C#: asp.net 核心空迁移

Question

我正在尝试从 DatabaseContext 添加迁移但是当我添加一个迁移时，我会像这样生成它为空。我一直在关注这个教程

namespace MovieExampleAppDotNetCore.Migrations
{
    using System;
    using System.Data.Entity.Migrations;

    public partial class ModelMigration : DbMigration
    {
        public override void Up()
        {
        }

        public override void Down()
        {
        }
    }
}

这些是模型、迁移配置、启动和 DatabaseContext

Movie.cs

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Threading.Tasks;

namespace MovieExampleAppDotNetCore.Models
{
    public class Movie
    {   
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int MovieId { get; set; }
        public String Name { get; set; }

        [Column(TypeName = "datetime2")]
        public DateTime? DateCreated { get; set; }
    }
}

Customer.cs

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Threading.Tasks;

namespace MovieExampleAppDotNetCore.Models
{
    public class Customer
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int CustomerId { get; set; }
        public string Name { get; set; }
        public string LastName { get; set; }
        public bool IsCreated { get; set; }
        public int MaxMovies { get; set; }

        [Column(TypeName = "datetime2")]
        public DateTime Created { get; set; }

        [Column(TypeName = "datetime2")]
        public DateTime? LastEdited { get; set; }


    }
}

Configuration.cs

namespace MovieExampleAppDotNetCore.Migrations
{
    using System;
    using System.Data.Entity;
    using System.Data.Entity.Migrations;
    using System.Linq;

    internal sealed class Configuration : DbMigrationsConfiguration<MovieExampleApp.Persistention.DatabaseContext>
    {
        public Configuration()
        {
            AutomaticMigrationsEnabled = true;
        }

        protected override void Seed(MovieExampleApp.Persistention.DatabaseContext context)
        {

        //  This method will be called after migrating to the latest version.

        //  You can use the DbSet<T>.AddOrUpdate() helper extension method
        //  to avoid creating duplicate seed data.
    }
}

}

DatabaseContext.cs

using Microsoft.EntityFrameworkCore;
using MovieExampleAppDotNetCore.Models;
using System.Data.Entity;


namespace MovieExampleApp.Persistention
{
    public class DatabaseContext : System.Data.Entity.DbContext
    {
        public DatabaseContext() : base("main")
        {
            //Database.Initialize(true);
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
        }

        public Microsoft.EntityFrameworkCore.DbSet<Movie> Movies { get; set; }
        public Microsoft.EntityFrameworkCore.DbSet<Customer> Customers { get; set; }
    }
}

Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Formatters;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;
using MovieExampleApp.Persistention;
using System.Linq;

namespace MovieExampleAppDotNetCore
{
    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)
        {

            services.AddDbContext<DatabaseContext>(
                        options => options.UseSqlServer(Configuration.GetConnectionString("DatabaseContext")));

            services.AddControllersWithViews().AddNewtonsoftJson();

            services.AddControllersWithViews(options =>
            {
                options.InputFormatters.Insert(0, GetJsonPatchInputFormatter());
            });

        }

        private static NewtonsoftJsonPatchInputFormatter GetJsonPatchInputFormatter()
        {
            var builder = new ServiceCollection()
                .AddLogging()
                .AddMvc()
                .AddNewtonsoftJson()
                .Services.BuildServiceProvider();

            return builder
                .GetRequiredService<IOptions<MvcOptions>>()
                .Value
                .InputFormatters
                .OfType<NewtonsoftJsonPatchInputFormatter>()
                .First();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

我希望有人能告诉我我做错了什么。

Answer 1

使用这个；添加迁移 migration1 在调用 update-database

之前

Answer 2

据我所知，您不需要像使用 [Key] 那样使用 [DatabaseGenerated(DatabaseGeneratedOption.Identity)] - 这足以在属性上设置主键。

试试这个方法：

首先，我将通过在 Package-Manger-Console 中键入来删除空迁移：

删除迁移

我还假设您没有任何其他迁移，您实际上已经添加了这些您现在要添加的模型。

然后：

ApplicationDbContext Class:

public class ApplicationDbContext : DbContext
{
            public ApplicationDbContext(DbContextOptions<ApplicationDbContext> context) : base(context)
    {
    }

    public DbSet<Movie> Movies { get; set; }
    public DbSet<Customer> Customers { get; set; }
}

我假设您在启动时已准备好更新数据库的所有内容，但只是提一下：

Startup:

    public void ConfigureServices(IServiceCollection services)
    {

     //some code...
            services.AddDbContext<ApplicationDbContext>(
            options => options.UseSqlServer(Configuration.GetConnectionString("DevConnection")));
    }

当然还要更新 appsettings.json 中的连接字符串以反映连接名称：

  "ConnectionStrings": {
"DevConnection": "Server=SERVER; Database=DB; Trusted_Connection=True; MultipleActiveResultSets=True;",

 }

然后在 Package-Manager-Console 中输入：add-migration [Migration Name]

Answer 3

我找到了问题的答案。我正在使用 using System.Data.Entity; 而不是 using Microsoft.EntityFrameworkCore;

这是工作代码

DatabaseContext.cs

using Microsoft.EntityFrameworkCore;
using MovieExampleAppDotNetCore.Models;


namespace MovieExampleApp.Persistention
{
    public class DatabaseContext : DbContext
    {
        public DatabaseContext(DbContextOptions<DatabaseContext> context) : base(context)
        {
            //Database.Initialize(true);
        }

        public DatabaseContext()
        {
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
        }

        public DbSet<Movie> Movies { get; set; }
        public DbSet<Customer> Customers { get; set; }
    }
}

Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Formatters;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Options;
using Microsoft.EntityFrameworkCore.SqlServer;
using System.Linq;
using MovieExampleApp.Persistention;

namespace MovieExampleAppDotNetCore
{
    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)
        {
            services.AddMvc();
            services.AddDbContext<DatabaseContext>(
            options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));


            services.AddControllersWithViews().AddNewtonsoftJson();

            services.AddControllersWithViews(options =>
            {
                options.InputFormatters.Insert(0, GetJsonPatchInputFormatter());
            });

        }

        private static NewtonsoftJsonPatchInputFormatter GetJsonPatchInputFormatter()
        {
            var builder = new ServiceCollection()
                .AddLogging()
                .AddMvc()
                .AddNewtonsoftJson()
                .Services.BuildServiceProvider();

            return builder
                .GetRequiredService<IOptions<MvcOptions>>()
                .Value
                .InputFormatters
                .OfType<NewtonsoftJsonPatchInputFormatter>()
                .First();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

C#: asp.net 核心空迁移

C#: asp.net CORE empty Migration

c#

ef-code-first

entity-framework-migrations

asp.net-core