entity framewrk访问数据库的方法
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entity framewrk访问数据库的封装类 (MSSql 数据库 )
using System;using System.Collections.Generic;using System.Data;using System.Data.Entity;using System.Data.Entity.Infrastructure;using System.Linq;using System.Linq.Expressions;using System.Reflection;using System.Text;namespace DAL{ public partial class MyEntities : DbContext { public MyEntities(): base(GetEntityConnectionString(connectionString)) { } private static string GetEntityConnectionString(string connectionString) { EntityConnectionStringBuilder entityBuilder = new EntityConnectionStringBuilder(); entityBuilder.Metadata = "res://*/MyDB.csdl|res://*/MyDB.ssdl|res://*/MyDB.msl"; entityBuilder.ProviderConnectionString = connectionString; entityBuilder.Provider = "System.Data.SqlClient"; return entityBuilder.ToString(); } } /**//// <summary> /// MSSql 数据库 数据层 父类 /// </summary> /// <typeparam name="T"></typeparam> public class BaseDAL<T> where T : class,new() { /**//// <summary> /// EF 上下文对象 /// </summary> MyEntities db = new MyEntities(); 1.0 新增实体，返回受影响的行数 + int Add(T model)#region 1.0 新增实体，返回受影响的行数 + int Add(T model) /**//// <summary> /// 1.0 新增实体，返回受影响的行数 /// </summary> /// <param name="model"></param> /// <returns>返回受影响的行数</returns> public int Add(T model) { db.Set<T>().Add(model); //保存成功后，会将自增的id设置给model的主键属性，并返回受影响的行数。 return db.SaveChanges(); } #endregion 新增实体，返回对应的实体对象 + T AddReturnModel(T model)#region 新增实体，返回对应的实体对象 + T AddReturnModel(T model) /**//// <summary> /// 1.1 新增实体，返回对应的实体对象 /// </summary> /// <param name="model"></param> /// <returns></returns> public T AddReturnModel(T model) { db.Set<T>().Add(model); db.SaveChanges(); return model; } #endregion 根据id删除 + int Del(T model)#region 根据id删除 + int Del(T model) /**//// <summary> /// 根据id删除 /// </summary> /// <param name="model">必须包含要删除id的对象</param> /// <returns></returns> public int Del(T model) { db.Set<T>().Attach(model); db.Set<T>().Remove(model); return db.SaveChanges(); } #endregion 根据条件删除 + int DelBy(Expression> delWhere)#region 根据条件删除 + int DelBy(Expression<Func<T, bool>> delWhere) /**//// <summary> /// 2.1 根据条件删除 /// </summary> /// <param name="delWhere"></param> /// <returns>返回受影响的行数</returns> public int DelBy(Expression<Func<T, bool>> delWhere) { //2.1.1 查询要删除的数据 List<T> listDeleting = db.Set<T>().Where(delWhere).ToList(); //2.1.2 将要删除的数据 用删除方法添加到 EF 容器中 listDeleting.ForEach(u => { db.Set<T>().Attach(u); //先附加到EF 容器 db.Set<T>().Remove(u); //标识为删除状态 }); //2.1.3 一次性生成sql语句 到数据库执行删除 return db.SaveChanges(); } #endregion 修改实体 + int Modify(T model)#region 修改实体 + int Modify(T model) /**//// <summary> /// 修改实体 /// </summary> /// <param name="model"></param> /// <returns></returns> public int Modify(T model) { DbEntityEntry entry = db.Entry<T>(model); entry.State = EntityState.Modified; return db.SaveChanges(); } #endregion 修改实体，可修改指定属性 + int Modify(T model, params string[] propertyNames)#region 修改实体，可修改指定属性 + int Modify(T model, params string[] propertyNames) /**//// <summary> /// 3.1 修改实体，可修改指定属性 /// </summary> /// <param name="model"></param> /// <param name="propertyName"></param> /// <returns></returns> public int Modify(T model, params string[] propertyNames) { //3.1.1 将对象添加到EF中 DbEntityEntry entry = db.Entry<T>(model); //3.1.2 先设置对象的包装状态为 Unchanged entry.State = EntityState.Unchanged; //3.1.3 循环被修改的属性名数组 foreach (string propertyName in propertyNames) { //将每个被修改的属性的状态设置为已修改状态；这样在后面生成的修改语句时，就只为标识为已修改的属性更新 entry.Property(propertyName).IsModified = true; } return db.SaveChanges(); } #endregion 批量修改 + int ModifyBy(T model, Expression> whereLambda, params