Question

无论如何，当您在Entity Framework Core中调用Add-Migration时，是否可以访问用于创建数据库迁移的方法？

如果这有所不同，则它在.NET Core 2.2项目中。

Answer 1

要访问Migration，可以实现MigrationsAssembly。

实施ColumnOrderMigrationAssembly

public class ColumnOrderMigrationAssembly : MigrationsAssembly
{
    private readonly DbContext _context;

    public ColumnOrderMigrationAssembly(ICurrentDbContext currentContext,
        IDbContextOptions options, IMigrationsIdGenerator idGenerator,
        IDiagnosticsLogger<DbLoggerCategory.Migrations> logger)
    : base(currentContext, options, idGenerator, logger)
    {
        _context = currentContext.Context;
    }

    public override Migration CreateMigration(TypeInfo migrationClass,
        string activeProvider)
    {
        var migration = base.CreateMigration(migrationClass, activeProvider);
        var productTableMigration = migration.UpOperations.FirstOrDefault(m => m.GetType() == typeof(CreateTableOperation) 
        && ((CreateTableOperation)m).Name == "Products") as CreateTableOperation;
        if (productTableMigration != null)
        {
            var columns =new List<AddColumnOperation>(productTableMigration.Columns.OrderBy(o => o.Name));
            productTableMigration.Columns.Clear();
            productTableMigration.Columns.AddRange(columns);
        }
        return migration;
    }
}

注册ColumnOrderMigrationAssembly

services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(
        Configuration.GetConnectionString("DefaultConnection"))
        .ReplaceService<IMigrationsAssembly, ColumnOrderMigrationAssembly>());

启用migrate

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider serviceProvider)
{
    //your rest code
    using (var db = serviceProvider.CreateScope().ServiceProvider.GetRequiredService<ApplicationDbContext>())
    {
        db.Database.Migrate();
    }
}

根据自己的需要更改CreateMigration中的逻辑。

Answer 2

在运行Add-Migration的项目下，有一个名为Migration的文件夹，在其中添加了Migration类。重新运行迁移时，您可以更改列的顺序。

生成迁移ef核心的访问方法

2 个答案: