为什么要使用泛型仓储？好处是？
前两章在autofac注入的时候，用的User类作为例子，写了增删改查四个接口，也就是仓储的GRUD。
当我们再添加一个实体（比如Student）时，StudentRepository跟UserRepository代码几乎一样的代码，重复量很大，为了减少冗余、提高工作效率，使用泛型仓储最好不过了
好处：
减少代码冗余
提高了开发人员的工作效率
提高对数据库访问的维护
一、泛型仓储接口和泛型仓储实现类
泛型仓储接口
在类库项目上右键->添加->新建文件夹，命名为Repository，存放泛型仓储类。在Repository文件夹下面新建 泛型仓储接口类：IRepository，如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using NetCoreWebApi.Repository.Dto; namespace NetCoreWebApi.Repository.Repository
{
public interface IRepository<T> where T : class
{
/// <summary>
/// 添加实体(单个)
/// </summary>
/// <param name="entity">实体对象</param>
int Add(T entity); /// <summary>
/// 批量插入实体(多个)
/// </summary>
/// <param name="list">实体列表</param>
int AddRange(List<T> list); /// <summary>
/// 删除实体(单个)
/// </summary>
/// <param name="entity"></param>
int Remove(T entity); /// <summary>
/// 批量删除实体(多个)
/// </summary>
/// <param name="list">实体列表</param>
int RemoveRange(List<T> list);
/// <summary>
/// 获取所有
/// </summary>
/// <returns></returns>
IQueryable<T> GetAll();
/// <summary>
/// 分页条件查询
/// </summary>
/// <typeparam name="TKey">排序类型</typeparam>
/// <param name="pageIndex">当前页</param>
/// <param name="pageSize">每页大小</param>
/// <param name="predicate">条件表达式</param>
/// <param name="isAsc">是否升序排列</param>
/// <param name="keySelector">排序表达式</param>
/// <returns></returns>
Page<T> SearchFor<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> predicate,
bool isAsc, Expression<Func<T, TKey>> keySelector);
/// <summary>
/// 获取实体（主键）
/// </summary>
/// <param name="id">主键id</param>
/// <returns></returns>
T GetModelById(object id);
/// <summary>
/// 获取实体（条件）
/// </summary>
/// <param name="predicate">条件表达式</param>
/// <returns></returns>
T GetModel(Expression<Func<T, bool>> predicate);
/// <summary>
/// 查询记录数
/// </summary>
/// <param name="predicate">条件表达式</param>
/// <returns>记录数</returns>
int Count(Expression<Func<T, bool>> predicate);
/// <summary>
/// 是否存在
/// </summary>
/// <param name="anyLambda">查询表达式</param>
/// <returns>布尔值</returns>
bool Exist(Expression<Func<T, bool>> anyLambda);
}
}
泛型仓储实现类
在Repository文件夹下面新建 泛型仓储实现类：Repository，并继承IRepository，如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using Microsoft.EntityFrameworkCore;
using NetCoreWebApi.Model;
using NetCoreWebApi.Repository.Dto; namespace NetCoreWebApi.Repository.Repository
{
public class Repository<T> : IRepository<T> where T : class
{
private readonly MyDbContext _dbContext;
private DbSet<T> _entity; /// <summary>
/// 构造函数
/// </summary>
/// <param name="dbContext"></param>
public Repository(MyDbContext dbContext)
{
_dbContext = dbContext;
}
private DbSet<T> Entity => _entity ?? (_entity = _dbContext.Set<T>());
/// <summary>
/// 添加实体(单个)
/// </summary>
/// <param name="entity">实体对象</param>
public int Add(T entity)
{
Entity.Add(entity);
return _dbContext.SaveChanges();
}
/// <summary>
/// 批量插入实体(多个)
/// </summary>
/// <param name="list">实体列表</param>
public int AddRange(List<T> list)
{
Entity.AddRange(list);
return _dbContext.SaveChanges();
} /// <summary>
/// 删除实体(单个)
/// </summary>
/// <param name="entity"></param>
public int Remove(T entity)
{
Entity.Remove(entity);
return _dbContext.SaveChanges();
}
/// <summary>
/// 批量删除实体(多个)
/// </summary>
