ASP.Net Core基于EF6、Unitwork、Autofac實(shí)現(xiàn)Repository模式

更新時(shí)間：2022年02月16日 11:42:04 作者：Run2948

這篇文章介紹了ASP.Net Core基于EF6、Unitwork、Autofac實(shí)現(xiàn)Repository模式的方法，文中通過(guò)示例代碼介紹的非常詳細(xì)。對(duì)大家的學(xué)習(xí)或工作具有一定的參考借鑒價(jià)值，需要的朋友可以參考下

一、實(shí)現(xiàn)的思路和結(jié)構(gòu)圖

Repository的共同性

有一些公共的方法(增刪改查)，這些方法無(wú)關(guān)于Repository操作的是哪個(gè)實(shí)體類(lèi)，可以把這些方法定義成接口IRepository，然后有個(gè)基類(lèi)BaseRepository實(shí)現(xiàn)該接口的方法。常見(jiàn)的方法，比如Find, Filter, Delete, Create等

Repository的差異性

每個(gè)Repository類(lèi)又會(huì)有一些差異性，應(yīng)當(dāng)允許它們能夠繼承BaseRepository之外，還能夠再擴(kuò)展自己的一些方法。所以每個(gè)類(lèi)都可以再定義一個(gè)自己特有的接口，定義一些屬于自己Repository的方法。

Repository的協(xié)同性

不同的Repository可能需要協(xié)同，Repository對(duì)數(shù)據(jù)的修改，需要在統(tǒng)一的保存.
最終實(shí)現(xiàn)的類(lèi)結(jié)構(gòu)圖如下:

類(lèi)結(jié)構(gòu)圖

二、Repository設(shè)計(jì)具體的實(shí)現(xiàn)代碼

IRepository接口定義了Repository共有的方法, BaseRepository實(shí)現(xiàn)了這些接口的方法。其它的Repository類(lèi)再集成BaseRepository方法，就天然的得到了對(duì)數(shù)據(jù)操作的基本方法。

IRepository代碼

    public interface IRepository<TEntity> where TEntity : class
    {
        /// <summary>
        /// Gets all objects from database
        /// </summary>
        /// <returns></returns>
        IQueryable<TEntity> All();

        /// <summary>
        /// Gets objects from database by filter.
        /// </summary>
        /// <param name="predicate">Specified a filter</param>
        /// <returns></returns>
        IQueryable<TEntity> Filter(Expression<Func<TEntity, bool>> predicate);

        /// <summary>
        /// Gets objects from database with filtering and paging.
        /// </summary>
        /// <param name="filter">Specified a filter</param>
        /// <param name="total">Returns the total records count of the filter.</param>
        /// <param name="index">Specified the page index.</param>
        /// <param name="size">Specified the page size</param>
        /// <returns></returns>
        IQueryable<TEntity> Filter(Expression<Func<TEntity, bool>> filter, out int total, int index = 0, int size = 50);

        /// <summary>
        /// Gets the object(s) is exists in database by specified filter.
        /// </summary>
        /// <param name="predicate">Specified the filter expression</param>
        /// <returns></returns>
        bool Contains(Expression<Func<TEntity, bool>> predicate);

        /// <summary>
        /// Find object by keys.
        /// </summary>
        /// <param name="keys">Specified the search keys.</param>
        /// <returns></returns>
        TEntity Find(params object[] keys);

        /// <summary>
        /// Find object by specified expression.
        /// </summary>
        /// <param name="predicate"></param>
        /// <returns></returns>
        TEntity Find(Expression<Func<TEntity, bool>> predicate);

        /// <summary>
        /// Create a new object to database.
        /// </summary>
        /// <param name="t">Specified a new object to create.</param>
        /// <returns></returns>
        void Create(TEntity t);

        /// <summary>
        /// Delete the object from database.
        /// </summary>
        /// <param name="t">Specified a existing object to delete.</param>
        void Delete(TEntity t);

        /// <summary>
        /// Delete objects from database by specified filter expression.
        /// </summary>
        /// <param name="predicate"></param>
        /// <returns></returns>
        int Delete(Expression<Func<TEntity, bool>> predicate);

        /// <summary>
        /// Update object changes and save to database.
        /// </summary>
        /// <param name="t">Specified the object to save.</param>
        /// <returns></returns>
        void Update(TEntity t);

