Question

我正在尝试做一个简单的MVC项目。我们的想法是从数据库中选择信息并将其显示在地图上。这是以前未写入MVC的作业的升级/替换。需要新功能，MVC应该易于（维护）。

数据库是供应商数据库，我不做任何更改。我添加了4个视图：

vwMapsDrivers驱动程序详细信息
vwMapsVehicles车辆详情
vwMapsIncidents事件详情
vwMapsLogs日志条目

基本计划是列出事件，附加的驾驶员和车辆信息，以及从事件开始到事件结束的一系列日志（+任何一个阈值）。

这是 MainContext 类

using System;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;

namespace MapsMVC.Models
{
    public class MainContext : DbContext
    {
        public DbSet<VehicleModel> Vehicles { get; set; }

        public DbSet<IncidentModel> Incidents { get; set; }

        public DbSet<DriverModel> Drivers { get; set; }

        public DbSet<LogsModel> Logs { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<VehicleModel>().ToTable("vwMapsVehicles");
            modelBuilder.Entity<IncidentModel>().ToTable("vwMapsIncidents");
            modelBuilder.Entity<DriverModel>().ToTable("vwMapsDrivers");
            modelBuilder.Entity<LogsModel>().ToTable("vwMapsLogs");

            base.OnModelCreating(modelBuilder);
        }
    }

}

这是 IncidentModel 类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using DataAnnotationsExtensions;

namespace CtrackMapsMVC.Models
{
    public class IncidentModel
    {
        [Key]
        [Integer]
        [Min(0)]
        [Display(Name = "Incident Id")]
        public int IncidentId { get; set; }

        [Integer]
        [ForeignKey("Vehicles")]
        [Display(Name = "Vehicle Id")]
        public string NodeId { get; set; }

        [DataType(DataType.DateTime)]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd HH:mm:ss}", ApplyFormatInEditMode = true)]
        [Display(Name = "Incident Start")]
        public DateTime IncidentStart { get; set; }

        [DataType(DataType.DateTime)]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd HH:mm:ss}", ApplyFormatInEditMode = true)]
        [Display(Name = "Incident End")]
        public DateTime IncidentEnd { get; set; }

        [Required]
        [DataType(DataType.Text)]
        [Display(Name = "Location")]
        public string Location { get; set; }

        [Required]
        [DataType(DataType.Text)]
        [Display(Name = "Incident Type")]
        public string IncidentType { get; set; }

        [Integer]
        [Min(0)]
        [ForeignKey("Logs")]
        [Display(Name = "First Log Id")]
        public int FirstLogId { get; set; }

        [Integer]
        [Min(0)]
        [ForeignKey("Logs")]
        [Display(Name = "Last Log Id")]
        public int LastLogId { get; set; }

        [Integer]
        [Min(0)]
        [ForeignKey("Drivers")]
        [DisplayFormat(NullDisplayText = "No Driver")]
        [Display(Name = "Driver Node Id")]
        public int DriverNodeId { get; set; }

        public virtual VehicleModel Vehicle { get; set; }
        public virtual DriverModel Driver { get; set; }
        public virtual ICollection<LogsModel> Logs { get; set; }
    }
}

这是 VehicleModel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;
using DataAnnotationsExtensions;

namespace CtrackMapsMVC.Models
{
    public class VehicleModel
    {
        [Key]
        [Integer]
        [Min(0)]
        [Editable(false)]
        [Display(Name = "Node Id")]
        public int NodeId { get; set; }

        [Required]
        [DataType(DataType.Text)]
        [Editable(false)]
        [Display(Name = "Vehicle Name")]
        public string VehicleName { get; set; }

        [DataType(DataType.Text)]
        [Editable(false)]
        [Display(Name = "Vehicle Description")]
        public string VehicleDescription { get; set; }

        [DataType(DataType.Text)]
        [Editable(false)]
        [Display(Name = "Cellnumber")]
        public string Cellnumber { get; set; }

        [DataType(DataType.DateTime)]
        [Editable(false)]
        [Display(Name = "Last Received")]
        public DateTime LastReceived { get; set; }

        [DataType(DataType.Text)]
        [Editable(false)]
        [Display(Name = "Unit Type")]
        public string NodeTypeDesc { get; set; }

        [DataType(DataType.Text)]
        [Editable(false)]
        [Display(Name = "Site Code")]
        public string SiteCode { get; set; }

    }


}

LogsModel 和 DriverModel 非常简单。

网站编译没有问题，控制器是默认生成的样板文件。还会生成视图，但会删除编辑/删除页面，索引中的链接引用也会被删除。

主页加载。当尝试加载/ Vehicle / Index时，我得到以下异常：

属性＆＃39; NodeId＆＃39;上的ForeignKeyAttribute on type＆＃39; CtrackMapsMVC.Models.IncidentModel＆＃39;无效。导航属性＆＃39; Vehicles＆＃39;在依赖类型＆＃39; CtrackMapsMVC.Models.IncidentModel＆＃39;中找不到。 Name值应该是有效的导航属性名称。

我的外键申报出了什么问题？我该如何解决？有些阅读暗示它不会起作用，因为SQL VIews实际上没有FK关系（不可能定义）。有延伸会有所帮助吗？对视图进行编码确实不常见吗？

Answer 1

您在此处设置的属性：[ForeignKey("Vehicles")]是您设置为“车辆”的导航属性，但您包含public virtual VehicleModel Vehicle { get; set; }，这是“车辆”而不是“车辆”。

价： http://peterkellner.net/2012/04/07/gaining-some-control-back-from-microsofts-entity-framework-code-first-name-your-own-foreign-keys/

Answer 2

这是基于EntityTypeConfiguration<>的映射有用的地方。给你一些编译时间的帮助：

internal class IncidentMap : EntityTypeConfiguration<IncidentModel>
{
    public IncidentMap()
    {
        HasKey(x => x.IncidentId);
        ToTable("vwMapsIncidents");

        HasRequired(m => m.Vehicle)
            .WithMany()
            .HasForeignKey(m => m.NodeID);

        //or if you added a 'Incidents' property on 'Vehicle'

        HasRequired(m => m.Vehicle)
            .WithMany(m => m.Incidents)
            .HasForeignKey(m => m.NodeID);
    }
}

用法：

public class MainContext : DbContext
{
    public DbSet<VehicleModel> Vehicles { get; set; }
    public DbSet<IncidentModel> Incidents { get; set; }
    public DbSet<DriverModel> Drivers { get; set; }
    public DbSet<LogsModel> Logs { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Configurations.Add(new IncidentMap());
        modelBuilder.Configurations.Add(new VehicleMap());
        modelBuilder.Configurations.Add(new DriverMap());
        modelBuilder.Configurations.Add(new LogsMap());

        base.OnModelCreating(modelBuilder);
    }
}

然后从模型中删除所有[ForeignKey]属性。

祝你好运......

Docs for EntityTypeConfiguration

MVC模型导航链接

2 个答案: