EF Core Migration 重新创建重命名的表答案

【问题标题】：EF Core Migration recreates renamed tablesEF Core Migration 重新创建重命名的表
【发布时间】：2021-04-04 04:40:24
【问题描述】：

我正在使用 .NET 5 Identity 包并将其重命名为表，并使用了 IdentityUser 的扩展名。现在我决定向我的User 添加一些属性并应用迁移，但迁移尝试重新创建我重命名的表。

这是我的用户模型：

public class User : IdentityUser<int>, IUser
{
    public string Password { get; set; }

    public string Username { get => base.UserName; set => base.UserName = value; }
    public string Name { get; set; }

    public bool PubliclyVisible { get; set; } //New
    public IEnumerable<User> Trackers { get; set; } //New
    public IEnumerable<User> Tracked { get; set; } //New

}

我的DbContext扩展模型配置：

protected override void OnModelCreating(ModelBuilder modelBuilder)
{

    base.OnModelCreating(modelBuilder);
    modelBuilder.Entity<User>(b =>
    {
        b.ToTable("Users");
        b.HasMany(b => b.Tracked); //New
        b.HasMany(b => b.Trackers); //New 
        b.Ignore(u => u.Username);
                
    });

    modelBuilder.Entity<GPSData>().HasOne(d => d.User);

    modelBuilder.Entity<IdentityUserClaim<int>>(b => b.ToTable("UserClaims"));
    modelBuilder.Entity<IdentityUserLogin<int>>(b => b.ToTable("UserLogins"));
    modelBuilder.Entity<IdentityUserToken<int>>(b => b.ToTable("UserTokens"));
    modelBuilder.Entity<IdentityRole>(b => b.ToTable("Roles"));
    modelBuilder.Entity<IdentityRoleClaim<int>>(b => b.ToTable("RoleClaims"));
    modelBuilder.Entity<IdentityUserRole<int>>(b => b.ToTable("UserRoles"));

}

我将User 中的新属性以及配置中的其他行标记为//New。

在我运行add-migration AddedTrackingProperties之后

我得到以下迁移尝试重新创建我的表，因此当我更新表时，我得到一个错误 AspNetUserRoles 已经存在。

迁移配置

public partial class AddedTrackingProperties : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.CreateTable(
            name: "AspNetRoles",
            columns: table => new
            {
                Id = table.Column<int>(type: "int", nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                Name = table.Column<string>(type: "nvarchar(256)", maxLength: 256, nullable: true),
                NormalizedName = table.Column<string>(type: "nvarchar(256)", maxLength: 256, nullable: true),
                ConcurrencyStamp = table.Column<string>(type: "nvarchar(max)", nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_AspNetRoles", x => x.Id);
            });

        migrationBuilder.CreateTable(
            name: "Roles",
            columns: table => new
            {
                Id = table.Column<string>(type: "nvarchar(450)", nullable: false),
                Name = table.Column<string>(type: "nvarchar(max)", nullable: true),
                NormalizedName = table.Column<string>(type: "nvarchar(max)", nullable: true),
                ConcurrencyStamp = table.Column<string>(type: "nvarchar(max)", nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_Roles", x => x.Id);
            });

        migrationBuilder.CreateTable(
            name: "Users",
            columns: table => new
            {
                Id = table.Column<int>(type: "int", nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                Password = table.Column<string>(type: "nvarchar(max)", nullable: true),
                Name = table.Column<string>(type: "nvarchar(max)", nullable: true),
                PubliclyVisible = table.Column<bool>(type: "bit", nullable: false),
                UserName = table.Column<string>(type: "nvarchar(256)", maxLength: 256, nullable: true),
                NormalizedUserName = table.Column<string>(type: "nvarchar(256)", maxLength: 256, nullable: true),
                Email = table.Column<string>(type: "nvarchar(256)", maxLength: 256, nullable: true),
                NormalizedEmail = table.Column<string>(type: "nvarchar(256)", maxLength: 256, nullable: true),
                EmailConfirmed = table.Column<bool>(type: "bit", nullable: false),
                PasswordHash = table.Column<string>(type: "nvarchar(max)", nullable: true),
                SecurityStamp = table.Column<string>(type: "nvarchar(max)", nullable: true),
                ConcurrencyStamp = table.Column<string>(type: "nvarchar(max)", nullable: true),
                PhoneNumber = table.Column<string>(type: "nvarchar(max)", nullable: true),
                PhoneNumberConfirmed = table.Column<bool>(type: "bit", nullable: false),
                TwoFactorEnabled = table.Column<bool>(type: "bit", nullable: false),
                LockoutEnd = table.Column<DateTimeOffset>(type: "datetimeoffset", nullable: true),
                LockoutEnabled = table.Column<bool>(type: "bit", nullable: false),
                AccessFailedCount = table.Column<int>(type: "int", nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_Users", x => x.Id);
            });

        migrationBuilder.CreateTable(
            name: "RoleClaims",
            columns: table => new
            {
                Id = table.Column<int>(type: "int", nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                RoleId = table.Column<int>(type: "int", nullable: false),
                ClaimType = table.Column<string>(type: "nvarchar(max)", nullable: true),
                ClaimValue = table.Column<string>(type: "nvarchar(max)", nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_RoleClaims", x => x.Id);
                table.ForeignKey(
                    name: "FK_RoleClaims_AspNetRoles_RoleId",
                    column: x => x.RoleId,
                    principalTable: "AspNetRoles",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
            });

        migrationBuilder.CreateTable(
            name: "GPSData",
            columns: table => new
            {
                Id = table.Column<int>(type: "int", nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                Longitude = table.Column<double>(type: "float", nullable: false),
                Latitude = table.Column<double>(type: "float", nullable: false),
                Speed = table.Column<double>(type: "float", nullable: false),
                Timestamp = table.Column<DateTime>(type: "datetime2", nullable: false),
                UserId = table.Column<int>(type: "int", nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_GPSData", x => x.Id);
                table.ForeignKey(
                    name: "FK_GPSData_Users_UserId",
                    column: x => x.UserId,
                    principalTable: "Users",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
            });

        migrationBuilder.CreateTable(
            name: "UserClaims",
            columns: table => new
            {
                Id = table.Column<int>(type: "int", nullable: false)
                    .Annotation("SqlServer:Identity", "1, 1"),
                UserId = table.Column<int>(type: "int", nullable: false),
                ClaimType = table.Column<string>(type: "nvarchar(max)", nullable: true),
                ClaimValue = table.Column<string>(type: "nvarchar(max)", nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_UserClaims", x => x.Id);
                table.ForeignKey(
                    name: "FK_UserClaims_Users_UserId",
                    column: x => x.UserId,
                    principalTable: "Users",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
            });

        migrationBuilder.CreateTable(
            name: "UserLogins",
            columns: table => new
            {
                LoginProvider = table.Column<string>(type: "nvarchar(450)", nullable: false),
                ProviderKey = table.Column<string>(type: "nvarchar(450)", nullable: false),
                ProviderDisplayName = table.Column<string>(type: "nvarchar(max)", nullable: true),
                UserId = table.Column<int>(type: "int", nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_UserLogins", x => new { x.LoginProvider, x.ProviderKey });
                table.ForeignKey(
                    name: "FK_UserLogins_Users_UserId",
                    column: x => x.UserId,
                    principalTable: "Users",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
            });

        migrationBuilder.CreateTable(
            name: "UserRoles",
            columns: table => new
            {
                UserId = table.Column<int>(type: "int", nullable: false),
                RoleId = table.Column<int>(type: "int", nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_UserRoles", x => new { x.UserId, x.RoleId });
                table.ForeignKey(
                    name: "FK_UserRoles_AspNetRoles_RoleId",
                    column: x => x.RoleId,
                    principalTable: "AspNetRoles",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
                table.ForeignKey(
                    name: "FK_UserRoles_Users_UserId",
                    column: x => x.UserId,
                    principalTable: "Users",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
            });

        migrationBuilder.CreateTable(
            name: "UserTokens",
            columns: table => new
            {
                UserId = table.Column<int>(type: "int", nullable: false),
                LoginProvider = table.Column<string>(type: "nvarchar(450)", nullable: false),
                Name = table.Column<string>(type: "nvarchar(450)", nullable: false),
                Value = table.Column<string>(type: "nvarchar(max)", nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_UserTokens", x => new { x.UserId, x.LoginProvider, x.Name });
                table.ForeignKey(
                    name: "FK_UserTokens_Users_UserId",
                    column: x => x.UserId,
                    principalTable: "Users",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
            });

