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ASP.NET MVC5网站开发之实现数据存储层功能(三)

时间:2021-07-01 10:21:17 帮助过:15人阅读

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。

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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