string[] modifiedPropertyNames)#region 批量修改 + int ModifyBy(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedPropertyNames) /**//// <summary> /// 3.2 批量修改 /// </summary> /// <param name="model"></param> /// <param name="whereLambda"></param> /// <param name="modifiedPropertyNames"></param> /// <returns></returns> public int ModifyBy(T model, Expression<Func<T, bool>> whereLambda, params string[] modifiedPropertyNames) { //3.2.1 查询要修改的数据 List<T> listModifing = db.Set<T>().Where(whereLambda).ToList(); //3.2.2 获取实体类类型对象 Type t = typeof(T); //3.2.3 获取实体类所有的公共属性 List<PropertyInfo> propertyInfos = t.GetProperties(BindingFlags.Instance | BindingFlags.Public).ToList(); //3.2.4 创建实体属性字典集合 Dictionary<string, PropertyInfo> dicPropertys = new Dictionary<string, PropertyInfo>(); //3.2.5 将实体属性中要修改的属性名 添加到字典集合中 键：属性名 值：属性对象 propertyInfos.ForEach(p => { if (modifiedPropertyNames.Contains(p.Name)) { dicPropertys.Add(p.Name, p); } }); //3.2.6 循环要修改的属性名 foreach (string propertyName in modifiedPropertyNames) { //判断要修改的属性名是否在实体类的属性集合中存在 if (dicPropertys.ContainsKey(propertyName)) { //如果存在，则取出要修改的属性对象 PropertyInfo proInfo = dicPropertys[propertyName]; //取出要修改的值 object newValue = proInfo.GetValue(model, null); //批量设置要修改对象的属性 foreach (T item in listModifing) { //为要修改的对象的要修改的属性设置新的值 proInfo.SetValue(item, newValue, null); } } } //一次性生成sql语句 到数据库执行 return db.SaveChanges(); } #endregion 根据条件查询单个model + T GetModel(Expression> whereLambda)#region 根据条件查询单个model + T GetModel(Expression<Func<T, bool>> whereLambda) /**//// <summary> /// 4.0 根据条件查询单个model /// </summary> /// <param name="whereLambda"></param> /// <returns></returns> public T GetModel(Expression<Func<T, bool>> whereLambda) { return db.Set<T>().Where(whereLambda).AsNoTracking().FirstOrDefault(); } #endregion 根据条件查询单个model并排序 + T GetModel(Expression> whereLambda, Expression> orderLambda, bool isAsc = true)#region 根据条件查询单个model并排序 + T GetModel<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda, bool isAsc = true) /**//// <summary> /// 4.1 根据条件查询单个model并排序 /// </summary> /// <typeparam name="TKey"></typeparam> /// <param name="whereLambda"></param> /// <param name="orderLambda"></param> /// <param name="isAsc"></param> /// <returns></returns> public T GetModel<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda, bool isAsc = true) { if (isAsc) { return db.Set<T>().Where(whereLambda).OrderBy(orderLambda).AsNoTracking().FirstOrDefault(); } else { return db.Set<T>().Where(whereLambda).OrderByDescending(orderLambda).AsNoTracking().FirstOrDefault(); } } #endregion 根据条件查询 + List GetListBy(Expression> whereLambda)#region 根据条件查询 + List<T> GetListBy(Expression<Func<T, bool>> whereLambda) /**//// <summary> /// 5.0 根据条件查询 /// </summary> /// <param name="whereLambda"></param> /// <returns></returns> public List<T> GetListBy(Expression<Func<T, bool>> whereLambda) { return db.Set<T>().Where(whereLambda).AsNoTracking().ToList(); } #endregion 根据条件查询，并排序 + List GetListBy(Expression> whereLambda, Expression> orderLambda, bool isAsc = true)#region 根据条件查询，并排序 + List<T> GetListBy<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda, bool isAsc = true) /**//// <summary> /// 5.1 根据条件查询，并排序 /// </summary> /// <typeparam name="TKey"></typeparam> /// <param name="whereLambda"></param> /// <param name="orderLambda"></param> /// <param name="isAsc"></param> /// <returns></returns> public List<T> GetListBy<TKey>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda, bool isAsc = true) { if (isAsc) { return db.Set<T>().Where(whereLambda).OrderBy(orderLambda).AsNoTracking().ToList(); } else { return db.Set<T>().Where(whereLambda).OrderByDescending(orderLambda).AsNoTracking().ToList(); } } #endregion 根据条件查询Top多少个，并排序 + List GetListBy(int top, Expression> whereLambda, Expression> orderLambda, bool isAsc = true)#region 根据条件查询Top多少个，并排序 + List<T> GetListBy<TKey>(int top, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda, bool isAsc = true) /**//// <summary> /// 5.2 根据条件查询Top多少个，并排序 /// </summary> /// <typeparam name="TKey"></typeparam> /// <param name="top"></param> /// <param name="whereLambda"></param> /// <param name="orderLambda"></param> /// <param name="isAsc"></param> /// <returns></returns> public List<T> GetListBy<TKey>(int top, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderLambda, bool isAsc = true) { if (isAsc) { return db.Set<T>().Where(whereLambda).OrderBy(orderLambda).Take(top).AsNoTracking().ToList(); } else { return db.Set<T>().Where(whereLambda).OrderByDescending(orderLambda).Take(top).AsNoTracking().ToList(); } } #endregion 根据条件排序查询 双排序 + List GetListBy(Expression> whereLambda, Expression> orderLambda1, Expression> orderLambda2, bool isAsc1 = true, bool isAsc2 = true)#region 根据条件排序查询 双排序 + List<T> GetListBy<TKey1, TKey2>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey1>> orderLambda1, Expression<Func<T, TKey2>> orderLambda2, bool isAsc1 = true, bool isAsc2 = true) /**//// <summary> /// 5.3 根据条件排序查询 双排序 /// </summary> /// <typeparam name="TKey1"></typeparam> /// <typeparam name="TKey2"></typeparam> /// <param name="whereLambda"></param> /// <param name="orderLambda1"></param> /// <param name="orderLambda2"></param> /// <param name="isAsc1"></param> /// <param name="isAsc2"></param> /// <returns></returns> public List<T> GetListBy<TKey1, TKey2>(Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey1>> orderLambda1, Expression<Func<T, TKey2>> orderLambda2, bool isAsc1 = true, bool isAsc2 = true) { if (isAsc1) { if (isAsc2) { return db.Set<T>().Where(whereLambda).OrderBy(orderLambda1).ThenBy(orderLambda2).AsNoTracking().ToList(); } else { return db.Set<T>().Where(whereLambda).OrderBy(orderLambda1).ThenByDescending(orderLambda2).AsNoTracking().ToList(); } } else { if (isAsc2) { return db.Set<T>().Where(whereLambda).OrderByDescending(orderLambda1).ThenBy(orderLambda2).AsNoTracking().ToList(); } else { return db.Set<T>().Where(whereLambda).OrderByDescending(orderLambda1).ThenByDescending(orderLambda2).AsNoTracking().ToList(); } } } #endregion 根据条件排序查询Top个数 双排序 + List GetListBy(int top, Expression> whereLambda, System.Linq.Expressions.Expression> orderLambda1, Expression> orderLambda2, bool isAsc1 = true, bool isAsc2 = true)#region 根据条件排序查询Top个数 双排序 + List<T> GetListBy<TKey1, TKey2>(int top, Expression<Func<T, bool>> whereLambda, System.Linq.Expressions.Expression<Func<T, TKey1>> orderLambda1, Expression<Func<T, TKey2>> orderLambda2, bool isAsc1 = true, bool isAsc2 = true) /**//// <summary> /// 5.3 根据条件排序查询Top个数 双排序 /// </summary> /// <typeparam name="TKey1"></typeparam> /// <typeparam name="TKey2"></typeparam> /// <param name="top"></param> /// <param name="whereLambda"></param> /// <param name="orderLambda1"></param> /// <param name="orderLambda2"></param> /// <param name="isAsc1"></param> /// <param name="isAsc2"></param> /// <returns></returns> public List<T> GetListBy<TKey1, TKey2>(int top, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey1>> orderLambda1, Expression<Func<T, TKey2>> orderLambda2, bool isAsc1 = true, bool isAsc2 = true) { if (isAsc1) { if (isAsc2) { return db.Set<T>().Where(whereLambda).OrderBy(orderLambda1).ThenBy(orderLambda2).Take(top).AsNoTracking().ToList(); } else { return