/// <param name="list">实体列表</param>
public int RemoveRange(List<T> list)
{
Entity.RemoveRange(list);
return _dbContext.SaveChanges();
}
/// <summary>
/// 获取所有
/// </summary>
/// <returns></returns>
public IQueryable<T> GetAll()
{
return Entity.AsQueryable().AsNoTracking();
}
/// <summary>
/// 条件查询
/// </summary>
/// <typeparam name="TKey">排序类型</typeparam>
/// <param name="pageIndex">当前页</param>
/// <param name="pageSize">每页大小</param>
/// <param name="isAsc">是否升序排列</param>
/// <param name="predicate">条件表达式</param>
/// <param name="keySelector">排序表达式</param>
/// <returns></returns>
public Page<T> SearchFor<TKey>(int pageIndex, int pageSize, Expression<Func<T, bool>> predicate, bool isAsc,
Expression<Func<T, TKey>> keySelector)
{
if (pageIndex <= || pageSize <= ) throw new Exception("pageIndex或pageSize不能小于等于0");
var page = new Page<T> { PageIndex = pageIndex, PageSize = pageSize };
var skip = (pageIndex - ) * pageSize;
var able = Entity.AsQueryable().AsNoTracking();
if (predicate == null)
{
var count = Entity.Count();
var query = isAsc
? able.OrderBy(keySelector).Skip(skip).Take(pageSize)
: able.OrderByDescending(keySelector).Skip(skip).Take(pageSize);
page.TotalRows = count;
page.LsList = query.ToList();
page.TotalPages = page.TotalRows / pageSize;
if (page.TotalRows % pageSize != ) page.TotalPages++;
}
else
{
var queryable = able.Where(predicate);
var count = queryable.Count();
var query = isAsc
? queryable.OrderBy(keySelector).Skip(skip).Take(pageSize)
: queryable.OrderByDescending(keySelector).Skip(skip).Take(pageSize);
page.TotalRows = count;
page.LsList = query.ToList();
page.TotalPages = page.TotalRows / pageSize;
if (page.TotalRows % pageSize != ) page.TotalPages++;
}
return page;
}
/// <summary>
/// 获取实体
/// </summary>
/// <param name="id">主键id</param>
/// <returns></returns>
public T GetModelById(object id)
{
return Entity.Find(id);
} /// <summary>
/// 获取实体（条件）
/// </summary>
/// <param name="predicate">条件表达式</param>
/// <returns></returns>
public T GetModel(Expression<Func<T, bool>> predicate)
{
return Entity.FirstOrDefault(predicate);
}
/// <summary>
/// 查询记录数
/// </summary>
/// <param name="predicate"></param>
/// <returns></returns>
public int Count(Expression<Func<T, bool>> predicate)
{
return predicate != null ? Entity.Where(predicate).Count() : Entity.Count();
}
/// <summary>
/// 是否存在
/// </summary>
/// <param name="anyLambda"></param>
/// <returns></returns>
public bool Exist(Expression<Func<T, bool>> anyLambda)
{
return Entity.Any(anyLambda);
}
}
}
分页Page类
using System.Collections.Generic; namespace NetCoreWebApi.Repository.Dto
{
public class Page<T>
{
/// <summary>
/// 当前页
/// </summary>
public int PageIndex { get; set; }
/// <summary>
/// 总页数
/// </summary>
public int TotalPages { get; set; }
/// <summary>
/// 集合总数
/// </summary>
public int TotalRows { get; set; }
/// <summary>
/// 每页项数
/// </summary>
public int PageSize { get; set; }
/// <summary>
/// 集合
/// </summary>
public IList<T> LsList { get; set; }
}
}
二、仓储的泛型的依赖注入。
修改Startup.cs启动类中ConfigureServices方法
public static IContainer ApplicationContainer { get; set; }
/// <summary>
/// //负责注入服务
/// </summary>
/// <param name="services"></param>
/// <returns></returns>