        migrationBuilder.CreateTable(
            name: "UserUser",
            columns: table => new
            {
                TrackedId = table.Column<int>(type: "int", nullable: false),
                TrackersId = table.Column<int>(type: "int", nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_UserUser", x => new { x.TrackedId, x.TrackersId });
                table.ForeignKey(
                    name: "FK_UserUser_Users_TrackedId",
                    column: x => x.TrackedId,
                    principalTable: "Users",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
                table.ForeignKey(
                    name: "FK_UserUser_Users_TrackersId",
                    column: x => x.TrackersId,
                    principalTable: "Users",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Restrict);
            });

        migrationBuilder.CreateIndex(
            name: "RoleNameIndex",
            table: "AspNetRoles",
            column: "NormalizedName",
            unique: true,
            filter: "[NormalizedName] IS NOT NULL");

        migrationBuilder.CreateIndex(
            name: "IX_GPSData_UserId",
            table: "GPSData",
            column: "UserId");

        migrationBuilder.CreateIndex(
            name: "IX_RoleClaims_RoleId",
            table: "RoleClaims",
            column: "RoleId");

        migrationBuilder.CreateIndex(
            name: "IX_UserClaims_UserId",
            table: "UserClaims",
            column: "UserId");

        migrationBuilder.CreateIndex(
            name: "IX_UserLogins_UserId",
            table: "UserLogins",
            column: "UserId");

        migrationBuilder.CreateIndex(
            name: "IX_UserRoles_RoleId",
            table: "UserRoles",
            column: "RoleId");

        migrationBuilder.CreateIndex(
            name: "EmailIndex",
            table: "Users",
            column: "NormalizedEmail");

        migrationBuilder.CreateIndex(
            name: "UserNameIndex",
            table: "Users",
            column: "NormalizedUserName",
            unique: true,
            filter: "[NormalizedUserName] IS NOT NULL");

        migrationBuilder.CreateIndex(
            name: "IX_UserUser_TrackersId",
            table: "UserUser",
            column: "TrackersId");
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropTable(
            name: "GPSData");

        migrationBuilder.DropTable(
            name: "RoleClaims");

        migrationBuilder.DropTable(
            name: "Roles");

        migrationBuilder.DropTable(
            name: "UserClaims");

        migrationBuilder.DropTable(
            name: "UserLogins");

        migrationBuilder.DropTable(
            name: "UserRoles");

        migrationBuilder.DropTable(
            name: "UserTokens");

        migrationBuilder.DropTable(
            name: "UserUser");

        migrationBuilder.DropTable(
            name: "AspNetRoles");

        migrationBuilder.DropTable(
            name: "Users");
    }
}

那么错在哪里？

【问题讨论】：

你解决了吗？
@dglozano，抱歉回复晚了。是的，我非常了解这个问题，起初我认为 EF Core 以某种方式注册了早期的更改并相应地提供了迁移代码。但正如你所指出的，事实并非如此。

标签： .net entity-framework database-migration

【解决方案1】：

据我了解，Entity Framework 通常无法检测到您何时打算重命名列/表或实际删除它并创建其他内容，因此它最终构建了一个删除并重新创建列的迁移/表。

来自docs：

EF Core 通常无法知道何时打算删除列并创建新列（两个单独的更改），以及何时应重命名列。如果按原样应用上述迁移，您的所有客户名称都将丢失。要重命名列，请将上面生成的迁移替换为以下内容：

在这种情况下，您应该做的是自定义由 EF 自动构建的迁移代码。在这种情况下，您可以利用 RenameColumn 和 RenameTable 方法来指定在迁移中只应进行重命名操作。

因此，在生成迁移后，删除Up 和Down 方法中的Drop 和Create 语句，并将它们替换为对RenameTable 和RenameColumn 的相应调用。

例如：

public partial class AddedTrackingProperties : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.RenameTable(
            name: "IdentityUserRole", newName: "UserRoles");

       // ...
       // TODO: other necessary rename tables/columns
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.RenameTable(
            name: "UserRoles", newName: "IdentityUserRole");

       // ...
       // TODO: other necessary rename tables/columns
    }
}

【讨论】：