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How to add a foreign key into a table using one-to-one relationship in ASP.NET Core 6 Web API?

I am new to ASP.NET, how can I make my item table save the categoryID which I get from the category table? As an example I want the item "Apple mobile phone" to have the category ID which refers to category name which is electronics, I hope you got the picture.
Here is model:
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace WebApplication1.Models
{
public class itemTable
{
[Key]
public int Id { get; set; }
public string company { get; set; }
public string availability { get; set; }
public decimal price { get; set; }
public decimal discount { get; set; }
public decimal tax { get; set; }
public string description { get; set; }
public int categoryid { get; set; }
}
public class categories
{
[Key]
public int categoryID { get; set; }
public string categoryName { get; set; }
}
}
And here is my DbContext:
using Microsoft.EntityFrameworkCore;
using System.Diagnostics;
using WebApplication1.Models;
namespace WebApplication1.Context
{
public class itemTableDbContext : DbContext
{
public itemTableDbContext(DbContextOptions options) : base(options)
{
}
public DbSet<itemTable> ItemTables { get; set; }
public DbSet<categories> categories { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<itemTable>().ToTable("itemtable");
modelBuilder.Entity<categories>().ToTable("categories");
}
}
}
I tried all the possible ways but there is always something wrong, multiple items might be in the same category like phone brand items are all under the "electronics" category

You can configure One-to-One relationship between two entities in such way:
public class ItemTable
{
[Key]
public int Id { get; set; }
public string Company { get; set; }
public string Availability { get; set; }
public decimal Price { get; set; }
public decimal Discount { get; set; }
public decimal Tax { get; set; }
public string Description { get; set; }
public virtual Category Category { get; set; }
}
public class Category
{
[Key]
[ForeignKey("ItemTable")]
public int CategoryID { get; set; }
public string CategoryName { get; set; }
public virtual ItemTable ItemTable { get; set; }
}
Note: Better to use PascalCase in C#

Many to Many with EF, FluentAPI and Identity

I want to add a many-to-many-relationship to my database using EF 6.
I want to add a many to many between the AppUser and Courses. Here are my models:
AppUser
using Microsoft.AspNetCore.Identity;
using System;
using System.Collections.Generic;
namespace WebApplication2.Models
{
public class AppUser : IdentityUser<Guid>
{
public string LastName { get; set; }
public string FirstMidName { get; set; }
public DateTime EnrollmentDate { get; set; }
public IList<AppUserCourse> AppUserCourses { get; set; }
public virtual ICollection<Enrollment> Enrollments { get; set; }
}
}
Course
namespace WebApplication2.Models
{
public class Course
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int CourseID { get; set; }
public string Title { get; set; }
public int Credits { get; set; }
public virtual ICollection<Enrollment> Enrollments { get; set; }
public IList<AppUserCourse> AppUserCourses { get; set; }
}
}
AppUserCourse (Joined Table)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
namespace WebApplication2.Models
{
public class AppUserCourse
{
public Guid AppUserId { get; set; }
public AppUser AppUser { get; set; }
public int CourseId { get; set; }
public Course Course { get; set; }
}
}
DataContext.cs
using WebApplication2.Models;
using Microsoft.EntityFrameworkCore;
using System;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
namespace WebApplication2
{
public class DataContext : IdentityDbContext<AppUser, AppRole, Guid>
{
public DataContext(DbContextOptions<DataContext> options) : base(options)
{
}
public DbSet<Course> Courses { get; set; }
public DbSet<Enrollment> Enrollments { get; set; }
public DbSet<AppUser> AppUsers { get; set; }
public DbSet<AppUserCourse> AppUserCourses { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Course>().ToTable("Course");
modelBuilder.Entity<Enrollment>().ToTable("Enrollment");
modelBuilder.Entity<AppUserCourse>().HasKey(i => new { i.AppUserId, i.CourseId });
}
}
}
When I know do a migration and update my database, EF is creating my something strange in the AppUserCourses-Table:
It creates my the AppUserId twice (AppUserId and AppuserId1): Former as int and latter as uniqueidentifier.
I would need it just once as unique identifier. When I now try to add a new AppUserCourse, I get the error message:
Operand type clash: uniqueidentifier is incompatible with int.

On your AppUserCourse remove the entities, so it looks like the following, re-create your migrations too
public class AppUserCourse
{
public Guid AppUserId { get; set; }
public int CourseId { get; set; }
}
That will create your many to many link
The following is an example I've set up
public class Player
{
public int Id { get; set; }
public string Firstname { get; set; }
public string Surname { get; set; }
public List<PlayerGroup> PlayerGroups { get; set; }
}
public class PlayerGroup
{
public int PlayerId { get; set; }
public int GroupId { get; set; }
}
public class Group
{
public int Id { get; set; }
public string Name { get; set; }
public List<PlayerGroup> PlayerGroups { get; set; }
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<PlayerGroup>().HasKey(x => new {x.GroupId, x.PlayerId});
}
Creates the following

Code First Migration: Two foreign keys referencing on the same table in Entity Framework Core

