用户 table 不是使用 Entity Framework Core 3.1 在 MySql 数据库中创建的（代码优先方法）

Question

如何使用 Code First 方法和 Entity Framework Core 3.1 在 MySql 数据库中创建用户 table？

"DataAccessMySqlProvider": "server=localhost;database=jahan_alpha;uid=xxxx;password=xxxx" in appsettings.json

并且在 startup.cs 中：

public void ConfigureServices(IServiceCollection services)
{
   services.AddDbContext<ApplicationDbContext>(options =>
            options.UseMySQL(Configuration["ConnectionStrings:DataAccessMySqlProvider"],
            b => b.MigrationsAssembly("Alpha.DataAccess")));
   // .UseMySQL is in Microsoft.EntityFrameworkCore namespace
}

I 运行 Add-Migration Init-MySql-database 然后 Update-database 在程序包管理器控制台中。这样做之后，我得到了这个错误：

PM> Update-Database Build started... Build succeeded.
Microsoft.EntityFrameworkCore.Infrastructure[10403]
      Entity Framework Core 3.1.3 initialized 'ApplicationDbContext' using provider 'Pomelo.EntityFrameworkCore.MySql' with options:
MigrationsAssembly=Alpha.DataAccess 
Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (1,299ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      CREATE DATABASE `jahan_alpha`; Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (9,281ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      CREATE TABLE `__EFMigrationsHistory` (
          `MigrationId` varchar(95) NOT NULL,
          `ProductVersion` varchar(32) NOT NULL,
          CONSTRAINT `PK___EFMigrationsHistory` PRIMARY KEY (`MigrationId`)
      ); Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (118ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='jahan_alpha' AND TABLE_NAME='__EFMigrationsHistory';
Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (5ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT `MigrationId`, `ProductVersion`
      FROM `__EFMigrationsHistory`
      ORDER BY `MigrationId`; Microsoft.EntityFrameworkCore.Migrations[20402]
      Applying migration '20200515231101_Init-MySql'. Applying migration '20200515231101_Init-MySql'. fail:
Microsoft.EntityFrameworkCore.Database.Command[20102]
      Failed executing DbCommand (181ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      ALTER TABLE `User` DROP INDEX `UserNameIndex`; Failed executing DbCommand (181ms) [Parameters=[], CommandType='Text',
CommandTimeout='30'] ALTER TABLE `User` DROP INDEX `UserNameIndex`;
MySql.Data.MySqlClient.MySqlException (0x80004005): Table
'jahan_alpha.user' doesn't exist  --->
MySql.Data.MySqlClient.MySqlException (0x80004005): Table
'jahan_alpha.user' doesn't exist
    at MySqlConnector.Core.ResultSet.ReadResultSetHeaderAsync(IOBehavior ioBehavior) in C:\projects\mysqlconnector\src\MySqlConnector\Core\ResultSet.cs:line 49
    at MySql.Data.MySqlClient.MySqlDataReader.ActivateResultSet() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlDataReader.cs:line 130
    at MySql.Data.MySqlClient.MySqlDataReader.CreateAsync(CommandListPosition commandListPosition, ICommandPayloadCreator payloadCreator, IDictionary`2 cachedProcedures, IMySqlCommand command, CommandBehavior behavior, IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlDataReader.cs:line 391
    at MySqlConnector.Core.CommandExecutor.ExecuteReaderAsync(IReadOnlyList`1 commands, ICommandPayloadCreator payloadCreator, CommandBehavior behavior, IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\Core\CommandExecutor.cs:line 62
    at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQueryAsync(IOBehavior ioBehavior, CancellationToken cancellationToken) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 226
    at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 74
    at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteNonQuery(RelationalCommandParameterObject parameterObject)
    at Microsoft.EntityFrameworkCore.Migrations.MigrationCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues)
    at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1 migrationCommands, IRelationalConnection connection)
    at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
    at Pomelo.EntityFrameworkCore.MySql.Migrations.Internal.MySqlMigrator.Migrate(String targetMigration)
    at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType)
    at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String targetMigration, String contextType)
    at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
    at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Table 'jahan_alpha.user' doesn't exist

ApplicationDbContext:

namespace Alpha.DataAccess
{
    public class ApplicationDbContext : IdentityDbContext<User, Role, int, UserClaim, UserRole, UserLogin, RoleClaim, UserToken>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
        {

        }
        // some codes...

