使用ABP框架踩过的坑系列5

    DDD领域驱动开发,实际是为复杂的业务场景而生的,为了让开发人员专注于业务,而操作系统、数据库、网络之类的技术细节,必须要持久透明化:实际就是数据库系统DBMS的ORM抽象,目标就是业务不需要考虑数据是如何存储的,业务是独立于DBMS, 通俗讲业务系统不依赖某个DBMS实现,可以通过配置,灵活动态支持各种DBMS,如MS SQL、MySql、Orcacle等。ABP的目标是DDD, 在持久透明化这块,是用IRepository仓储抽象来做的,具体的DBMS实现的ORM就放在基础架构层Infrastructure里。理想是很美好的,实际还是有些坑的,我在做一个项目,当把MSSQL切换到MySql,还是遇到了问题!

 public static class DbContextConfigurer
    {
        public static void Configure(DbContextOptionsBuilder<DbContext> builder, string connectionString)
        {
            //builder.UseSqlServer(connectionString); //使用MSSQL
            builder
                //.UseLoggerFactory(MyLoggerFactory)
                .UseMySql(connectionString);  //使用MySql
        }

        public static void Configure(DbContextOptionsBuilder<DbContext> builder, DbConnection connection)
        {
            //builder.UseSqlServer(connection);
            builder.UseMySql(connection);
        }
    }

用ABP模板生成的项目中,如果使用.netcore和EFcore, 就会有DbContextConfigurer,只要安装了Microsoft.entityframeworkcore.mysql, 就可以使用UseMySql这个扩展方法,

 "ConnectionStrings": {
    //"Default": "Server=localhost; Database=Db3; Trusted_Connection=True;"
    "Default": "Server=localhost;port=3306;database=Db3;uid=root;password=root;character set=utf8;Old Guids=true"
  },

appsettings.json 里ConnectionStrings,也使用Mysql连接字符串,然后再PMC(程序包控制台)执行

update-dabase

 完成以上步骤,从MSSQL切换到了Mysql, 大功告成!理想是这样的,事实上也大部分可行,但会报一些莫名其妙的错误:约束错误!这些问题,一度让我很沮丧,甚至想放弃mysql, 迫于linux下装MSSQL的恐怖,还是坚持用mysql, 后在baidu的帮助下,找到了原因:Microsoft.entityframeworkcore.mysql 有问题,必须用melo.EntityFrameworkCore.MySql

然后再PMC(程序包控制台)执行

install-package Pomelo.EntityFrameworkCore.MySql

再执行update-dabase, 真的一切都好了,其实在ORM的抽象和实现方面,ABP都比较好的Module, 当家的是Microsoft的EF

Abp.EntityFrameWork.Common   //EF的公共部分
Abp.EntityFrameWork  //EF
Abp.EntityFrameWorkCore //EFCore

还有来自Java阵营的

Abp.NHibernate

还有几个比较流行的,

Abp.Dapper //据说性能是ef几十倍的Dapper
Abp.MongoDB //nosql,KV和文档数据库
Abp.MemoryDb //内存数据库,可用于单元测试,棒棒的

个人还是偏爱EF系列,特别是linux下用EFCore+Mysql, 是最佳组合,经过几个项目的实战,证明是个不错选择,可以放心使用!

ABP有关ORM的抽象机制,主要通过Repostitory和UnitOfWork来做的

namespace Abp.Domain.Repositories
{
    /// <summary>
    /// This interface is implemented by all repositories to ensure implementation of fixed methods. 说白了就是CRUD得封装
    /// </summary>
    /// <typeparam name="TEntity">Main Entity type this repository works on</typeparam>
    /// <typeparam name="TPrimaryKey">Primary key type of the entity</typeparam>
    public interface IRepository<TEntity, TPrimaryKey> : IRepository where TEntity : class, IEntity<TPrimaryKey>
    {
        #region Select/Get/Query
       ...#endregion

        #region Insert
       ...#endregion

        #region Update
       ...#endregion

        #region Delete
       ...#endregion

        #region Aggregates
        ...#endregion
    }
}
/// <summary>
    /// Defines a unit of work.
    /// This interface is internally used by ABP. 实际上就是数据库连接和事务的封装
    /// Use <see cref="IUnitOfWorkManager.Begin()"/> to start a new unit of work.
    /// </summary>
    public interface IUnitOfWork : IActiveUnitOfWork, IUnitOfWorkCompleteHandle
    {
        /// <summary>
        /// Unique id of this UOW.
        /// </summary>
        string Id { get; }

        /// <summary>
        /// Reference to the outer UOW if exists.
        /// </summary>
        IUnitOfWork Outer { get; set; }
        
        /// <summary>
        /// Begins the unit of work with given options.
        /// </summary>
        /// <param name="options">Unit of work options</param>
        void Begin(UnitOfWorkOptions options);

