Creating a composite key in Entity Framework

Question

using System.ComponentModel.DataAnnotations;

namespace exmapleNameSpace.DTO
{
    public class Edges
    {
        public long Id { get; set; }
        [Required]
        public string NameEdge;
        [Required]
        public Item Neighbor_ID1 { get; set; }
        [Required]
        public bool ID1isFile { get; set; }
        [Required]
        public Item Neighbor_ID2 { get; set; }
        [Required]
        public bool ID2isFile { get; set; }
    }
}

Items model

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

namespace exampleNameSpace.DTO
{
    public class Item
    {
        public long Id { get; set; }
        [Required]
        [StringLength(100)]
        public string Name { get; set; }
        [Required]
        public bool isFolder { get; set; }
        [Required]
        public bool isFile { get; set; }
        [RegularExpression(@"\w.([a - z]|[A-Z])")]
        [StringLength(100)]
        public string extension { get; set; }
        [Required]
        [StringLength(100)]
        public string parentPath { get; set; }
        [Required]
        public bool isEmpty { get; set; }
    }
}

I currently have my index built keeping ID as primary key in both the entities. I have Neighbor_ID1 and Neighbor_ID2 as two foreign keys, however I want to make a composite key consisting of (Neighbor_ID1, Neighbor_ID2) for uniquely identifying edges.

Can I just add [Key] annotations for both and edit my up method to have AddForeignKeyOperations() ?

I am quite new to EF and would like to know the advantages or disadvantages of the approach.

PS: I understand that cascade delete operations with my current approach wouldn't work. Assume a connected acyclic graph topology in between the said Edges and Verteces and that I would want a many-to-many relationship ideally.

Does this answer your question? [Mapping composite keys using EF code first](https://stackoverflow.com/questions/19792295/mapping-composite-keys-using-ef-code-first) — Badro Niaimi, Dec 13 '19 at 16:41
Why should the question be closed, when the duplicate pointed to ,doesn't answer the question completely? @marc_s — AvidJoe, Dec 13 '19 at 21:35
The accepted answer clearly shows how to do this - why doesn't that answer your question?? — marc_s, Dec 14 '19 at 06:57
"I am quite new to EF and would like to know the advantages or disadvantages of the approach. PS: I understand that cascade delete operations with my current approach wouldn't work. Assume a connected acyclic graph topology in between the said Edges and Verteces and that I would want a many-to-many relationship ideally" because i wanted to know what would happen in this scenario and if it would be a good idea in the first place @marc_s — AvidJoe, Dec 14 '19 at 09:49

Creating a composite key in Entity Framework

0 Answers0