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[ASP.net教程]MVC5 网站开发之三 数据存储层功能实现


数据存储层在项目Ninesky.DataLibrary中实现,整个项目只有一个类Repository

Repository中实现增删改查询等方法供业务逻辑层调用,主要功能如下图:

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具体步骤

一、添加实体框架的引用。

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1、打开解决方案,选择项目Ninesky.DataLibrary,引用上右键,选择管理NuGet程序包。

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NuGet包管理器中的浏览标签中点击EntityFramework,点击右侧栏的安装按钮。

 

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在搜索框输入EntityFramework.zh-Hans,安装假体中文资源包。

二、实现数据仓储类

打开解决方案,选择项目Ninesky.DataLibrary,Class1.cs重命名为Repository.cs,在文档头添加using System.Data.Entity;将类名重命名为public class Repository。改为public class Repository<T> where T :class

1、DbContext属性

Repository类中添加如下代码 public DbContext DbContext { get; set; }

2、构造函数

为类中添加够高函数,可以直接传递DbContex。

public Repository()    { }    public Repository(DbContext dbContext)    {      DbContext = dbContext;    }

3、查找实体方法Find

Find有一个重载。两个方法分别可以根据ID和根据lamdba表达式查找实体。

/// <summary>    /// 查找实体    /// </summary>    /// <param name="ID">实体主键值</param>    /// <returns></returns>    public T Find(int ID)    {      return DbContext.Set<T>().Find(ID);    }    /// <summary>    /// 查找实体    /// </summary>    /// <param name="where">查询Lambda表达式</param>    /// <returns></returns>    public T Find(Expression<Func<T,bool>> where)    {      return DbContext.Set<T>().SingleOrDefault(where);    }

4、查找实体列表方法FindList

根据需要FindList进行多次重载

/// <summary>    /// 查找实体列表    /// </summary>    /// <returns></returns>    public IQueryable<T> FindList()    {      return DbContext.Set<T>();    }    /// <summary>    /// 查找实体列表    /// </summary>    /// <typeparam name="TKey">排序建类型</typeparam>    /// <param name="order">排序表达式</param>    /// <param name="asc">是否正序</param>    /// <returns></returns>    public IQueryable<T> FindList<TKey>(Expression<Func<T, TKey>> order, bool asc)    {      return asc ? DbContext.Set<T>().OrderBy(order) : DbContext.Set<T>().OrderByDescending(order);    }    /// <summary>    /// 查找实体列表    /// </summary>    /// <typeparam name="TKey">排序键类型</typeparam>    /// <param name="order">排序键</param>    /// <param name="asc">是否正序</param>    /// <param name="number">获取的记录数量</param>    /// <returns></returns>    public IQueryable<T> FindList<TKey>(Expression<Func<T, TKey>> order, bool asc,int number)    {      return asc ? DbContext.Set<T>().OrderBy(order).Take(number) : DbContext.Set<T>().OrderByDescending(order).Take(number);    }    /// <summary>    /// 查找实体列表    /// </summary>    /// <param name="where">查询Lambda表达式</param>    /// <returns></returns>    public IQueryable<T> FindList(Expression<Func<T, bool>> where)    {      return DbContext.Set<T>().Where(where);    }    /// <summary>    /// 查找实体列表    /// </summary>    /// <param name="where">查询Lambda表达式</param>    /// <param name="number">获取的记录数量</param>    /// <returns></returns>    public IQueryable<T> FindList(Expression<Func<T, bool>> where, int number)    {      return DbContext.Set<T>().Where(where).Take(number);    }    /// <summary>    /// 查找实体列表    /// </summary>    /// <typeparam name="TKey">排序键类型</typeparam>    /// <param name="where">查询Lambda表达式</param>    /// <param name="order">排序键</param>    /// <param name="asc">是否正序</param>    /// <returns></returns>    public IQueryable<T> FindList<TKey>(Expression<Func<T, bool>> where, Expression<Func<T, TKey>> order, bool asc)    {      return asc ? DbContext.Set<T>().Where(where).OrderBy(order) : DbContext.Set<T>().Where(where).OrderByDescending(order);    }    /// <summary>    /// 查找实体列表    /// </summary>    /// <typeparam name="TKey">排序键类型</typeparam>    /// <param name="where">查询Lambda表达式</param>    /// <param name="order">排序键</param>    /// <param name="asc">是否正序</param>    /// <param name="number">获取的记录数量</param>    /// <returns></returns>    public IQueryable<T> FindList<TKey>(Expression<Func<T, bool>> where, Expression<Func<T, TKey>> order, bool asc, int number)    {      return asc ? DbContext.Set<T>().Where(where).OrderBy(order).Take(number) : DbContext.Set<T>().Where(where).OrderByDescending(order).Take(number);    }

