Question

我有一个现有的DbContext类，我想将其用作其他Web项目的基类。 DbContext包含一个真正完整的表结构，用于注册公司和人员以及相关信息。

开始一个新项目时，我不想一次又一次地创建相同的结构！所以我尝试重用现有的DbContext作为我的新项目的基类，只需添加新表来使其在新应用程序中按需运行。

但是，我找不到让它运转的方法！ DbContext基类如下所示，它来自另一个项目：

public class TemplateDbContext 
{       
        private readonly Guid _instanceId;
        bool _disposed;
        public Guid InstanceId { get { return _instanceId; } }
        public TemplateDbContext ()
            : base("name=" + GetConnectionStringName)
        {
        }

        public static TemplateDbContext  Create() 
        {
            return new TemplateDbContext ();
        }
        private void SetOneToMany(DbModelBuilder modelBuilder)
        {

        }

        private void SetManyToMany(DbModelBuilder modelBuilder)
        {

        }

        private void SetOneToOne(DbModelBuilder modelBuilder)
        {

        }

        private void SetOneNavigation(DbModelBuilder modelBuilder)
        {

        }

        private void SetKeys(DbModelBuilder modelBuilder)
        {

        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            modelBuilder.Entity<IdentityUserClaim>().ToTable("MembershipClaims");
            modelBuilder.Entity<IdentityUserRole>().ToTable("MembershipRoles");
            modelBuilder.Entity<IdentityUserLogin>().ToTable("MembershipLogins");
            modelBuilder.Entity<IdentityRole>().ToTable("Roles");
            modelBuilder.Entity<Membership>().ToTable("Memberships");

            SetKeys(modelBuilder);
            SetOneNavigation(modelBuilder);
            SetOneToOne(modelBuilder);
            SetOneToMany(modelBuilder);
            SetManyToMany(modelBuilder);
        }

        public static string GetConnectionStringName
        {
            get
            {
                ...
            }
        }

        public DbSet<UserProfile> UserProfiles
        {
            get;
            set;
        }

        // I have many more DbSet defined here...
        public override int SaveChanges()
        {
            ...
        }

        public override async Task<int> SaveChangesAsync()
        {
            ...
        }

        public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken)
        {
            ...
        }

        public void SyncObjectState<TEntity>(TEntity entity) where TEntity : class, IObjectState
        {
            ...
        }

        private void SyncObjectsStatePreCommit()
        {
            ...
        }

        public void SyncObjectsStatePostCommit()
        {
            ...
        }

        protected override void Dispose(bool disposing)
        {
            ...
        }
}

这是我的新项目的ApplicationDbContext：

public class ApplicationDbContext : TemplateDbContext 
    {
        public DbSet<Fruit> Fruits { get; set; }
        // I have many more DbSet define here...

        private void SetOneToMany(DbModelBuilder modelBuilder)
        {
           ...
        }

        private void SetManyToMany(DbModelBuilder modelBuilder)
        {
           ...
        }

        private void SetOneToOne(DbModelBuilder modelBuilder)
        {
            ...
        }

        private void SetOneNavigation(DbModelBuilder modelBuilder)
        {
           ...
        }

        private void SetKeys(DbModelBuilder modelBuilder)
        {
            ...
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            SetKeys(modelBuilder);
            SetOneNavigation(modelBuilder);
            SetOneToOne(modelBuilder);
            SetOneToMany(modelBuilder);
            SetManyToMany(modelBuilder);
        }
    }

你可以做客，但这根本不起作用，我不知道如何才能达到我想要的效果。我甚至不知道是否可以不复制TemplateDbContext类的所有代码。我现在完成的最好的事情，它只生成TemplateDbContext，通过在新项目中执行Add Manager Migration with Package Manager Console。因此迁移错过了定义到ApplicationDbContext类中的所有DbSet。

我需要做什么样的结构？

Answer 1

您可以在Context指定enable migration的名称，并以相同的方式使用其他命令，您可以找到更多信息about this here。

enable-migrations -ContextTypeName <DbContext-Name-with-Namespaces> -MigrationsDirectory:<Migrations-Directory-Name>
Add-Migration -configuration <DbContext-Migrations-Configuration-Class-with-Namespaces> <Migrations-Name>
Update-Database -configuration <DbContext-Migrations-Configuration-Class-with-Namespaces> -Verbose

注意：不要忘记将默认项目更改为程序包管理器控制台中的ApplicationDbContext。< / p>

另外我认为您在base.OnModelCreating(modelBuilder)覆盖方法时忘记拨打ApplicationDbContext。

如何将现有的DbContext重用为新项目的基类？

1 个答案: