question

I have EF 5 and I added the following table and it added successfully as shown in code snippet #1. However, I want the UserID to be a foreign key that references the Users table and if I did that, then my code would have looked like code snippet# 2. Without deleting this new table, can you please tell me how I can now make the UserID to be a foreign key that references Users table. Thank you so much. I'm using Package Manager Console to achieve this.

Code snippet #1

public partial class Initialignorechanges : DbMigration
{
    public override void Up()
    {
        CreateTable(
            "dbo.Favorite",
            c => new
            {
                ID = c.Int(nullable: false, identity: true),
                UserID = c.Int(nullable: false),
                UserName = c.String(nullable: true, maxLength: 25, unicode: false),
                FavoritedUserID = c.Int(nullable: false),
                FavoritedUserName = c.String(nullable: true, maxLength: 25, unicode: false),
                FavoritedDate = c.DateTime(),
                ShowToUser = c.Boolean(nullable: false),
                ShowToFavoritedUser = c.Boolean(nullable: false),
            })
            .PrimaryKey(t => t.ID);                
    }

    public override void Down()
    {            
        DropTable("dbo.Favorite");
    }
}

Code snippet #2:

public partial class Initialignorechanges : DbMigration
{
    public override void Up()
    {
        CreateTable(
            "dbo.Favorite",
            c => new
            {
                ID = c.Int(nullable: false, identity: true),
                UserID = c.Int(nullable: false),
                UserName = c.String(nullable: true, maxLength: 25, unicode: false),
                FavoritedUserID = c.Int(nullable: false),
                FavoritedUserName = c.String(nullable: true, maxLength: 25, unicode: false),
                FavoritedDate = c.DateTime(),
                ShowToUser = c.Boolean(nullable: false),
                ShowToFavoritedUser = c.Boolean(nullable: false),
            })
            .PrimaryKey(t => t.ID)
            .ForeignKey("dbo.Users", t => t.UserID, cascadeDelete: true)
            .Index(t => t.UserID);
    }

    public override void Down()
    {
        DropIndex("dbo.Favorite", new[] { "UserID" });
        DropForeignKey("dbo.Favorite", "UserID", "dbo.Users");
        DropTable("dbo.Favorite");
    }
}

Answer 1

Take a look at Code-Based Migration in Entity Framework 6 .

Now, you have to create a migration class using the Add-Migration command with the name of your migration class, as shown below.

After creating a migration file using the add-migration command, you have to update the database. Execute the Update-Database command to create or modify a database schema. Use the –verbose option to view the SQL statements being applied to the target database.

At this point, the database will be created or updated. Now, whenever you change the domain classes, execute Add-Migration with the name parameter to create a new migration file and then execute the Update-Database command to apply the changes to the database schema.