【发布时间】：2020-02-20 11:40:50
【问题描述】：
我正在尝试添加来自 DatabaseContext 的迁移
但是当我添加迁移时，我会像这样将其生成为空。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。
【问题讨论】：
-
如果它正在生成一个空迁移，那么您的数据库可能已经被标记为具有当前迁移。检查数据库中的迁移表，确认最新迁移是否与上述迁移不同。
-
我目前在 Server Management Studio 中没有表。所以这不是问题。
-
有没有桌子都没有关系。如果您之前创建了迁移然后删除了数据库，则之前的迁移（和快照仍然存在于您的迁移文件文件夹中。EF Core 将您当前的模型与您的
DatabaseContextModelSnapshot.cs匹配。仅当您的当前模型和您的迁移具有任何值的上一个快照 -
我删除了迁移文件夹更新的数据库并启用了迁移。但是当我添加迁移时，它仍然是空的。
-
如果您已经完成了上述操作，那么您的数据库已经是最新的了。对模型进行更改后，将触发带有更改的迁移。尝试将属性添加到您的客户实体并尝试另一次迁移，您应该会在 Up 中看到添加的属性，而在 Down 中将其删除。
标签： c# asp.net-core ef-code-first entity-framework-migrations