具体我们在Service中,只要用DI就可以注入了,其实现机理,以EFCore为例

/// <summary>
    /// This module is used to implement "Data Access Layer" in EntityFramework. 类似Mybatis的数据访问层,在ABP中叫基础架构
    /// </summary>
    [DependsOn(typeof(AbpKernelModule))]
    public class AbpEntityFrameworkCoreModule : AbpModule
    {
        。。。private void RegisterGenericRepositoriesAndMatchDbContexes()
        {
            var dbContextTypes =
                _typeFinder.Find(type =>
                    type.IsPublic &&
                    !type.IsAbstract &&
                    type.IsClass &&
                    typeof(AbpDbContext).IsAssignableFrom(type)
                    );

            if (dbContextTypes.IsNullOrEmpty())
            {
                Logger.Warn("No class found derived from AbpDbContext.");
                return;
            }

            using (var repositoryRegistrar = IocManager.ResolveAsDisposable<IEfCoreGenericRepositoryRegistrar>())
            {
                foreach (var dbContextType in dbContextTypes)
                {
                    Logger.Debug("Registering DbContext: " + dbContextType.AssemblyQualifiedName);
                    repositoryRegistrar.Object.RegisterForDbContext(dbContextType, IocManager);
                }
            }

           。。。
        }
    }
 public class EfCoreGenericRepositoryRegistrar : IEfCoreGenericRepositoryRegistrar, ITransientDependency
    {
       。。。public void RegisterForDbContext(Type dbContextType, IIocManager iocManager)
        {
            var autoRepositoryAttr = dbContextType.GetSingleAttributeOrNull<AutoRepositoryTypesAttribute>() ??
                                     EfCoreAutoRepositoryTypes.Default;

            foreach (var entityTypeInfo in DbContextHelper.GetEntityTypeInfos(dbContextType))
            {
                var primaryKeyType = EntityHelper.GetPrimaryKeyType(entityTypeInfo.EntityType);
                if (primaryKeyType == typeof(int))
                {
                    var genericRepositoryType = autoRepositoryAttr.RepositoryInterface.MakeGenericType(entityTypeInfo.EntityType);
                    if (!iocManager.IsRegistered(genericRepositoryType))
                    {
                        var implType = autoRepositoryAttr.RepositoryImplementation.GetGenericArguments().Length == 1
                                ? autoRepositoryAttr.RepositoryImplementation.MakeGenericType(entityTypeInfo.EntityType)
                                : autoRepositoryAttr.RepositoryImplementation.MakeGenericType(entityTypeInfo.DeclaringType, entityTypeInfo.EntityType);

                        iocManager.Register(
                            genericRepositoryType,
                            implType,
                            DependencyLifeStyle.Transient
                            );
                    }
                }

                var genericRepositoryTypeWithPrimaryKey = autoRepositoryAttr.RepositoryInterfaceWithPrimaryKey.MakeGenericType(entityTypeInfo.EntityType, primaryKeyType);
                if (!iocManager.IsRegistered(genericRepositoryTypeWithPrimaryKey))
                {
                    var implType = autoRepositoryAttr.RepositoryImplementationWithPrimaryKey.GetGenericArguments().Length == 2
                                ? autoRepositoryAttr.RepositoryImplementationWithPrimaryKey.MakeGenericType(entityTypeInfo.EntityType, primaryKeyType)
                                : autoRepositoryAttr.RepositoryImplementationWithPrimaryKey.MakeGenericType(entityTypeInfo.DeclaringType, entityTypeInfo.EntityType, primaryKeyType);

                    iocManager.Register(
                        genericRepositoryTypeWithPrimaryKey,
                        implType,
                        DependencyLifeStyle.Transient
                        );
                }
            }
        }
    }

整个目的就是为了可以注入泛型的IRepostitory<TEntity, TPrimaryKey>,我们的service,就可以愉快的使用了

public IRepository<FoodMaterial, long> FoodMaterialRepository { get; set; } //属性注入
//或
private IRepository<FoodMaterialCategory, long> _categoryRepository;
        public FoodMaterialAppService(IRepository<FoodMaterial, long> repository
                                    , IRepository<FoodMaterialCategory, long> categoryRepository) 
            : base(repository)
        {
            _categoryRepository = categoryRepository;
        } // 构造注入

 总结:.net 已经拥抱开源和linux了,曾经的四大金刚LAMP(Linux+Apache+Mysql+Php),如今.net也可以Cover了,跨平台(操作系统、数据库等),是一个上线系统的必须,特别部署到云上,linux+mysql的性价比还是比较高的,可真正要做到跨平台和持久透明,在设计DB时,还是要注意:不要用存储过程,所有逻辑必须在代码里完成,DB只是用来存储的;ABP在这个领域,给了我们OutOfBox开箱即用的很多Module, 可以让我们效率大大提升!

posted @ 2018-06-15 11:16 szdlsoft 阅读(...) 评论(...) 编辑 收藏