Entity Framework Core not loading related data from reference table

Question

MY Model M:M relationship Reference to https://www.entityframeworktutorial.net/efcore/configure-many-to-many-relationship-in-ef-core.aspx

Models

public class Post
{
    [Key]
    public int Id { get; set; }
    [Display(Name = "Created By:")]
    public AppUser AuthorId { get; set; }
    [Required]
    public string Title { get; set; }
    public string metaTitle { get; set; }
    [Required]
    public string Body { get; set; }
    public bool Published { get; set; } 
    public bool ISFeatured { get; set; }
    public DateTime CretedDate { get; set; } = DateTime.Now;
    public DateTime ModifiyDate { get; set; } = DateTime.Now;
    public IList<Comment> Comments { get; set; }
    public IList<PostTag> PostTag { get; set; }
    public IList<PostCategory> PostCategory { get; set; }
    public IList<Images> Images { get; set; }

}

public class Tag
{
    [Key]
    public int Id { get; set; }
    [Required]
    public string Name { get; set; }
    public bool Published { get; set; } = true;
    public DateTime CretedDate { get; set; } = DateTime.Now;
    public DateTime ModifiyDate { get; set; } = DateTime.Now;
    public IList<PostTag> PostTag { get; set; }
    public IList<Images> Images { get; set; }


}

public class PostTag
{

    public int TagId { get; set; }
   
    public int PostId { get; set; }

    public Post Post { get; set; }

    public Tag Tag { get; set; }
    public AppUser AppUser { get; set; }

}

DB context

modelBuilder.Entity<Post>()
        .HasMany(c => c.Comments)
        .WithOne(e => e.Post);

modelBuilder.Entity<PostCategory>().HasKey(p => new
{
    p.PostId,p.CategoryId
});

modelBuilder.Entity<PostCategory>()
    .HasOne(p => p.post).
    WithMany(p => p.PostCategory).
    HasForeignKey(p => p.PostId);

modelBuilder.Entity<PostCategory>().
    HasOne(p => p.Category).
    WithMany(p => p.PostCategory).
    HasForeignKey(p => p.CategoryId);

On the controller, side fetching all posts, it is bringing all the posts but not getting any data from the related tables. Example Tags, Categories

Controller

public async Task<IActionResult> Index()
{
    return View(await _context.Post.ToListAsync());
}

Update Action

Tags reference is empty

EfCore uses eager loading as a default and you need to specify the loading depth using the.Include extension. https://stackoverflow.com/a/29092178/314291 — StuartLC, Jun 21 '20 at 07:32

score 2 · Answer 1 · answered Jun 21 '20 at 07:32

2

try _context.Post.Include(x => x.PostCategory) and so on.

Reference: https://learn.microsoft.com/en-us/ef/core/querying/related-data

answered Jun 21 '20 at 07:32

Vivek Nuna

25,472
25
109
197

I changed it still no data showing please check image 2 – ZCoder Jun 21 '20 at 07:40
It means `PostCategory` does not have any item – Vivek Nuna Jun 21 '20 at 07:46
but quick question can you check the next image it fetching tags id bu the reference is empty – ZCoder Jun 21 '20 at 08:14

score 2 · Accepted Answer · answered Jun 22 '20 at 06:58

2

Use ThenInclude to continue including further levels of related data.

 var posts = _context.Posts.Include(p => p.PostTag).ThenInclude(pt => pt.Tag).ToList();

answered Jun 22 '20 at 06:58

mj1313

7,930
2
12
32

Entity Framework Core not loading related data from reference table

2 Answers2