现有数据库的下拉列表 [Asp.Net Core 2.0 MVC 实体框架]答案

【问题标题】：DropDownList from Existing DataBase [Asp.Net Core 2.0 MVC Enity Framework]现有数据库的下拉列表 [Asp.Net Core 2.0 MVC 实体框架]
【发布时间】：2019-01-04 09:42:13
【问题描述】：

希望你能帮帮我我要绑定 DropDownList 并从现有数据库中获取数据。 Visual Studio 没有显示错误，但是当我运行应用程序时，它会告诉我迁移我的数据库，即使我已经迁移了它。这是我的代码。

创建.cs

<div class="form-group">
    <label asp-for="DomWasAccNo" class="control-label"></label>
    <select asp-for="DomWasAccNo"
                    class="form-control"
                    asp-items="@(new SelectList(@ViewBag.ListOfConsumer, "AccountNo","AccountNo"))"></select>
    <span asp-validation-for="DomWasAccNo" class="text-danger"></span>
</div>

LibCustomers.cs 此部分是使用此 CLI 命令“dotnet ef dbcontext scaffold "Server=192.168.1.28;Database=SBMA_TUBS;User Id=sa;" Microsoft.EntityFrameworkCore.SqlServer -d -o Model -c "CustomerDbContext"

自动生成的

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace WWFS.Models
{
    [Table("LIB_CONSUMERS")]
    public partial class LibConsumers
    {
        [Column("account_no")]
        [StringLength(15)]
        public string AccountNo { get; set; }

        [Column("consumer_name")]
        [StringLength(255)]
        public string ConsumerName { get; set; }

        [Column("address")]
        [StringLength(255)]
        public string Address { get; set; }
    }
}

Controller.cs

 List<LibConsumers> libConsumers = new List<LibConsumers>();

 libConsumers = (from cons in _context.LibConsumers
                        select cons).ToList();
 libConsumers.Insert(0, new LibConsumers { AccountNo = "Select" });

 ViewBag.ListOfConsumer = libConsumers;

DomesticWaste.cs

using Microsoft.EntityFrameworkCore;

namespace WWFS.Models
{
    public class DomesticWasteDbContext : DbContext
    {
        public DomesticWasteDbContext(DbContextOptions<DomesticWasteDbContext> options)
        : base(options)
    {
    }

    public DbSet<WWFS.Models.DomesticWaste> DomesticWastes { get; set; }
    public DbSet<WWFS.Models.Location> Locations { get; set;}
    public DbSet<WWFS.Models.Contractor> Contractors  { get; set; }
    public DbSet<WWFS.Models.LibConsumers> LibConsumers { get; set; }
}

}

CustomerDbContext.cs 此部分是使用此 CLI 命令“dotnet ef dbcontext scaffold "Server=192.168.1.28;Database=SBMA_TUBS;User Id=sa;" Microsoft.EntityFrameworkCore.SqlServer -d -o Model -c "CustomerDbContext"

自动生成的

using System;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata;

namespace WWFS.Models
{
    public partial class CustomerDbContext : DbContext
    {
    public virtual DbSet<LibConsumers> LibConsumers { get; set; }
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
            optionsBuilder.UseSqlServer(@"Server=192.168.1.28;Database=SBMA_TUBS;User Id=sa;");
        }
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<LibConsumers>(entity =>
        {
            entity.Property(e => e.AccountNo).ValueGeneratedNever();
            entity.Property(e => e.ConsumerName).ValueGeneratedNever();
            entity.Property(e => e.Address).ValueGeneratedNever();
        });
    }
}

}

【问题讨论】：

那么发生了什么？你有错误吗？
错误是InvalidOperationException: The entity type 'LibConsumers' requires a primary key to be defined.

标签： entity-framework asp.net-core-mvc asp.net-core-2.0

【解决方案1】：

我认为没有人能回答这个问题。

【讨论】：