        /// <summary>
        /// Select Single Item by specified expression.
        /// </summary>
        /// <param name="expression"></param>
        /// <returns></returns>
        TEntity FirstOrDefault(Expression<Func<TEntity, bool>> expression);
    }

BaseRepository代碼

    public class BaseRepository<TEntity> : IRepository<TEntity> where TEntity : class
    {
        protected readonly DbContext Context;

        public BaseRepository(DbContext context)
        {
            Context = context;
        }

        /// <summary>
        /// Gets all objects from database
        /// </summary>
        /// <returns></returns>
        public IQueryable<TEntity> All()
        {
            return Context.Set<TEntity>().AsQueryable();
        }

        /// <summary>
        /// Gets objects from database by filter.
        /// </summary>
        /// <param name="predicate">Specified a filter</param>
        /// <returns></returns>
        public virtual IQueryable<TEntity> Filter(Expression<Func<TEntity, bool>> predicate)
        {
            return Context.Set<TEntity>().Where<TEntity>(predicate).AsQueryable<TEntity>();
        }

        /// <summary>
        /// Gets objects from database with filtering and paging.
        /// </summary>
        /// <param name="filter">Specified a filter</param>
        /// <param name="total">Returns the total records count of the filter.</param>
        /// <param name="index">Specified the page index.</param>
        /// <param name="size">Specified the page size</param>
        /// <returns></returns>
        public virtual IQueryable<TEntity> Filter(Expression<Func<TEntity, bool>> filter, out int total, int index = 0,
            int size = 50)
        {
            var skipCount = index * size;
            var resetSet = filter != null
                ? Context.Set<TEntity>().Where<TEntity>(filter).AsQueryable()
                : Context.Set<TEntity>().AsQueryable();
            resetSet = skipCount == 0 ? resetSet.Take(size) : resetSet.Skip(skipCount).Take(size);
            total = resetSet.Count();
            return resetSet.AsQueryable();
        }

        /// <summary>
        /// Gets the object(s) is exists in database by specified filter.
        /// </summary>
        /// <param name="predicate">Specified the filter expression</param>
        /// <returns></returns>
        public bool Contains(Expression<Func<TEntity, bool>> predicate)
        {
            return Context.Set<TEntity>().Any(predicate);
        }

        /// <summary>
        /// Find object by keys.
        /// </summary>
        /// <param name="keys">Specified the search keys.</param>
        /// <returns></returns>
        public virtual TEntity Find(params object[] keys)
        {
            return Context.Set<TEntity>().Find(keys);
        }

        /// <summary>
        /// Find object by specified expression.
        /// </summary>
        /// <param name="predicate"></param>
        /// <returns></returns>
        public virtual TEntity Find(Expression<Func<TEntity, bool>> predicate)
        {
            return Context.Set<TEntity>().FirstOrDefault<TEntity>(predicate);
        }

        /// <summary>
        /// Create a new object to database.
        /// </summary>
        /// <param name="t">Specified a new object to create.</param>
        /// <returns></returns>
        public virtual void Create(TEntity t)
        {
            Context.Set<TEntity>().Add(t);
        }

        /// <summary>
        /// Delete the object from database.
        /// </summary>
        /// <param name="t">Specified a existing object to delete.</param>
        public virtual void Delete(TEntity t)
        {
            Context.Set<TEntity>().Remove(t);
        }

        /// <summary>
        /// Delete objects from database by specified filter expression.
        /// </summary>
        /// <param name="predicate"></param>
        /// <returns></returns>
        public virtual int Delete(Expression<Func<TEntity, bool>> predicate)
        {
            var objects = Filter(predicate);
            foreach (var obj in objects)
                Context.Set<TEntity>().Remove(obj);
            return Context.SaveChanges();
        }

        /// <summary>
        /// Update object changes and save to database.
        /// </summary>
        /// <param name="t">Specified the object to save.</param>
        /// <returns></returns>
        public virtual void Update(TEntity t)
        {
            try
            {
                var entry = Context.Entry(t);
                Context.Set<TEntity>().Attach(t);
                entry.State = EntityState.Modified;
            }
            catch (OptimisticConcurrencyException ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// Select Single Item by specified expression.
        /// </summary>
        /// <param name="expression"></param>
        /// <returns></returns>
        public TEntity FirstOrDefault(Expression<Func<TEntity, bool>> expression)
        {
            return All().FirstOrDefault(expression);
        }
    }

IUnitOfWork接口定義了方法獲取特定的Repository, 執(zhí)行存儲(chǔ)過(guò)程, SaveChange方法提交修改，統(tǒng)一更新數(shù)據(jù)。