I have the following Models in ASP.NET(Core 1.0) MVC Framework. I am using Entity Framework Core. I want to create a table "Deliveries" with two foreign keys from the same table Addresses(a pick-up address and a drop-off address). My implementation is wrong so I would like to ask you if you know:
how to declare those properties
how to set onupdate and ondelete actions for those keys?
ApplicationDbContext.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using JBCoreApp.Models;
using Microsoft.EntityFrameworkCore.Metadata;
namespace JBCoreApp.Data
{
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
: base(options)
{
}
public DbSet<Country> Countries { get; set; }
public DbSet<AddressType> AddressTypes { get; set; }
public DbSet<Address> Addresses { get; set; }
public DbSet<Profile> Profiles { get; set; }
public DbSet<VehicleType> VehicleTypes { get; set; }
public DbSet<LicenseCategory> LicenseCategories { get; set; }
public DbSet<Driver> Drivers { get; set; }
public DbSet<DriverLicense> DriverLicenses { get; set; }
public DbSet<Priority> Priorities { get; set; }
public DbSet<Sender> Senders { get; set; }
public DbSet<Status> Statuses { get; set; }
public DbSet<Vehicle> Vehicles { get; set; }
public DbSet<Delivery> Deliveries { get; set; }
public DbSet<DeliveryStatus> DeliveryStatus { get; set; }
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
// Customize the ASP.NET Identity model and override the defaults if needed.
// For example, you can rename the ASP.NET Identity table names and more.
// Add your customizations after calling base.OnModelCreating(builder);
builder.Entity<Delivery>()
.HasOne(a => a.DropOffAddress)
.WithOne()
.HasForeignKey<Address>(a => a.Id)
.OnDelete(DeleteBehavior.Restrict);
builder.Entity<Delivery>()
.HasOne(a => a.PickUpAddress)
.WithOne()
.HasForeignKey<Address>(a=> a.Id)
.OnDelete(DeleteBehavior.Restrict);
}
}
}
Address.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace JBCoreApp.Models
{
[Table("Addresses")]
public class Address
{
public Address()
{
}
[Key]
public int Id { get; set; }
public int ProfileId { get; set; }
public Profile Profile { get; set; }
public int TypeId { get; set; }
[ForeignKey("TypeId")]
public AddressType AddressType { get; set; }
public string Street { get; set; }
public string StreetNumber { get; set; }
public string PostCode { get; set; }
public string City { get; set; }
public string CountryId { get; set; }
public Country Country { get; set; }
public string Notes { get; set; }
}
}
Delivery.cs
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Threading.Tasks;
namespace JBCoreApp.Models
{
[Table("Deliveries")]
public class Delivery
{
public Delivery()
{
}
[Key]
public int Id { get; set; }
[Required]
public int SenderId { get; set; }
public Sender Sender { get; set; }
[Required]
public int VehicleTypeId { get; set; }
public VehicleType VehicleType { get; set; }
[Required]
public int PriorityId { get; set; }
public Priority Priority { get; set; }
public int DriverId { get; set; }
public Driver Driver { get; set; }
[ForeignKey("PickUpAddressId")]
public Address PickUpAddress { get; set; }
public int PickUpAddressId { get; set; }
[ForeignKey("DropOffAddressId")]
public Address DropOffAddress { get; set; }
public int DropOffAddressId { get; set; }
public DateTime PickUpDateTime { get; set; }
public DateTime DropOffDateTime { get; set; }
public DateTime Deadline { get; set; }
public string Description { get; set; }
public string Price { get; set; }
[Timestamp]
public Byte[] TimeStamp { get; set; }
}
}

One-to-Many Relationship with ApplicationUser class

I have this User class :
public class User
{
public int UserID { get; set; }
public string UserName { get; set; }
public string Email { get; set; }
public virtual ICollection<Project> Projects { get; set; }
}
And this Project Class :
public class Project
{
public int ProjectID { get; set; }
public int UserID { get; set; }
public string ProjectTitle { get; set; }
public virtual User User { get; set; }
}
There is a one-to-many relationship between User and Project as you can see.
Instead of my User class, I want to use Identity's ApplicationUser class. So would it be ok if I change IdentityModels.cs to this :
public class ApplicationUser : IdentityUser
{
public int UserID { get; set; }
public string ProjectTitle { get; set; }
public virtual User User { get; set; }
}
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
public ApplicationDbContext()
: base("DefaultConnection")
{
}
}
And How should I change AccountViewModel.cs? should I add these
public string Email { get; set; }
public int UserID { get; set; }
to every ViewModel in that file?
Finally how should I change Project class? Should I do this :
public class Project
{
public int ProjectID { get; set; }
public int UserID { get; set; }
public string ProjectTitle { get; set; }
public virtual ApplicationUser ApplicationUser { get; set; }
}
If you can answer to my this long question, I would be very glad. Thanks.

How to ignore an inner nested object when using AutoMapper

Hello I have the classes:
Class User
public class User
{
public Int64 Id { get; set; }
public string Name { get; set; }
public string Email { get; set; }
public Profile Profile { get; set; } //EF one to one
}
Class Profile
public class Profile
{
public Int64 Id { get; set; }
public string Skype { get; set; }
public string Phone { get; set; }
public string Mobile { get; set; }
public virtual ICollection<Address> Addresses { get; set; }
public virtual User User { get; set; } //This is because EF Mappings
}
Class User DTO
public class UserDTO
{
public string Name { get; set; }
public string Email { get; set; }
public Profile Profile { get; set; }
}
I did the configurations to Map User to UserDTO
Mapper.CreateMap<User, UserDTO>();
I need to have the Profile.User because of the Entity Framework One to One Relationship but I don't want the Profile.User to be shown in the Mapping.
How can I ignore the Profile.User?

You could use a UserProfileDTO class that omits User
public class UserProfileDTO
{
public string Skype { get; set; }
public string Phone { get; set; }
public string Mobile { get; set; }
public ICollection<AddressDTO> Addresses { get; set; }
}
public class UserDTO
{
public string Name { get; set; }
public string Email { get; set; }
public UserProfileDTO Profile { get; set; }
}
Mapper.CreateMap<User, UserDTO>();
Mapper.CreateMap<Profile, UserProfileDTO>();