c# – 使用EF和Dot Net Core 1(PostgreSQL数据库)生成迁移时出错

我遵循了damienbod( https://damienbod.com/2016/01/11/asp-net-5-with-postgresql-and-entity-framework-7/)的教程.我设法获得了与PostgreSql数据库的连接,并创建了EntityMigration历史表,DataEventRecord表和SourceInfo表.总共有三个项目(Postgre需要两个项目,第三个是我的实际项目)：DataAccessPostgreSqlProvider,DomainModel和iConnect.

我在下面创建了一个Model,代码,然后执行：add-migration NestProtectDevices -Context NestProtectDevices

我必须指定-Context或者我得到一个错误,如果我指定DomainModelPostgreSqlContext的-Context,它只会生成一个空的迁移文件(而不是从我的模型生成一个).这就是我将-Context指定为Model名称的原因.下面是模型的代码和我得到的错误.让我知道是否需要任何其他代码来帮助调试.

using DataAccessPostgreSqlProvider;
using DomainModel;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using DomainModel.Model;

namespace iConnect.Models.Nest
{
    public class NestProtectDevices : DomainModelPostgreSqlContext
    {
        public NestProtectDevices(DbContextOptions<DomainModelPostgreSqlContext> options) : base(options)
        {
        }

        public long DeviceId { get; set; }
        public long UserId { get; set; }
        public int CompanyId { get; set; }
        public long StructureId { get; set; }
        public long WhereId { get; set; }
        public string Name { get; set; }
        public string NameLong { get; set; }
        public bool IsOnline { get; set; }
        public int BatteryHealth { get; set; }
        public int CoAlarmState { get; set; }
        public int SmokeAlarmState { get; set; }
        public string UiColorState { get; set; }
        public bool IsManualTestActive { get; set; }
        public DateTime LastManualTestTime { get; set; }
        public DateTime Timestamp { get; set;}
    }
}

命令有错误：

PM> add-migration NestProtectDevices -Context NestProtectDevices
No parameterless constructor was found on 'NestProtectDevices'. Either add a parameterless constructor to 'NestProtectDevices' or add an implementation of 'IDbContextFactory<NestProtectDevices>' in the same assembly as 'NestProtectDevices'.

using DataAccessPostgreSqlProvider;
    using DomainModel;
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Threading.Tasks;
    using Microsoft.EntityFrameworkCore;
    using DomainModel.Model;

    namespace iConnect.Models.Nest
    {
        public class NestProtectDevices : DomainModelPostgreSqlContext
        {
            public NestProtectDevices(DbContextOptions<DomainModelPostgreSqlContext> options) : base(options)
            {
            }
            public DbSet<Device> Devices { get; set; }

        }
public class Device
{
            public long DeviceId { get; set; }
            public long UserId { get; set; }
            public int CompanyId { get; set; }
            public long StructureId { get; set; }
            public long WhereId { get; set; }
            public string Name { get; set; }
            public string NameLong { get; set; }
            public bool IsOnline { get; set; }
            public int BatteryHealth { get; set; }
            public int CoAlarmState { get; set; }
            public int SmokeAlarmState { get; set; }
            public string UiColorState { get; set; }
            public bool IsManualTestActive { get; set; }
            public DateTime LastManualTestTime { get; set; }
            public DateTime Timestamp { get; set;}
  }
}