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:
具体步骤
一、添加实体框架的引用
1、打开解决方案,选择项目Ninesky.DataLibrary,在引用上右键,选择管理NuGet程序包。
在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。
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,将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
在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。
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public Repository()
{ }
public Repository(DbContext dbContext)
{
DbContext = dbContext;
}
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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。
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/// <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);
}
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4、查找实体列表方法FindList
根据需要FindList进行多次重载
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/// <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);
}
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5、查找实体分页列表方法FindPageList
根据需要FindPageList进行多次重载
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/// <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);
}
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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
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/// <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;
}
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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
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#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;
}
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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
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/// <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();
}
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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
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/// <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);
}
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10、是否存在
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/// <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;
}
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11、保存到数据库
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/// <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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原文链接:http://www.cnblogs.com/mzwhj/p/5184186.html