db.Set<T>().Where(whereLambda).OrderBy(orderLambda1).ThenByDescending(orderLambda2).Take(top).AsNoTracking().ToList(); } } else { if (isAsc2) { return db.Set<T>().Where(whereLambda).OrderByDescending(orderLambda1).ThenBy(orderLambda2).Take(top).AsNoTracking().ToList(); } else { return db.Set<T>().Where(whereLambda).OrderByDescending(orderLambda1).ThenByDescending(orderLambda2).Take(top).AsNoTracking().ToList(); } } } #endregion 分页查询 + List GetPagedList#region 分页查询 + List<T> GetPagedList<TKey> /**//// <summary> /// 分页查询 + List<T> GetPagedList /// </summary> /// <typeparam name="TKey"></typeparam> /// <param name="pageIndex">页码</param> /// <param name="pageSize">页容量</param> /// <param name="whereLambda">条件 lambda表达式</param> /// <param name="orderBy">排序 lambda表达式</param> /// <returns></returns> public List<T> GetPagedList<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderByLambda, bool isAsc = true) { // 分页 一定注意： Skip 之前一定要 OrderBy if (isAsc) { return db.Set<T>().Where(whereLambda).OrderBy(orderByLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } else { return db.Set<T>().Where(whereLambda).OrderByDescending(orderByLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } } #endregion 分页查询 带输出 +List GetPagedList#region 分页查询 带输出 +List<T> GetPagedList<TKey> /**//// <summary> /// 分页查询 带输出 /// </summary> /// <typeparam name="TKey"></typeparam> /// <param name="pageIndex"></param> /// <param name="pageSize"></param> /// <param name="rowCount"></param> /// <param name="whereLambda"></param> /// <param name="orderBy"></param> /// <param name="isAsc"></param> /// <returns></returns> public List<T> GetPagedList<TKey>(int pageIndex, int pageSize, ref int rowCount, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey>> orderByLambda, bool isAsc = true) { rowCount = db.Set<T>().Where(whereLambda).Count(); if (isAsc) { return db.Set<T>().OrderBy(orderByLambda).Where(whereLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } else { return db.Set<T>().OrderByDescending(orderByLambda).Where(whereLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } } #endregion 分页查询 带输出 并支持双字段排序#region 分页查询 带输出 并支持双字段排序 /**//// <summary> /// 分页查询 带输出 并支持双字段排序 /// </summary> /// <typeparam name="TKey"></typeparam> /// <param name="pageIndex"></param> /// <param name="pageSize"></param> /// <param name="rowCount"></param> /// <param name="whereLambda"></param> /// <param name="orderByLambda1"></param> /// <param name="orderByLambda2"></param> /// <param name="isAsc1"></param> /// <param name="isAsc2"></param> /// <returns></returns> public List<T> GetPagedList<TKey1, TKey2>(int pageIndex, int pageSize, ref int rowCount, Expression<Func<T, bool>> whereLambda, Expression<Func<T, TKey1>> orderByLambda1, Expression<Func<T, TKey2>> orderByLambda2, bool isAsc1 = true, bool isAsc2 = true) { rowCount = db.Set<T>().Where(whereLambda).Count(); if (isAsc1) { if (isAsc2) { return db.Set<T>().OrderBy(orderByLambda1).ThenBy(orderByLambda2).Where(whereLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } else { return db.Set<T>().OrderBy(orderByLambda1).ThenByDescending(orderByLambda2).Where(whereLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } } else { if (isAsc2) { return db.Set<T>().OrderByDescending(orderByLambda1).ThenBy(orderByLambda2).Where(whereLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } else { return db.Set<T>().OrderByDescending(orderByLambda1).ThenByDescending(orderByLambda2).Where(whereLambda).Skip((pageIndex - 1) * pageSize).Take(pageSize).AsNoTracking().ToList(); } } } #endregion }}文章转载自： entity framewrk访问数据库的封装类 http://www.studyofnet.com/news/768.html
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