[EF Core]数据迁移（二）

摘要

在实际项目中，大多都需要对业务逻辑以及操作数据库的逻辑进行分成操作，这个时候该如何进行数据的迁移呢？

步骤

上篇文章：EF Core数据迁移操作

比如，我们将数据上下文放在了Data层。

看一下BlogContext内容如下：

 public class BlogContext : DbContext
    {

        public BlogContext(DbContextOptions options) : base(options)
        {
        }
        public DbSet<User> Users { set; get; }
      
    }

在appsetting中配置连接字符串

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=localhost;database=MyBlogDb;uid=root;pwd=abcd;"
  },
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Warning"
    }
  }
}

在StartUp启动类中，做如下操作：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Wolfy.Blog.Data;

namespace Wolfy.Blog
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;

        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            string connStr = Configuration.GetConnectionString("DefaultConnection");
            services.AddDbContext<BlogContext>(options => options.UseMySQL(connStr,
                opt => opt.MigrationsAssembly("Wolfy.Blog")));
            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseStaticFiles();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

可以看到上面可以指定迁移程序集

  //
        // 摘要:
        //     Configures the assembly where migrations are maintained for this context.
        //
        // 参数:
        //   assemblyName:
        //     The name of the assembly.
        //
        // 返回结果:
        //     The same builder instance so that multiple calls can be chained.
        public virtual TBuilder MigrationsAssembly([CanBeNullAttribute] string assemblyName);

大概意思是配置数据迁移保持的程序集。

总结

一个简单的用法，遇到了，就记录一下，希望对你有所帮助