前一篇介绍了仓储的基本概念，并谈了我对仓储的一些认识，本文将实现仓储的基本功能。
仓储代表聚合在内存中的集合，所以仓储的接口需要模拟得像一个集合。仓储中有很多操作都是可以通用的，可以把这部分操作抽取到基类中。
在Util.Domains项目中创建一个文件夹Repositories，这个文件夹用来放仓储相关的接口。在Repositories下创建一个仓储接口IRepository。
把仓储基接口放到Util.Domains，是因为仓储接口是在领域层定义的，这与传统三层架构的数据访问层接口的位置不同。
仓储是基础设施层的组成部分，位于领域层的下方，按理来说，领域层应该依赖仓储，但这会导致领域层与具体数据访问组件耦合，降低了领域层的复用能力。为了让领域层更加纯净，可以应用依赖倒置原则（DIP）。依赖倒置原则提到，高层模块不应该依赖低层模块，这里的高层模块就是领域层，低层模块是基础设施层的仓储。
依赖倒置原则反转了两者的依赖关系，即仓储反过来依赖于领域层。为了让领域层可以访问到仓储提供的服务，需要抽取仓储接口，你可以把这些接口放到独立的程序集中，但这会增加不必要的开销。一种更好的方法是直接把低层接口放入使用它们的客户程序集中，这样可以简化设计，仅在必要时才分离出独立的接口程序集。依赖倒置原则不仅适用于仓储，对于任何可能导致高耦合的基础设施服务都适用，比如第三方外部接口，发邮件，发短信等。
在Util.Datas.Ef项目中创建一个仓储实现类Repository。
仓储接口IRepository的代码如下。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using Util.Datas;
namespace Util.Domains.Repositories {
/// <summary>
/// 仓储
/// </summary>
/// <typeparam name="TEntity">实体类型</typeparam>
/// <typeparam name="TKey">实体标识类型</typeparam>
public interface IRepository<TEntity, in TKey> where TEntity : class, IAggregateRoot<TKey> {
/// <summary>
/// 添加实体
/// </summary>
/// <param name="entity">实体</param>
void Add( TEntity entity );
/// <summary>
/// 添加实体
/// </summary>
/// <param name="entities">实体</param>
void Add( IEnumerable<TEntity> entities );
/// <summary>
/// 修改实体
/// </summary>
/// <param name="entity">实体</param>
void Update( TEntity entity );
/// <summary>
/// 移除实体
/// </summary>
/// <param name="id">实体标识</param>
void Remove( TKey id );
/// <summary>
/// 移除实体
/// </summary>
/// <param name="entity">实体</param>
void Remove( TEntity entity );
/// <summary>
/// 查找实体集合
/// </summary>
List<TEntity> FindAll();
/// <summary>
/// 查找实体集合
/// </summary>
IQueryable<TEntity> Find();
/// <summary>
/// 查找实体
/// </summary>
/// <param name="id">实体标识</param>
TEntity Find( params object[] id );
/// <summary>
/// 查找实体列表
/// </summary>
/// <param name="ids">实体标识列表</param>
List<TEntity> Find( IEnumerable<TKey> ids );
/// <summary>
/// 判断实体是否存在
/// </summary>
/// <param name="predicate">条件</param>
bool Exists( Expression<Func<TEntity, bool>> predicate );
/// <summary>
/// 索引器查找，获取指定标识的实体
/// </summary>
/// <param name="id">实体标识</param>
TEntity this[TKey id] { get; }
/// <summary>
/// 保存
/// </summary>
void Save();
/// <summary>
/// 获取工作单元
/// </summary>
IUnitOfWork GetUnitOfWork();
}
}
using System;
namespace Util.Domains.Repositories {
/// <summary>
/// 仓储
/// </summary>
/// <typeparam name="TEntity">实体类型</typeparam>
public interface IRepository<TEntity> : IRepository<TEntity, Guid> where TEntity : class, IAggregateRoot<Guid> {
}
}
仓储实现类Repository的代码如下。
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Linq.Expressions;
using Util.Domains;
using Util.Domains.Repositories;
namespace Util.Datas.Ef {
/// <summary>
/// 仓储
/// </summary>
/// <typeparam name="TEntity">实体类型</typeparam>
/// <typeparam name="TKey">实体标识类型</typeparam>
public abstract class Repository<TEntity, TKey> : IRepository<TEntity, TKey> where TEntity : class, IAggregateRoot<TKey> {
/// <summary>
/// 初始化仓储
/// </summary>
/// <param name="unitOfWork">工作单元</param>
protected Repository( IUnitOfWork unitOfWork ) {
UnitOfWork = (EfUnitOfWork)unitOfWork;
}
/// <summary>
/// Ef工作单元
/// </summary>
protected EfUnitOfWork UnitOfWork { get; private set; }
/// <summary>
/// 添加实体
/// </summary>
/// <param name="entity">实体</param>