public IServiceProvider ConfigureServices(IServiceCollection services)
{
//获取数据库连接字符串
var connectionStr = Configuration.GetConnectionString("SqlServer");
services.AddDbContext<MyDbContext>
(options => options.UseSqlServer(connectionStr,
e => e.MigrationsAssembly("NetCoreWebApi.Model")));
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
//初始化容器
var builder = new ContainerBuilder();
//管道寄居
builder.Populate(services);
//注册业务
builder.RegisterAssemblyTypes(Assembly.Load("NetCoreWebApi.Repository"), Assembly.Load("NetCoreWebApi.Repository"))
.Where(t => t.Name.EndsWith("Repository"))
.AsImplementedInterfaces();
//注册仓储，所有IRepository接口到Repository的映射
builder.RegisterGeneric(typeof(Repository<>))
//InstancePerDependency：默认模式，每次调用，都会重新实例化对象；每次请求都创建一个新的对象；
.As(typeof(IRepository<>)).InstancePerDependency();
//构造
ApplicationContainer = builder.Build();
//将AutoFac反馈到管道中
return new AutofacServiceProvider(ApplicationContainer);
}三、测试
修改业务层---UserRepository
给泛型类指定ThUser，红色字体是主要更改部分。
using System.Collections.Generic;
using System.Linq;
using NetCoreWebApi.Model.Models;
using NetCoreWebApi.Repository.Interface;
using NetCoreWebApi.Repository.Repository; namespace NetCoreWebApi.Repository.Implement
{
/// <summary>
/// 业务处理
/// </summary>
public class UserRepository:IUserRepository
{
private readonly IRepository<TbUser> _userRepository; /// <summary>
/// 构造函数
/// </summary>
/// <param name="userRepository"></param>
public UserRepository(IRepository<TbUser> userRepository)
{
_userRepository = userRepository;
}
/// <summary>
/// 添加用户
/// </summary>
/// <param name="entity"></param>
/// <returns></returns>
public int Add(TbUser entity)
{
return _userRepository.Add(entity);
}
/// <summary>
/// 删除用户
/// </summary>
/// <param name="entity"></param>
/// <returns></returns>
public int Remove(TbUser entity)
{
return _userRepository.Remove(entity);
}
/// <summary>
/// 查询用户
/// </summary>
/// <returns></returns>
public IList<TbUser> GetAll()
{
return _userRepository.GetAll().ToList();
}
/// <summary>
/// 条件查询
/// </summary>
/// <param name="name">姓名</param>
/// <param name="isAsc">是否正序</param>
/// <param name="pageIndex">页码</param>
/// <param name="pageSize">每页大小</param>
/// <returns></returns>
public object SearchFor(string name, bool isAsc, int pageIndex, int pageSize)
{
//条件表达式
Expression<Func<TbUser, bool>> predicate = e => string.IsNullOrWhiteSpace(name) || e.UserName.Equals(name);
var data = _userRepository.SearchFor(pageIndex, pageSize, predicate, isAsc, e=>e.CreateTime);
return data;
}
}
}
多条件查询
稍微修改下条件查询接口
/// <summary>
/// 条件查询
/// </summary>
/// <param name="name">姓名</param>
/// <param name="name1">姓名1</param>
/// <param name="isAsc">是否正序</param>
/// <param name="pageIndex">页码</param>
/// <param name="pageSize">每页大小</param>
/// <returns></returns>
public object SearchFor(string name, string name1, bool isAsc, int pageIndex, int pageSize)
{
//条件表达式
Expression<Func<TbUser, bool>> predicate = e => (string.IsNullOrWhiteSpace(name) || e.UserName.Equals(name))&&
(string.IsNullOrWhiteSpace(name1)||e.UserName.Equals(name1));
var data = _userRepository.SearchFor(pageIndex, pageSize, predicate, isAsc, e=>e.CreateTime);
return data;
}
运行项目执行接口，可以看到跟之前一样
如果有其他实体只需要改变传入的T就可以了，不需要再重新创建TEntityRepository