ASP .NET Razor(.NET Core 5.0)中使用Session和Entity Framework Core以及WPF SelfHost

• 前言
• Session
• • 使用Session
  • Session中存取对象
• 使用Entity Framework Core
• WPF SelfHost

前段时间将网站项目迁移至.Net Core平台时遇到不少问题，翻了一下搜索引擎，很多都是基于Core 2.1版本的解决方案，某些在5.0上已经不适用了，于是写下这篇笔记。

在Asp .Net Core中添加Session支持很简单，我们只需要在Startup.cs中的ConfigureServices和Configure中增加如下内容即可。

public void ConfigureServices(IServiceCollection services)
        {
        ......
        services.AddDistributedMemoryCache();
         services.AddSession(options =>
            {

                options.IdleTimeout = TimeSpan.FromMinutes(5);
                options.Cookie.HttpOnly = true;
                options.Cookie.IsEssential = true;
            });
            ......
        }
 public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            ......
            app.UseSession();
            ......
        }

注意services.AddDistributedMemoryCache()，此处你可以根据自己项目的需求更改为AddDistributedRedisCache或者AddDistributedSqlServerCache，具体参看MSDN中关于缓存的描述。
缓存

Razor页面中

HttpContext.Session.SetString("headPic", "1.jpg");
string headpic = HttpContext.Session.GetString("headPic");

布局页中

@inject Microsoft.AspNetCore.Http.IHttpContextAccessor  _httpContextAccessor;
@{
    _httpContextAccessor.HttpContext.Session.SetString("headPic", "1.jpg");
    string headpic = _httpContextAccessor.HttpContext.Session.GetString("headPic");
}

API 控制器中

public partial class ApiController : ControllerBase
    {
        private IHttpContextAccessor _accessor;
        public ApiController(IHttpContextAccessor accessor)
        {
            _accessor = accessor;
        }
        [HttpPost]
        public async Task> dosth(int id)
        {
           string name=  _accessor.HttpContext.Session.GetString("name");
           await ........
        }
    }

public static class SessionExtensions
    {
        public static void Set(this ISession session, string key, T value)
        {
            Newtonsoft.Json.Converters.IsoDateTimeConverter timeConverter = new Newtonsoft.Json.Converters.IsoDateTimeConverter();
            timeConverter.DateTimeFormat = "yyyy/MM/dd HH:mm";
            string jsonData = Newtonsoft.Json.JsonConvert.SerializeObject(value, Newtonsoft.Json.Formatting.Indented, timeConverter);
            session.SetString(key, jsonData);
        }

        public static T Get(this ISession session, string key)
        {
            var value = session.GetString(key);

            return value == null ? default : Newtonsoft.Json.JsonConvert.DeserializeObject(value);
        }
    }

使用很简单

Session.Set>("Rights", new List());//设置值
List cr = Session.Get>("Rights");//取值

使用NuGet安装如下包：
Microsoft.EntityFrameworkCore
Microsoft.EntityFrameworkCore.SqlServer
Microsoft.EntityFrameworkCore.Tools
转到程序包管理控制台，输入：

Scaffold-DbContext -Connection =="sql连接字符串，密码中特殊字符要在前面加`"== -Provider Microsoft.EntityFrameworkCore.SqlServer -OutputDir ==datas== -Force -Context ==dataEntities== -UseDatabaseNames -Project ==yourproject==

等待操作完成后，就可以在设置的OutputDir文件夹中看到建好的数据模型了。如果要更新数据，只需要重新运行一次上面的代码即可。
接下来在Startup的ConfigureServices中加入如下代码

services.AddDbContext(options =>options.UseSqlServer("sql连接字符串"));

直接给代码

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.OpenApi.Models;

 public static class HostBuilder
    {
        public static IHost webHost;
         
        public static void start()
        { 
           webHost = Host.CreateDefaultBuilder()
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseUrls("http://" + ip + ":" + serverport).UseStartup();
                }).Build();
            webHost.StartAsync(); 
        }
        public static void stop()
        { 
            webHost.StopAsync();
            webHost.Dispose();
        }
    }
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; } 
        public void ConfigureServices(IServiceCollection services)
        {

            services.AddControllers();
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "WebApplication1", Version = "v1" });
            });
        } 
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "WebApplication1 v1"));
            }
            app.UseCors(
          options => options.WithOrigins("*").AllowAnyMethod()
      );
            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }

如果想用WPF宿主已经做好的网站，首先添加网站项目引用，然后修改HostBuilder的start如下

 webHost = Host.CreateDefaultBuilder()
                       .ConfigureWebHostDefaults(builder => builder.UseUrls("http://" +ip + ":" + port).UseStartup<项目命名空间.Startup>())
                       .ConfigureAppConfiguration(configBuilder =>
                       {
                           configBuilder.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
                           configBuilder.AddEnvironmentVariables();
                       })
                       .Build();
            webHost.StartAsync();