public void Add( TEntity entity ) {
UnitOfWork.Set<TEntity>().Add( entity );
UnitOfWork.CommitByStart();
}
/// <summary>
/// 添加实体
/// </summary>
/// <param name="entities">实体</param>
public void Add( IEnumerable<TEntity> entities ) {
if ( entities == null )
return;
UnitOfWork.Set<TEntity>().AddRange( entities );
UnitOfWork.CommitByStart();
}
/// <summary>
/// 修改实体
/// </summary>
/// <param name="entity">实体</param>
public virtual void Update( TEntity entity ) {
UnitOfWork.Entry( entity ).State = EntityState.Modified;
UnitOfWork.CommitByStart();
}
/// <summary>
/// 移除实体
/// </summary>
/// <param name="id">实体标识</param>
public void Remove( TKey id ) {
var entity = Find( id );
if ( entity == null )
return;
Remove( entity );
}
/// <summary>
/// 移除实体
/// </summary>
/// <param name="entity">实体</param>
public void Remove( TEntity entity ) {
UnitOfWork.Set<TEntity>().Remove( entity );
UnitOfWork.CommitByStart();
}
/// <summary>
/// 查找实体集合
/// </summary>
public List<TEntity> FindAll() {
return Find().ToList();
}
/// <summary>
/// 查找实体
/// </summary>
public IQueryable<TEntity> Find() {
return UnitOfWork.Set<TEntity>();
}
/// <summary>
/// 查找实体
/// </summary>
/// <param name="id">实体标识</param>
public TEntity Find( params object[] id ) {
return UnitOfWork.Set<TEntity>().Find( id );
}
/// <summary>
/// 查找实体列表
/// </summary>
/// <param name="ids">实体标识列表</param>
public List<TEntity> Find( IEnumerable<TKey> ids ) {
if ( ids == null )
return null;
return Find().Where( t => ids.Contains( t.Id ) ).ToList();
}
/// <summary>
/// 索引器查找，获取指定标识的实体
/// </summary>
/// <param name="id">实体标识</param>
public TEntity this[TKey id] {
get { return Find( id ); }
}
/// <summary>
/// 判断实体是否存在
/// </summary>
/// <param name="predicate">条件</param>
public bool Exists( Expression<Func<TEntity, bool>> predicate ) {
return Find().Any( predicate );
}
/// <summary>
/// 保存
/// </summary>
public void Save() {
UnitOfWork.Commit();
}
/// <summary>
/// 获取工作单元
/// </summary>
public IUnitOfWork GetUnitOfWork() {
return UnitOfWork;
}
}
}
using System;
using Util.Domains;
namespace Util.Datas.Ef {
/// <summary>
/// 仓储
/// </summary>
/// <typeparam name="TEntity">实体类型</typeparam>
public abstract class Repository<TEntity> : Repository<TEntity, Guid> where TEntity : class, IAggregateRoot<Guid> {
/// <summary>
/// 初始化仓储
/// </summary>
/// <param name="unitOfWork">工作单元</param>
protected Repository( IUnitOfWork unitOfWork )
: base( unitOfWork ) {
}
}
}
仓储是对聚合的操作，所以泛型接口声明IRepository<TEntity, in TKey> where TEntity : class, IAggregateRoot<TKey>对TEntity类型限定为聚合。
在Repository实现类中，通过注入DbContext工作单元来完成所有的工作。IUnitOfWork和EfUnitOfWork是在应用程序框架实战十九:工作单元层超类型中定义的，EfUnitOfWork从DbContext派生，它有一个核心方法CommitByStart，用来告诉仓储，如果开启了工作单元就等待调用端通过Commit提交，否则立即提交。每个数据更新方法Add、Update、Remove都会调用CommitByStart方法。
对于使用Entity Framework 进行Update修改操作有多种实现方式。在仓储基类中实现的Update方法比较通用，但我手工编写代码时一般会直接把聚合取出来，修改聚合属性，再提交工作单元。
本文介绍了仓储通用操作的基本实现，后续文章我将介绍如何通过表达式树对查询扩展和封装。
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Entity;
using System.Linq;
using System.Linq.Expressions;
using Webdiyer.WebControls.Mvc;
using System.Text;
using BExpress.Model;
namespace BExpress.DAL.Repositories
{
using System.Data.Entity.Validation;
/// <summary>
/// 通用仓储实现类
/// </summary>
