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Unable to determine the relationship represented by navigation property ASP.NET core 2.0 Entity Framework


Unable to determine the relationship represented by navigation property ASP.NET core 2.0 Entity Framework

By : Huynh Nam Truong
Date : November 21 2020, 03:00 PM
I hope this helps . As what I commented earlier that there are many differences between Entity Framework and Entity Framework Core 2.0, I don't think you can just take the models generated from Entity Framework and run Code First with Entity Framework Core 2.0.
From the models described, it looks like MessageMeta and EnumMeta has many-to-many relationship.
code :
using System.Collections.Generic;

namespace DL.SO.MessageEnum.Web.UI.Models
{
    public class MessageMeta
    {
        public int MsgId { get; set; }

        public List<MessageEnum> EnumMetas { get; set; }
    }
}
using System.Collections.Generic;

namespace DL.SO.MessageEnum.Web.UI.Models
{
    public class EnumMeta
    {
        public int EnumId { get; set; }
        public bool IsFlag { get; set; }

        public List<MessageEnum> MessageMetas { get; set; }
    }
}
namespace DL.SO.MessageEnum.Web.UI.Models
{
    public class MessageEnum
    {
        public int MessageMetaId { get; set; }
        public MessageMeta MessageMeta { get; set; }

        public int EnumMetaId { get; set; }
        public EnumMeta EnumMeta { get; set; }
    }
}
using Microsoft.EntityFrameworkCore;

namespace DL.SO.MessageEnum.Web.UI.Models
{
    public class AppDbContext : DbContext
    {
        public AppDbContext(DbContextOptions<AppDbContext> options): base(options) { }

        public DbSet<MessageMeta> Messages { get; set; }
        public DbSet<EnumMeta> Enums { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<MessageMeta>()
                .HasKey(x => x.MsgId);

            modelBuilder.Entity<EnumMeta>()
                .HasKey(x => x.EnumId);

            modelBuilder.Entity<MessageEnum>()
                .HasKey(x => new { x.MessageMetaId, x.EnumMetaId });
            modelBuilder.Entity<MessageEnum>()
                .HasOne(x => x.MessageMeta)
                .WithMany(m => m.EnumMetas)
                .HasForeignKey(x => x.MessageMetaId);
            modelBuilder.Entity<MessageEnum>()
                .HasOne(x => x.EnumMeta)
                .WithMany(e => e.MessageMetas)
                .HasForeignKey(x => x.EnumMetaId);
        }
    }
}
{
  "ConnectionStrings": {
    "AppDbConnection": "Data Source=.\\SQLEXPRESS;Initial Catalog=SO.MessageEnum;Integrated Security=True;MultipleActiveResultSets=False;"
  },
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Warning"
    }
  }
}
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using DL.SO.MessageEnum.Web.UI.Models;
using Microsoft.EntityFrameworkCore;

namespace DL.SO.MessageEnum.Web.UI
{
    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)
        {
            string dbConnectionString = Configuration.GetConnectionString("AppDbConnection");

            services.AddDbContext<AppDbContext>(options =>
                options.UseSqlServer(dbConnectionString)
            );

            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseStaticFiles();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}
Add-Migration Init
Update-Database


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Unable to determine the relationship represented by navigation property

Unable to determine the relationship represented by navigation property


By : nunny
Date : March 29 2020, 07:55 AM
this will help As explained in this answer, I would need to duplicate the shared relationships.
When using DbContext2, the relationships between User and Group aren't defined.
EF Unable to determine the relationship represented by navigation property

EF Unable to determine the relationship represented by navigation property


By : user2173045
Date : October 21 2020, 08:10 PM
I hope this helps you .
The code works fine if i remove DbQuery but i want it there so i can Query on that data without doing an Include from a workflow, and still be sure that no changes are made directly inside the step.
How to fix 'Unable to determine the relationship represented by navigation property' error in Entity Framework

How to fix 'Unable to determine the relationship represented by navigation property' error in Entity Framework


By : Jiganesh Ganda Lal
Date : March 29 2020, 07:55 AM
hope this fix your issue When I try to register a user on my .NET Core 2.1 website (using identity) I get the following error: , UPDATE
You have multiple options here:
code :
public partial class City
{
    public City()
    {           
        Connections = new HashSet<Connection>();
    }

    public int Id { get; set; }
    public string Name { get; set; }
    public string Country { get; set; }

    public ICollection<Connection> Connections { get; set; }
}
public partial class Connection
{
    public Connection()
    {
    }

    public int Id { get; set; }

    public int StartCityId { get; set; }
    public int EndCityId { get; set; }

    public int AantalMinuten { get; set; }
    public double Prijs { get; set; }     
}
modelBuilder.Entity<City>().HasMany(city => city.Connections)
                           .WithRequired().HasForeignKey(con => con.EndCityId);

modelBuilder.Entity<City>().HasMany(city => city.Connections)
                           .WithRequired().HasForeignKey(con => con.StartCityId);
public partial class City
{
    public City()
    {           
        Connections = new HashSet<Connection>();
    }

    public int Id { get; set; }
    public string Name { get; set; }
    public string Country { get; set; }

    public ICollection<Connection> Connections { get; set; }
}
public partial class Connection
{
    public Connection()
    {
    }

    public int Id { get; set; }

    public virtual ICollection<City> Cities { get; set; }

    public int AantalMinuten { get; set; }
    public double Prijs { get; set; }     
}
Unable to determine the relationship represented by navigation property 'JToken.Parent' of type 'JContainer'

Unable to determine the relationship represented by navigation property 'JToken.Parent' of type 'JContainer'


By : user2831730
Date : March 29 2020, 07:55 AM
I wish this helpful for you I finally found that by myself. As the error message has mentioned, I should add a [NotMapped] attribute before the properties which is not in my table fields.
EF Core unable to determine relationship represented by foreign keys in abstract class

EF Core unable to determine relationship represented by foreign keys in abstract class


By : PoHsiang
Date : March 29 2020, 07:55 AM
With these it helps
A potential additional complication is that the User class also has a property of class Department, which is unrelated to the CreatedBy and ModifiedBy properties on Department.
code :
modelBuilder.Entity<User>()
    .HasOne(e => e.Department)
    .WithMany();

modelBuilder.Entity<Department>()
    .HasOne(e => e.CreatedBy)
    .WithMany();

modelBuilder.Entity<Department>()
    .HasOne(e => e.ModifiedBy)
    .WithMany();
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