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            // it should be placed here, otherwise it will rewrite the following settings!
            base.OnModelCreating(modelBuilder);

            modelBuilder.Entity<RoleClaim>(builder =>
            {
                builder.HasOne(roleClaim => roleClaim.Role).WithMany(role => role.Claims).HasForeignKey(roleClaim => roleClaim.RoleId);
                builder.ToTable("RoleClaim");
            });
            modelBuilder.Entity<Role>(builder =>
            {
                builder.ToTable("Role");
            });
            modelBuilder.Entity<UserClaim>(builder =>
            {
                builder.HasOne(userClaim => userClaim.User).WithMany(user => user.Claims).HasForeignKey(userClaim => userClaim.UserId);
                builder.ToTable("UserClaim");
            });
            modelBuilder.Entity<UserLogin>(builder =>
            {
                builder.HasOne(userLogin => userLogin.User).WithMany(user => user.Logins).HasForeignKey(userLogin => userLogin.UserId);
                builder.ToTable("UserLogin");
            });

            modelBuilder.Entity<User>(builder =>
            {
                builder.ToTable("User"); //.HasMany(e => e.Comments).WithOne().OnDelete(DeleteBehavior.Cascade);
            });
            modelBuilder.Entity<UserRole>(builder =>
            {
                builder.HasOne(userRole => userRole.Role).WithMany(role => role.Users).HasForeignKey(userRole => userRole.RoleId);
                builder.HasOne(userRole => userRole.User).WithMany(user => user.Roles).HasForeignKey(userRole => userRole.UserId);
                builder.ToTable("UserRole");
            });
            modelBuilder.Entity<UserToken>(builder =>
            {
                builder.HasOne(userToken => userToken.User).WithMany(user => user.UserTokens).HasForeignKey(userToken => userToken.UserId);
                builder.ToTable("UserToken");
            });

            // some codes...
        }

        public static async Task CreateAdminAccount(IServiceProvider serviceProvider, IConfiguration configuration)
        {
            UserManager<User> userManager = serviceProvider.GetRequiredService<UserManager<User>>();
            RoleManager<Role> roleManager = serviceProvider.GetRequiredService<RoleManager<Role>>();

            string userName = configuration["Data:AdminUser:Name"];
            string email = configuration["Data:AdminUser:Email"];
            string password = configuration["Data:AdminUser:Password"];
            string role = configuration["Data:AdminUser:Role"];

            if (await userManager.FindByNameAsync(userName) == null)
            {
                if (await roleManager.FindByNameAsync(role) == null)
                {
                    await roleManager.CreateAsync(new Role(role));
                }

                User user = new User
                {
                    Email = email,
                    UserName = userName
                };
                var result = userManager.CreateAsync(user, password);
                if (result.IsCompletedSuccessfully)
                {
                    await userManager.AddToRoleAsync(user, role);
                }
            }
        }
    }
}

Answer 1

基于执行的第一个命令是 ALTER DATABASE 这一事实，我假设 1) 当您生成初始命令时，您已经有一个带有 table User 的手动生成的数据库迁移和 2) 然后你删除了数据库 3) 然后你运行 Update-Database 命令。

将迁移视为将数据库从一个 table 状态移动到另一个状态的增量补丁。如果你想在更新数据库时看到实际的 SQL 会是运行，你可以发出 dotnet ef migrations script -i -o migrations.sql 命令。这将生成一个完整的脚本，其中包含从初始状态到当前状态的所有迁移。

我进一步假设您在隐藏的 // some codes... 代码块 // some codes... 某处的 ApplicationDbContext 中实际上有一个 DbSet<User> 属性

正如评论中已经指出的那样，您需要做的是；

从服务器 localhost 删除 jahan_alpha 数据库
从您的项目中完全删除 Migrations 文件夹
运行 dotnet ef migrations add initial
运行 dotnet ef migrations script -i -o migrations.sql
验证 migrations.sql 文件中的 SQL 命令是否正确（例如 CREATE DATABASE 在 ALTER DATABASE 的任何实例之前）
现在运行 dotnet ef database update - 这将生成 jahan_alpha 数据库，其中包含代码优先项目中定义的模式

用户 table 不是使用 Entity Framework Core 3.1 在 MySql 数据库中创建的（代码优先方法）

The User table is not created in MySql database using Entity Framework Core 3.1 (Code-first approach )

mysql-workbench

ef-code-first

entity-framework-core

asp.net-core

asp.net-core-3.1