/// <typeparam name="TEntity"><see cref="T:System.Data.Entity.DbSet`1"/></typeparam>
public class GenericRepository<TEntity> where TEntity : class
{
public BExpressDbContext context;
public DbSet<TEntity> dbSet;
/// <summary>
/// 实例化一个仓储基类实现
/// </summary>
/// <param name="context">EF 上下文</param>
public GenericRepository(BExpressDbContext context)
{
this.context = context;
this.dbSet = context.Set<TEntity>();
}
/// <summary>
/// 根据查询条件或排序规则获得实体集合
/// </summary>
/// <param name="filter">过滤条件</param>
/// <param name="orderBy">排序规则</param>
/// <param name="includeProperties">包含的外键属性名</param>
/// <returns></returns>
public virtual IEnumerable<TEntity> Get(
Expression<Func<TEntity, bool>> filter = null,
Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
string includeProperties = "")
{
IQueryable<TEntity> query = dbSet;
if (filter != null)
{
query = query.Where(filter);
}
query = includeProperties.Split(new[] {‘,‘}, StringSplitOptions.RemoveEmptyEntries).Aggregate(query, (current, includeProperty) => current.Include(includeProperty));
return orderBy != null ? orderBy(query).ToList() : query.ToList();
}
/// <summary>
/// 获取一个包装成<see cref="T:Webdiyer.WebControls.Mvc.PagedList`1"/>的实体集合
/// </summary>
/// <param name="filter">过滤条件</param>
/// <param name="orderBy">排序规则</param>
/// <param name="includeProperties">包含的外键属性名</param>
/// <param name="pageIndex">页索引</param>
/// <param name="pageSize">页大小</param>
/// <returns></returns>
public virtual PagedList<TEntity> GetPaging(Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy,
Expression<Func<TEntity, bool>> filter = null,
string includeProperties = "", int pageIndex = 1, int pageSize = 20)
{
IQueryable<TEntity> query = dbSet;
if (filter != null)
{
query = query.Where(filter);
}
query = includeProperties.Split(new[] {‘,‘}, StringSplitOptions.RemoveEmptyEntries).Aggregate(query, (current, includeProperty) => current.Include(includeProperty));
var list = orderBy(query).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsEnumerable();
var count = 0;
count = filter == null ? dbSet.Count() : dbSet.Count(filter);
return new PagedList<TEntity>(list, pageIndex, pageSize, count);
}
/// <summary>
/// 根据查询条件或排序规则获得单个实体
/// </summary>
/// <param name="filter">过滤条件</param>
/// <param name="orderBy">排序规则</param>
/// <param name="includeProperties">包含的外键属性名</param>
/// <param name="isAttach">是否附加到DbContext上下文进行跟踪</param>
/// <returns></returns>
public virtual TEntity GetFirst(Expression<Func<TEntity, bool>> filter = null, Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
string includeProperties = "", bool isAttach = true)
{
IQueryable<TEntity> query = dbSet;
if (filter != null)
{
query = query.Where(filter);
}
query = includeProperties.Split(new[] {‘,‘}, StringSplitOptions.RemoveEmptyEntries).Aggregate(query, (current, includeProperty) => current.Include(includeProperty));
//if (orderBy != null)
//{
// return isAttach ? orderBy(query).FirstOrDefault() : orderBy(query).AsNoTracking().FirstOrDefault();
//}
return isAttach ? query.FirstOrDefault() : query.AsNoTracking().FirstOrDefault();
}
/// <summary>
/// 根据主键Id获取单个实体对象
/// </summary>
/// <param name="id">id,通常是主键</param>
public virtual TEntity GetByID(object id)
{
return dbSet.Find(id);
}
/// <summary>
/// 获取单个(不会被跟踪)实体
/// </summary>
/// <param name="pred">条件谓词</param>
/// <returns><see cref="TEntity"/></returns>
public virtual TEntity SingleOrDefault(Func<TEntity, bool> pred)
{
var obj = dbSet.AsNoTracking().SingleOrDefault(pred);
return obj;
}
/// <summary>
/// 插入一个实体对象
/// <para>需手动调用Save方法</para>
/// </summary>
/// <param name="entity">实体对象</param>
/// <returns></returns>
public virtual TEntity Insert(TEntity entity)
{
return dbSet.Add(entity);
}
/// <summary>
/// 根据实体主键删除实体对象
/// <para>需手动调用Save方法</para>
/// </summary>
/// <param name="id">通常是主键id</param>
public virtual void Delete(object id)
{
TEntity entityToDelete = dbSet.Find(id);
Delete(entityToDelete);
}
/// <summary>
/// 根据主键Id集合批量删除实体
/// <para>需手动调用Save方法</para>
/// </summary>
/// <param name="ids"></param>
public virtual void DeleteMultiple(IEnumerable<int> ids)
{
if (ids == null) return;
foreach (TEntity entityToDelete in ids.Select(id => dbSet.Find(id)))
{
if (entityToDelete == null)
{
continue;
}
Delete(entityToDelete);
}
}
/// <summary>
/// 删除单个实体
/// <para>需手动调用Save方法</para>
/// </summary>
/// <param name="entityToDelete">要删除的实体对象</param>
public virtual void Delete(TEntity entityToDelete)
{
if (context.Entry(entityToDelete).State == EntityState.Detached)
{
dbSet.Attach(entityToDelete);
}
dbSet.Remove(entityToDelete);
}
/// <summary>
/// 更新一个实体
/// <para>需手动调用Save方法</para>
/// </summary>
/// <param name="entityToUpdate">要被更新的实体对象</param>
public virtual void Update(TEntity entityToUpdate)
{
//dbSet.Attach(entityToUpdate);
if (context.Entry(entityToUpdate).State == EntityState.Detached)
{
dbSet.Attach(entityToUpdate);
}
context.Entry(entityToUpdate).State = EntityState.Modified;
}
/// <summary>
/// 根据原生SQL语句查询<see cref="TEntity"/>实体集合
/// </summary>
/// <param name="query">SQL语句</param>
/// <param name="parameters">参数</param>
/// <returns></returns>
public virtual IEnumerable<TEntity> GetWithRawSql(string query, params object[] parameters)
{
return dbSet.SqlQuery(query, parameters).ToList();
}
/// <summary>
/// 根据条件获得实体对象的数量
/// </summary>
/// <param name="filter">过滤条件</param>
/// <returns></returns>
public virtual int Count(Expression<Func<TEntity, bool>> filter = null)
{
return filter != null ? dbSet.Count(filter) : dbSet.Count();
}
#region AddTime:20140821 11:30 By:Ax0ne
/// <summary>
/// 获取实体中单个属性值
/// </summary>
/// <typeparam name="T">返回值的类型</typeparam>
/// <param name="selector">返回哪个属性值</param>
/// <param name="predicate">条件</param>
/// <returns></returns>
public virtual T GetField<T>(Expression<Func<TEntity, T>> selector, Expression<Func<TEntity, bool>> predicate, string includeProperties = "")
{
IQueryable<TEntity> query = dbSet;
if (!string.IsNullOrWhiteSpace(includeProperties))
{
query = includeProperties.Split(new[] { ‘,‘ }, StringSplitOptions.RemoveEmptyEntries).Aggregate(query, (current, includeProperty) => current.Include(includeProperty));
}
return query.Where(predicate).Select(selector).FirstOrDefault();
}
/// <summary>
/// 获取实体中单个属性值
/// <para>返回Ienumerable,可以直接把返回结果写在下条查询里,这样原本两条查询就变成一条.ToList或遍历就可以立即查询</para>
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="selector"></param>
/// <param name="predicate"></param>
/// <returns></returns>
public virtual IEnumerable<T> GetFields<T>(Expression<Func<TEntity, T>> selector, Expression<Func<TEntity, bool>> predicate)
