EF入门

最新推荐文章于 2023-04-26 14:42:26 发布

原创最新推荐文章于 2023-04-26 14:42:26 发布 · 1k 阅读

0 ·

CC 4.0 BY-SA版权

本文介绍如何使用 Entity Framework Core 进行数据库操作，包括安装配置、基本查询、更新及删除等常见操作。同时展示了如何利用 EF 的扩展功能进行更复杂的查询，并提供了遍历输入参数修改旧数据的方法。

安装ef，需要先下载连个链接工具

mysql：

http://dev.mysql.com/downloads/windows/installer/

Connector/Net：

http://dev.mysql.com/downloads/connector/net/

MySQL for Visual Studio：

http://dev.mysql.com/downloads/windows/visualstudio/

[System.Web.Http.Description.ResponseType(typeof(products))]//设置返回值类型

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace EFTest
{
    using System.Data.Entity;
    using System.Runtime.CompilerServices;

    using EFTest.Models;

    class Program
    {
        private static readonly laojiahenanContext dbContext = new laojiahenanContext();
        static void Main(string[] args)
        {
            //var userList = dbContext.yf_user.ToList();
            //foreach (var user in userList)
            //{
            //    System.Console.WriteLine(user.userPhone);
            //}

            //var addUser = dbContext.yf_user.FirstOrDefault(u => u.userPhone == "15286819573");


            dbContext.Database.Log = Console.WriteLine;
            var query = (from user in dbContext.yf_user//.Where(u=>u.userPhone=="15286819572")
                         join community in dbContext.yf_community on user.communityId equals community.id
                         orderby user.userId descending 
                        
                        select new { user, community }).Skip(1).Take(2);

           

            var list = query.ToList();

            foreach (var q in query)
            {
                
                string communityName =string.Empty;
                string userPhone = string.Empty;

                if (q.community != null)
                {
                    communityName = q.community.communityName;
                }

                
                if (q.user != null)
                {
                    userPhone = q.user.userPhone;
                }

                System.Console.WriteLine("{0}---{1}", communityName, userPhone);
            }


            //if (addUser == null)
            //{
            //    dbContext.yf_user.Add(new yf_user() { userPhone = "15286819573", userPass = "123456" });
            //    dbContext.SaveChanges();
            //}
            //else
            //{
            //    //addUser.userName = "杨帆";
            //    //System.Console.WriteLine(addUser.userName);
            //    dbContext.yf_user.Remove(addUser);
            //    dbContext.SaveChanges();
            //}

           

            Console.ReadLine();
        }
    }
}

左关联
 var query = (from user in dbContext.yf_user.Where(u=>u.userId==UserId)
                         join com2 in dbContext.yf_community
                         on user.communityId equals com2.id into JoinedEmpDept
                         from com in JoinedEmpDept.DefaultIfEmpty()
                         select new
                         {
                             user.userId,
                             user.userName,
                             user.userPhoto,
                             user.sex,
                             user.userPhone,
                             user.communityId,
                             user.createTime,
                             user.note,
                             user.isEnable,
                             com.communityName
                         }).FirstOrDefault();

Mode1.demx设置自动类注释和属性注释

tt文件中设置属性注释：

	string summary=string.Empty;
    var simpleProperties = typeMapper.GetSimpleProperties(entity);
    if (simpleProperties.Any())
    {
        foreach (var edmProperty in simpleProperties)
        {
          if (edmProperty.Documentation != null && edmProperty.Documentation.Summary != null)
          {
             summary=edmProperty.Documentation.Summary;
          }
          else
          {
            summary="";
          }
#>
    /// <summary>
    /// <#=summary#>
    /// </summary>
    <#=codeStringGenerator.Property(edmProperty)#>
<#
        }
    }

遍历input中不为空的字段，修改到oldData中，input和oldData必须为同一种Class

//遍历入参的类.找出修改了哪些类型
                foreach (PropertyInfo p in input.GetType().GetProperties())
                {
                    //value不为空
                    if (p.GetValue(input) != null)
                    {
                        //在数据库中找出的数据类中查找并setValue该值
                        PropertyInfo propertyName = typeof(products).GetProperty(p.Name);
                        propertyName.SetValue(oldData, p.GetValue(input), null);
                    }
                }

EF扩展库

1.EntityFramework-Plus http://entityframework-plus.net/

2.EntityFramework.Utilities http://www.jianshu.com/p/dff3c684a0e4