5、查找实体分页列表方法FindPageList

根据需要FindPageList进行多次重载

/// <summary>    /// 查找分页列表    /// </summary>    /// <param name="pageSize">每页记录数。必须大于1</param>    /// <param name="pageIndex">页码。首页从1开始,页码必须大于1</param>    /// <param name="totalNumber">总记录数</param>    /// <returns></returns>    public IQueryable<T> FindPageList(int pageSize, int pageIndex, out int totalNumber)    {      if (pageIndex < 1) pageIndex = 1;      if (pageSize < 1) pageSize = 10;      IQueryable<T> _list = DbContext.Set<T>();      totalNumber = _list.Count();      return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize);    }    /// <summary>    /// 查找分页列表    /// </summary>    /// <param name="pageSize">每页记录数。必须大于1</param>    /// <param name="pageIndex">页码。首页从1开始,页码必须大于1</param>    /// <param name="totalNumber">总记录数</param>    /// <param name="order">排序键</param>    /// <param name="asc">是否正序</param>    /// <returns></returns>    public IQueryable<T> FindPageList<TKey>(int pageSize, int pageIndex, out int totalNumber, Expression<Func<T, TKey>> order, bool asc)    {      if (pageIndex < 1) pageIndex = 1;      if (pageSize < 1) pageSize = 10;      IQueryable<T> _list = DbContext.Set<T>();      _list = asc ? _list.OrderBy(order) : _list.OrderByDescending(order);      totalNumber = _list.Count();      return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize);    }    /// <summary>    /// 查找分页列表    /// </summary>    /// <param name="pageSize">每页记录数。必须大于1</param>    /// <param name="pageIndex">页码。首页从1开始,页码必须大于1</param>    /// <param name="totalNumber">总记录数</param>    /// <param name="where">查询表达式</param>    public IQueryable<T> FindPageList(int pageSize, int pageIndex, out int totalNumber, Expression<Func<T, bool>> where)    {      if (pageIndex < 1) pageIndex = 1;      if (pageSize < 1) pageSize = 10;      IQueryable<T> _list = DbContext.Set<T>().Where(where);      totalNumber = _list.Count();      return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize);    }    /// <summary>    /// 查找分页列表    /// </summary>    /// <param name="pageSize">每页记录数。必须大于1</param>    /// <param name="pageIndex">页码。首页从1开始,页码必须大于1</param>    /// <param name="totalNumber">总记录数</param>    /// <param name="where">查询表达式</param>    /// <param name="order">排序键</param>    /// <param name="asc">是否正序</param>    public IQueryable<T> FindPageList<TKey>(int pageSize, int pageIndex, out int totalNumber, Expression<Func<T, bool>> where, Expression<Func<T, TKey>> order, bool asc)    {      if (pageIndex < 1) pageIndex = 1;      if (pageSize < 1) pageSize = 10;      IQueryable<T> _list = DbContext.Set<T>().Where(where);      _list = asc ? _list.OrderBy(order) : _list.OrderByDescending(order);      totalNumber = _list.Count();      return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize);    }

6、添加实体方法Add

Add 方法有一个重载,重载方法可以选择是否立即保存

/// <summary>    /// 添加实体    /// </summary>    /// <param name="entity">实体</param>    /// <returns>受影响的对象的数目</returns>    public int Add(T entity)    {      return Add(entity, true);    }    /// <summary>    /// 添加实体    /// </summary>    /// <param name="entity">实体</param>    /// <param name="isSave">是否立即保存</param>    /// <returns>在“isSave”为True时返回受影响的对象的数目,为False时直接返回0</returns>    public int Add(T entity,bool isSave)    {      DbContext.Set<T>().Add(entity);      return isSave ? DbContext.SaveChanges() : 0;    }

7、更新实体方法Update

Updae 方法有一个重载,重载方法可以选择是否立即保存

#region Update    /// <summary>    /// 更新实体【立即保存】    /// </summary>    /// <param name="entity">实体</param>    /// <returns>在“isSave”为True时返回受影响的对象的数目,为False时直接返回0</returns>    public int Update(T entity)    {      return Update(entity, true);    }    /// <summary>    /// 更新实体    /// </summary>    /// <param name="entity">实体</param>    /// <param name="isSave">是否立即保存</param>    /// <returns>在“isSave”为True时返回受影响的对象的数目,为False时直接返回0</returns>    public int Update(T entity, bool isSave)    {      DbContext.Set<T>().Attach(entity);      DbContext.Entry<T>(entity).State = EntityState.Modified;      return isSave ? DbContext.SaveChanges() : 0;    }

8、删除实体方法Delete

Delete 方法有两个重载,一个是可以选择否立即保存,另一个是批量删除

/// <summary>    /// 删除实体【立即保存】    /// </summary>    /// <param name="entity">实体</param>    /// <returns>受影响的对象的数目</returns>    public int Delete(T entity)    {      return Delete(entity, true);    }    /// <summary>    /// 删除实体    /// </summary>    /// <param name="entity">实体</param>    /// <param name="isSave">是否立即保存</param>    /// <returns>在“isSave”为True时返回受影响的对象的数目,为False时直接返回0</returns>    public int Delete(T entity,bool isSave)    {      DbContext.Set<T>().Remove(entity);      return isSave ? DbContext.SaveChanges() : 0;    }    /// <summary>    /// 批量删除实体    /// </summary>    /// <param name="entities">实体集合</param>    /// <returns>受影响的对象的数目</returns>    public int Delete(IEnumerable<T> entities)    {      DbContext.Set<T>().RemoveRange(entities);      return DbContext.SaveChanges();    }

9、统计记录数方法Count

Count 方法有一个重载,可以根据表达式进行统计

/// <summary>    /// 记录数    /// </summary>    /// <returns></returns>    public int Count()    {      return DbContext.Set<T>().Count();    }    /// <summary>    /// 记录数    /// </summary>    /// <param name="predicate">表达式</param>    /// <returns></returns>    public int Count(Expression<Func<T, bool>> predicate)    {      return DbContext.Set<T>().Count(predicate);    }

10、是否存在

/// <summary>    /// 记录是否存在    /// </summary>    /// <param name="predicate">表达式</param>    /// <returns></returns>    public bool IsContains(Expression<Func<T, bool>> predicate)    {      return Count(predicate) > 0;    }

11、保存到数据库

/// <summary>    /// 保存数据【在Add、Upate、Delete未立即保存的情况下使用】    /// </summary>    /// <returns>受影响的记录数</returns>    public int Save()    {      return DbContext.SaveChanges();    }

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代码见https://ninesky.codeplex.com/SourceControl/latest#Ninesky/Ninesky.DataLibrary/Repository.cs