{
// AddTime:20141112 14:05 by:Ax0ne
return dbSet.Where(predicate).Select(selector).AsEnumerable();
}
/// <summary>
/// 判断实体对象是否存在
/// </summary>
/// <param name="filter">条件</param>
/// <returns></returns>
public virtual bool IsExist(Expression<Func<TEntity, bool>> filter)
{
return Count(filter) > 0;
}
#region AddTime:20150123 17:00
private int Add(TEntity instance, bool isSave = true, bool attach = true)
{
if (attach)
{
this.dbSet.Attach(instance);
}
this.context.Entry(instance).State = EntityState.Added;
if (isSave)
{
return Save();
}
else
{
return 0;
}
}
/// <summary>
/// 批量添加实体对象
/// </summary>
/// <param name="entities">实体对象集合</param>
/// <param name="isSave">是否保存</param>
/// <returns></returns>
public int AddBatch(IEnumerable<TEntity> entities, bool isSave = true)
{
return InnerOperator(entities, o => Add(o, false), isSave);
}
private int InnerOperator(IEnumerable<TEntity> entities, Func<TEntity, int> method, bool isSave)
{
// 方法的封装
// AddTime:20141011 11:50
int result = 0;
foreach (var item in entities)
{
method(item);
}
if (isSave)
{
this.context.Configuration.AutoDetectChangesEnabled = false;
this.context.Configuration.ValidateOnSaveEnabled = false;
try
{
result = Save();
}
finally
{
this.context.Configuration.AutoDetectChangesEnabled = true;
this.context.Configuration.ValidateOnSaveEnabled = true;
}
}
return result;
}
/// <summary>
/// 批量更新实体对象
/// </summary>
/// <param name="entities">实体对象集合</param>
/// <param name="isSave">是否保存</param>
/// <returns></returns>
public int UpdateBatch(IEnumerable<TEntity> entities, bool isSave = true)
{
return InnerOperator(entities, o => Update(o, false), isSave);
}
private int Update(TEntity instance, bool isSave = true, bool attach = true)
{
if (attach)
{
this.dbSet.Attach(instance);
}
this.context.Entry(instance).State = EntityState.Modified;
if (isSave)
{
return Save();
}
else
{
return 0;
}
}
private int Save()
{
int result = 0;
try
{
result = context.SaveChanges();
}
catch (Exception exception)
{
Exception ex = exception;
while (ex.InnerException != null)
{
ex = ex.InnerException;
}
var entityException = ex as DbEntityValidationException;
if (entityException != null)
{
foreach (var errs in entityException.EntityValidationErrors)
{
foreach (var err in errs.ValidationErrors)
{
string exMessage = string.Format("\r\n属性[ {0} ] 的异常信息--->>>{1}", err.PropertyName, err.ErrorMessage);
System.Diagnostics.Trace.TraceError(exMessage);
throw new DbEntityValidationException(exMessage);
}
}
}
throw new Exception(ex.Message);
}
return result;
}
#endregion
/// <summary>
/// 执行DML语句 多条用 ; 结尾
/// </summary>
/// <param name="sqlText"></param>
/// <returns></returns>
public bool ExecuteSqlCommand(string sqlText)
{
if (string.IsNullOrWhiteSpace(sqlText)) return false;
context.Database.CommandTimeout = 120;
return context.Database.ExecuteSqlCommand(sqlText) > 0;
}
/// <summary>
/// 参数化执行DML语句 多条用 ; 结尾
/// </summary>
/// <param name="sqlText"></param>
/// <param name="parameters"></param>
/// <returns></returns>
public bool ExecuteSqlCommand(string sqlText, params object[] parameters)
{
if (string.IsNullOrWhiteSpace(sqlText)) return false;
return context.Database.ExecuteSqlCommand(sqlText, parameters) > 0;
}
#endregion
}
}
原文地址：https://www.cnblogs.com/w2017/p/8280123.html