Map many to many objects using Entity Framework

Question

For example we have profile and organisation. Both have articles.

    public class Article
    {
        public int Id { get; set; }
        public string Title { get; set; }
    }

    public class Profile
    {
        public int Id { get; set; }
        public string Email { get; set; }
        public virtual ICollection<Article> Articles { get; set; }
    }

    public class Organisation
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public virtual ICollection<Article> Articles { get; set; }
    }

In this way Article should have two kinds of parent so it should have something like parent type to be able to access a parent when you select articles directly.

    public class Article
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public int ParentId { get; set; }
        public ArticleParentType Parent { get; set; }
    }

Is it possible to map it using Entity Framework?
Is it a good idea to do it?
What is the best practice for storing this kind of data?

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

public class Article
{
    public int Id { get; set; }
    public string Title { get; set; }
    public int ParentId { get; set; }
    public ArticleParentType Parent { get; set; }
}

Is it possible to map it using Entity Framework?
Is it a good idea to do it?

Possible yes but not a good idea. The underlying Database can't use a foreign key for Parentid. It would be slow.

What is the best practice for storing this kind of data?

A simple approach, with 2 Nullable parents and without CascadeOnDelete:

public class Article
{
    public int Id { get; set; }
    public string Title { get; set; }

    public virtual Profile Profile { get; set; }
    public virtual Organisation Organisation { get; set; }
}

Alternatively you could use inheritance for Article, ie class OrganisationArticle : Article {}

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Nov 1, 2015 at 8:55

Henk Holterman

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2 Comments

Alex Over a year ago

For example I decided to use "A simple approach, with 2 Nullable parents".. but there are many other questions. For example there is a post -> comments structure. Comment has two creators - User and Organisation. Should I add .Include() to each creator when I select posts from DB? What to do if you have 10 parents?

Alex Over a year ago

How exactly to refactor the class model?

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