带有实体框架的ASP.NET核心多对多不起作用

Question

I have two models, and a model to connect the two.

Organization model:

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

namespace Verbonding.Models
{
    public class Organization
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public ICollection<OrganizationApplicationUser> OrganizationApplicationUsers { get; set; }

        public Organization()
        {
            IsActive = true;
            IsBlocked = false;
            DateCreated = DateTime.Now;
            DateUpdated = DateTime.Now;
        }

        public ApplicationUser AddUser(ApplicationUser user)
        {
            OrganizationApplicationUser ou = new OrganizationApplicationUser { ApplicationUser = user, Organization = this };

            OrganizationApplicationUsers.Add(ou);
            return user;
        }
    }
}

ApplicationUser model:

using System;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using System.Linq;

namespace Verbonding.Models
{
    public class ApplicationUser : IdentityUser
    {
        public bool IsActive { get; set; }

        public IQueryable<OrganizationApplicationUser> OrganizationApplicationUsers { get; set; }

        public ApplicationUser():base()
        {
            IsActive = true;
            IsBlocked = false;
            DateJoined = DateTime.Now;
            DateUpdated = DateTime.Now;
        }

        public IQueryable<Organization> GetOrganizations()
        {
            return OrganizationApplicationUsers.Select(x => x.Organization);
;       }
    }
}

DbContext :

using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using Verbonding.Models;

namespace Verbonding.Data
{
    public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options)
        {
        }

        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);

            builder.Entity<OrganizationApplicationUser>().HasKey(x => new { x.OrganizationId, x.ApplicationUserId });
        }

        public DbSet<Country> Countries { get; set; }
        public DbSet<Address> Addresses { get; set; }
        public DbSet<Organization> Organizations { get; set; }
        public DbSet<Category> Categories { get; set; }
        public DbSet<Event> Events { get; set; }
        public DbSet<OrganizationApplicationUser> OrganizationApplicationUsers { get; set; }
    }
}

After some research I also added this code to the OnModelCreating method.

builder.Entity<OrganizationApplicationUser>()
    .HasOne(ou => ou.Organization)
    .WithMany(o => o.OrganizationApplicationUsers)
    .HasForeignKey(ou => ou.Organization);

builder.Entity<OrganizationApplicationUser>()
    .HasOne(ou => ou.ApplicationUser)
    .WithMany(u => u.OrganizationApplicationUsers)
    .HasForeignKey(ou => ou.ApplicationUserId);

Using the debugger I found out that OrganizationApplicationUsers remains null .

What could I do to fix this?

Answer 1

if you want to have what is called a many to many relationship between entities, you need to link the ApplicationUser to the Organization directly (under the hood, entity framework is gonna create the table between, but your class won't know about it.

Other than that, in the ApplicationUser , it should be an IColletion and not an IQueryable .