我刚刚将 Microsoft.AspNet.Identity.EntityFramework 库更新到最新版本 (2.0.0.0)，我发现创建表格时出现了一些错误。当我生成迁移代码(Up 和 Down 方法)时，我无法将更改上传到数据库，因为在执行“Updata-Database”时我遇到了索引问题

Specified key was too long; max key length is 767 bytes

要执行的代码:

public override void Up()
    {
        CreateTable(
            "dbo.AspNetRoles",
            c => new
                {
                    Id = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    Name = c.String(nullable: false, maxLength: 256, storeType: "nvarchar"),
                })
            .PrimaryKey(t => t.Id)
            .Index(t => t.Name, unique: true, name: "RoleNameIndex");

        CreateTable(
            "dbo.AspNetUserRoles",
            c => new
                {
                    UserId = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    RoleId = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                })
            .PrimaryKey(t => new { t.UserId, t.RoleId })
            .ForeignKey("dbo.AspNetRoles", t => t.RoleId, cascadeDelete: true)
            .ForeignKey("dbo.AspNetUsers", t => t.UserId, cascadeDelete: true)
            .Index(t => t.UserId)
            .Index(t => t.RoleId);

        CreateTable(
            "dbo.AspNetUsers",
            c => new
                {
                    Id = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    Email = c.String(maxLength: 256, storeType: "nvarchar"),
                    EmailConfirmed = c.Boolean(nullable: false),
                    PasswordHash = c.String(maxLength: 256, storeType: "nvarchar"),
                    SecurityStamp = c.String(maxLength: 256, storeType: "nvarchar"),
                    PhoneNumber = c.String(maxLength: 256, storeType: "nvarchar"),
                    PhoneNumberConfirmed = c.Boolean(nullable: false),
                    TwoFactorEnabled = c.Boolean(nullable: false),
                    LockoutEndDateUtc = c.DateTime(precision: 0),
                    LockoutEnabled = c.Boolean(nullable: false),
                    AccessFailedCount = c.Int(nullable: false),
                    UserName = c.String(nullable: false, maxLength: 256, storeType: "nvarchar"),
                })
            .PrimaryKey(t => t.Id)
            .Index(t => t.UserName, unique: true, name: "UserNameIndex");

        CreateTable(
            "dbo.AspNetUserClaims",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    UserId = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    ClaimType = c.String(maxLength: 256, storeType: "nvarchar"),
                    ClaimValue = c.String(maxLength: 256, storeType: "nvarchar"),
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("dbo.AspNetUsers", t => t.UserId, cascadeDelete: true)
            .Index(t => t.UserId);

        CreateTable(
            "dbo.AspNetUserLogins",
            c => new
                {
                    LoginProvider = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    ProviderKey = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    UserId = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                })
            .PrimaryKey(t => new { t.LoginProvider, t.ProviderKey, t.UserId })
            .ForeignKey("dbo.AspNetUsers", t => t.UserId, cascadeDelete: true)
            .Index(t => t.UserId);

    }

    public override void Down()
    {
        DropForeignKey("dbo.AspNetUserRoles", "UserId", "dbo.AspNetUsers");
        DropForeignKey("dbo.AspNetUserLogins", "UserId", "dbo.AspNetUsers");
        DropForeignKey("dbo.AspNetUserClaims", "UserId", "dbo.AspNetUsers");
        DropForeignKey("dbo.AspNetUserRoles", "RoleId", "dbo.AspNetRoles");
        DropIndex("dbo.AspNetUserLogins", new[] { "UserId" });
        DropIndex("dbo.AspNetUserClaims", new[] { "UserId" });
        DropIndex("dbo.AspNetUsers", "UserNameIndex");
        DropIndex("dbo.AspNetUserRoles", new[] { "RoleId" });
        DropIndex("dbo.AspNetUserRoles", new[] { "UserId" });
        DropIndex("dbo.AspNetRoles", "RoleNameIndex");
        DropTable("dbo.AspNetUserLogins");
        DropTable("dbo.AspNetUserClaims");
        DropTable("dbo.AspNetUsers");
        DropTable("dbo.AspNetUserRoles");
        DropTable("dbo.AspNetRoles");
    }

当我使用 Microsoft.AspNet.Identity.EntityFramework 的 1.0.0.0 版本时，更新数据库的代码不同，我没有遇到任何问题

public override void Up()
    {
        CreateTable(
            "dbo.AspNetRoles",
            c => new
                {
                    Id = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    Name = c.String(nullable: false, maxLength: 256, storeType: "nvarchar"),
                })
            .PrimaryKey(t => t.Id);