IUnitOfWork接口代碼:

    public interface IUnitOfWork : IDisposable
    {
        DbContext DbContext { get; }
        TRepository GetRepository<TRepository>() where TRepository : class;
        void ExecuteProcedure(string procedureCommand, params object[] sqlParams);
        void ExecuteSql(string sql);
        List<T> SqlQuery<T>(string sql);
        void SaveChanges();
    }

UnitOfWork代碼, 代碼中使用到了Autofac中的IComponentContext來(lái)獲取Repository實(shí)例

    public class UnitOfWork : IUnitOfWork
    {
        private readonly IComponentContext _componentContext;
        protected readonly DbContext Context;

        public UnitOfWork(DbContext context, IComponentContext componentContext)
        {
            Context = context;
            _componentContext = componentContext;
        }

        public DbContext DbContext => Context;

        public TRepository GetRepository<TRepository>() where TRepository : class
        {
            return _componentContext.Resolve<TRepository>();
        }

        public void ExecuteProcedure(string procedureCommand, params object[] sqlParams)
        {
            Context.Database.ExecuteSqlCommand(procedureCommand, sqlParams);
        }

        public void ExecuteSql(string sql)
        {
            Context.Database.ExecuteSqlCommand(sql);
        }

        public List<T> SqlQuery<T>(string sql)
        {
            return Context.Database.SqlQuery<T>(sql).ToList();
        }

        public void SaveChanges()
        {
            try
            {
                Context.SaveChanges();
            }
            catch (InvalidOperationException ex)
            {
                if (!ex.Message.Contains("The changes to the database were committed successfully"))
                {
                    throw;
                }
            }
        }

        public void Dispose()
        {
            Context?.Dispose();
        }
    }

三、Repository設(shè)計(jì)的具體的使用

這里我們定義一個(gè)IStudentRepository接口, 包含了方法GetAllStudents(), 同時(shí)繼承于IRepository<Student>接口

public interface IStudentRepository : IRepository<Student>
{
    IEnumerable<dynamic> GetAllStudents();
}

接著定義StudentRepository類(lèi)來(lái)實(shí)現(xiàn)這個(gè)接口

public class StudentRepository : BaseRepository<Student>, IStudentRepository
{
    private readonly SchoolContext _context;

    public StudentRepository(SchoolContext context)
        : base(context)
    {
        _context = context;
    }

    public IEnumerable<dynamic> GetAllStudents()
    {
        return _context.Students;
    }
}

在Application_Start方法中使用Autofac注冊(cè)Repository的代碼如下：

    var builder = new ContainerBuilder();

    //register controllers
    builder.RegisterControllers(typeof(MvcApplication).Assembly);

    //register repository
    builder.RegisterAssemblyTypes(Assembly.GetExecutingAssembly()).AsImplementedInterfaces();

    //add the Entity Framework context to make sure only one context per request
    builder.RegisterType<SchoolContext>().InstancePerRequest();
    builder.Register(c => c.Resolve<SchoolContext>()).As<DbContext>().InstancePerRequest();

    var container = builder.Build();
    DependencyResolver.SetResolver(new AutofacDependencyResolver(container));

在控制器中注入使用Repository的代碼如下:

private readonly IUnitOfWork _repositoryCenter;

private readonly IStudentRepository _studentRepository;

public HomeController(IUnitOfWork repositoryCenter)
{
    _repositoryCenter = repositoryCenter;
    _studentRepository = _repositoryCenter.GetRepository<IStudentRepository>();
}

public ActionResult Index(Student sessionStudent)
{
    var students = _studentRepository.GetAllStudents();

    // 同時(shí)你也可以使用定義于IRepository<Student>中的方法， 比如:

    _studentRepository.Delete(students.First());
    _repositoryCenter.SaveChanges();

    ...

    return View(students);
}

四、思路總結(jié)

上面的設(shè)計(jì)，把Repository的通用代碼剝離到父類(lèi)中，同時(shí)又允許每個(gè)Repository擴(kuò)展自己的方法，達(dá)到了比較理想的狀態(tài)。

只是現(xiàn)在的設(shè)計(jì)和Autofac耦合了，但是如果想繼續(xù)剝離Autofac直接使用 _repositoryCenter.GetRepository<IStudentRepository>(); 的方式獲取IStudentRepository的實(shí)例就很困難了。