CODEWITHSUNDEEP
c#asp.net-coremappingef-core-2.0
Fatemeh Montazeri
Fatemeh Montazeri

Reputation: 31

How can i configure one-to-many relationship in .Net Core

I want to configure a one-to-many relationship in Ef core. As you see I have a class for order and the other one for OrderItems. I do it when I use NHibernate.of course, I consider orderItem class as ValueObject.But I want to do it using EF Core.

public class Order 
{
    public long Id { get; set; }
    public long CustomerId { get; set; }
    public DateTime OrderDateTime { get; set; }

    public ICollection<OrderItem> OrderItems { get; set; }
}

public class OrderItem  
{
    public string BookId { get; set; }
    public int Quantity { get; set; }
    public decimal UnitPrice { get; set; }
    public decimal? Discount { get; set; }
    public decimal Total { get; set; }

    public Order Order { get; set; }

}

Upvotes: 0

Views: 438

Answers (3)

Mohammad
Mohammad

Reputation: 971

you should define meta data [ForeignKey] with type of primary key in order entity. after that ef core automatically set in db by your chosen name

public class Order 
{
    public long Id { get; set; }
    public long CustomerId { get; set; }
    public DateTime OrderDateTime { get; set; }

    public virtual ICollection<OrderItem> OrderItems { get; set; }
}

public class OrderItem 
{
    public long Id { get; set; }    

    [ForeignKey(nameof(OrderId)]
    public virtual Order Order { get; set; }
    public long OrderId { get; set; }

    public int Quantity { get; set; }
    public decimal UnitPrice { get; set; }
    public decimal? Discount { get; set; }
    public decimal Total { get; set; }
}

Upvotes: 3

Ashutosh Kushawaha
Ashutosh Kushawaha

Reputation: 791

Model

 public class Order     {
            public long Id { get; set; }
            public long CustomerId { get; set; }
            public DateTime OrderDateTime { get; set; }
            public virtual ICollection<OrderItem> OrderItems { get; set; }
      }

public class OrderItem

{  
    [Key]
    public int OrderItemId { get; set; }
    public string BookId { get; set; }
    public int Quantity { get; set; }
    public decimal UnitPrice { get; set; }
    public decimal? Discount { get; set; }
    public decimal Total { get; set; }
    public long OrderId{get;set;} // ForeignKey OrderId
    [ForeignKey("OrderId")]
    public virtual Order Order { get; set; }

}

// open PackageManager console

PM>add-migration "orderItem changed"
PM>update-database

Upvotes: 1

Rena
Rena

Reputation: 36715

Here is a simple demo like below:

1.Model:

public class Order
{
    public long Id { get; set; }
    public long CustomerId { get; set; }
    public DateTime OrderDateTime { get; set; }

    public ICollection<OrderItem> OrderItems { get; set; }
}

public class OrderItem
{
    public int OrderItemId { get; set; }//you need to define a primary key for OrderItem model
    public string BookId { get; set; }
    public int Quantity { get; set; }
    public decimal UnitPrice { get; set; }
    public decimal? Discount { get; set; }
    public decimal Total { get; set; }

    public Order Order { get; set; }

}

2.DbContext:

public class MyDbContext : DbContext
{
    public MyDbContext(DbContextOptions<MyDbContext> options)
        : base(options)
    {
    }

    public DbSet<Order> Orders { get; set; }
    public DbSet<OrderItem> OrderItems { get; set; }
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Order>()
                    .HasMany(c => c.OrderItems)
                    .WithOne(e => e.Order);
    }
}

3.Startup.cs:

services.AddDbContext<MyDbContext>(options =>
                options.UseSqlServer(Configuration.GetConnectionString("MyDbContext")));

4.appsettings.json:

"ConnectionStrings": {
   "MyDbContext": "Server=(localdb)\\mssqllocaldb;Database=DatabaseName;Trusted_Connection=True;MultipleActiveResultSets=true" 
}

5.Run command line on Package Nuget Manager:

PM>add-migration init
PM>update-database

Upvotes: 1

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