Entity Framework Core Mapping Multiple objects to an object in one to many

Question

I am trying to work out the best way to handle a Note object that is linked to multiple objects i.e. Contacts, Quotes. These objects can have many Notes, A Quote has many Notes.

public class Note
{
    public int Id { get; set; }
    public string Title { get; set; }        
    public string NoteDetails { get; set; }
    public DateTime CreatedDate { get; set; }

    public int? ContactId { get; set; }
    public int? QuoteId { get; set; }

    public Contact NoteContact { get; set; }
    public Quote NoteQuote { get; set; }
}

public class Contact
{
    public int Id { get; set; }
    public string Name { get; set; }        
    public string Address { get; set; }

    public ICollection<Note> Notes { get; set; }
}

public class Quote    {
    public int Id { get; set; }
    public string Title { get; set; }        
    public string Description { get; set; }

    public ICollection<Note> Notes { get; set; }
}

Is it just a case of adding foreign keys in the Notes to Contacts, Quotes etc.? Then virtual collections of Notes in the Contact, Quotes and Invoices object?

I hope I make sense in what I am trying to achieve.

Thanks

score 0 · Answer 1 · answered Mar 22 '18 at 06:48

Having a model like this (maybe is not exactly thw way you want, but you get the point):

public class Note
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string NoteDetails { get; set; }
    public DateTime CreatedDate { get; set; }


    public Quote Quote { get; set; }
    public Contact Contact { get; set; }
}

public class Contact
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Address { get; set; }

    public ICollection<Note> Notes { get; set; }
}

public class Quote
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }

    public ICollection<Note> Notes { get; set; }
}

Will create this migration:

migrationBuilder.CreateTable(
    name: "Contacts",
    columns: table => new
    {
        Id = table.Column<int>(nullable: false)
            .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
        Address = table.Column<string>(nullable: true),
        Name = table.Column<string>(nullable: true)
    },
    constraints: table =>
    {
        table.PrimaryKey("PK_Contacts", x => x.Id);
    });

migrationBuilder.CreateTable(
    name: "Quotes",
    columns: table => new
    {
        Id = table.Column<int>(nullable: false)
            .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
        Description = table.Column<string>(nullable: true),
        Title = table.Column<string>(nullable: true)
    },
    constraints: table =>
    {
        table.PrimaryKey("PK_Quotes", x => x.Id);
    });

migrationBuilder.CreateTable(
    name: "Notes",
    columns: table => new
    {
        Id = table.Column<int>(nullable: false)
            .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
        ContactId = table.Column<int>(nullable: true),
        CreatedDate = table.Column<DateTime>(nullable: false),
        NoteDetails = table.Column<string>(nullable: true),
        QuoteId = table.Column<int>(nullable: true),
        Title = table.Column<string>(nullable: true)
    },
    constraints: table =>
    {
        table.PrimaryKey("PK_Notes", x => x.Id);
        table.ForeignKey(
            name: "FK_Notes_Contacts_ContactId",
            column: x => x.ContactId,
            principalTable: "Contacts",
            principalColumn: "Id",
            onDelete: ReferentialAction.Restrict);
        table.ForeignKey(
            name: "FK_Notes_Quotes_QuoteId",
            column: x => x.QuoteId,
            principalTable: "Quotes",
            principalColumn: "Id",
            onDelete: ReferentialAction.Restrict);
    });

And finnaly, doing something like this:

var quotes = _db.Quotes.Include(q => q.Notes).ThenInclude(n => n.Contact).ToList();

you should have a list of Quotes with inner objects (Notes and Contacts) in it, and you can use the navigation properties.

Entity Framework Core Mapping Multiple objects to an object in one to many

1 Answers1