        CreateTable(
            "dbo.AspNetUsers",
            c => new
                {
                    Id = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    UserName = c.String(maxLength: 256, storeType: "nvarchar"),
                    PasswordHash = c.String(maxLength: 256, storeType: "nvarchar"),
                    SecurityStamp = c.String(maxLength: 256, storeType: "nvarchar"),
                    Discriminator = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                })
            .PrimaryKey(t => t.Id);

        CreateTable(
            "dbo.AspNetUserClaims",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    ClaimType = c.String(maxLength: 256, storeType: "nvarchar"),
                    ClaimValue = c.String(maxLength: 256, storeType: "nvarchar"),
                    User_Id = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("dbo.AspNetUsers", t => t.User_Id, cascadeDelete: true)
            .Index(t => t.User_Id);

        CreateTable(
            "dbo.AspNetUserLogins",
            c => new
                {
                    UserId = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    LoginProvider = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    ProviderKey = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                })
            .PrimaryKey(t => new { t.UserId, t.LoginProvider, t.ProviderKey })
            .ForeignKey("dbo.AspNetUsers", t => t.UserId, cascadeDelete: true)
            .Index(t => t.UserId);

        CreateTable(
            "dbo.AspNetUserRoles",
            c => new
                {
                    UserId = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                    RoleId = c.String(nullable: false, maxLength: 128, storeType: "nvarchar"),
                })
            .PrimaryKey(t => new { t.UserId, t.RoleId })
            .ForeignKey("dbo.AspNetRoles", t => t.RoleId, cascadeDelete: true)
            .ForeignKey("dbo.AspNetUsers", t => t.UserId, cascadeDelete: true)
            .Index(t => t.UserId)
            .Index(t => t.RoleId);

    }



    public override void Down()
    {
        DropForeignKey("dbo.AspNetUserRoles", "UserId", "dbo.AspNetUsers");
        DropForeignKey("dbo.AspNetUserLogins", "UserId", "dbo.AspNetUsers");
        DropForeignKey("dbo.AspNetUserClaims", "UserId", "dbo.AspNetUsers");
        DropForeignKey("dbo.AspNetUserRoles", "RoleId", "dbo.AspNetRoles");
        DropIndex("dbo.AspNetUserLogins", new[] { "UserId" });
        DropIndex("dbo.AspNetUserClaims", new[] { "UserId" });
        DropIndex("dbo.AspNetUsers", "UserNameIndex");
        DropIndex("dbo.AspNetUserRoles", new[] { "RoleId" });
        DropIndex("dbo.AspNetUserRoles", new[] { "UserId" });
        DropIndex("dbo.AspNetRoles", "RoleNameIndex");
        DropTable("dbo.AspNetUserLogins");
        DropTable("dbo.AspNetUserClaims");
        DropTable("dbo.AspNetUsers");
        DropTable("dbo.AspNetUserRoles");
        DropTable("dbo.AspNetRoles");
    }

谁能帮我解决这个问题？

提前致谢!

最佳答案

我知道这是一篇旧帖子，但我今天遇到了同样的问题并对此进行了一些调查，并想分享我的发现和解决方案。

问题是 Microsoft 在版本之间向 AspNetRoles 的 Name 列添加了一个唯一索引，并且由于该列的大小为 256，因此它违反了索引规则MySql 的。 AspNetUsers 上的 Name 列也会出现此问题。

所以，我去分析了怎么解决这个问题，我认为最正确的做法是减少 Name 列的长度(恕我直言，真的没有任何理由有一个名称那么长的角色/用户)。

在调查了 IdentityDbContext(基类)上的代码后，我认为解决这个问题最正确的方法是覆盖 ApplicationDbContext 中的 OnModelCreating 并调整那里的列大小是这样的:

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    //... default code for ApplicationDbContext

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        if (modelBuilder == null)
        {
            throw new ArgumentNullException("modelBuilder");
        }

        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<ApplicationUser>().Property(u => u.UserName).HasMaxLength(128);

        //Uncomment this to have Email length 128 too (not neccessary)
        //modelBuilder.Entity<ApplicationUser>().Property(u => u.Email).HasMaxLength(128);

        modelBuilder.Entity<IdentityRole>().Property(r => r.Name).HasMaxLength(128);
    }
}

此代码将使用 base.OnModelCreating 调用使用默认配置初始化身份模型，然后用我们自己的设置覆盖在基类中完成的设置。

由于您正在创建一个迁移项目，因此您需要重新运行迁移创建以获取更新的模型(或手动修改您的模型以调整列大小)。

这将解决问题，您将拥有 Asp.NET Identity 系统的全部功能。

当然，为了在创建项目时不出现任何错误，您可以只修改您的迁移代码，但是您将与您的上下文定义的模型有所不同，这并不好并且可能会导致问题。

关于c# - 身份 Entity Framework 库 - 更新数据库 [MySQL]，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23562585/