CODEWITHSUNDEEP
c#asp.net-mvcangularjslinq
James
James

Reputation: 1392

Entity Framework, eager loading entites

I have 3 classes which I would like to 'talk' to each other on a ASP.NET MVC C# WEBAPI app. They are, Item, which can have only one User but the User can make multiple Comments on multiple Items and a Comment can have multiple Users but only one Item

My classes are as follows:

public class Item
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

    public ICollection<Comment> Comments { get; set; }
    public User User { get; set; }
}

public class User
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }

    public ICollection<Item> Items { get; set; }
    public ICollection<Comment> Comments { get; set; }
}  

public class Comment
{
    public int Id { get; set; }
    public string Message { get; set; }
    public bool Important { get; set; }

    public Item Item { get; set; }
    public User User { get; set; }
}

I'm using angularJs front end, and so that I don't get a forever repeating loop I have configured the following:

GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Serialize;
        GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;

I'm using entity framework 6 and I want to Display all items including the comments and the users who have commented

I have read and feel? that Projection using Linq is probably best?

I have the following in my dbContext. (P.S, I've disabled LazyLoading, and including the System.Data.Entity namespace)

using(var _db = new dbContext)
{
   var model = _db.Items.Include(i=>i.Comments.Select(p=>p.User).Select(vm=>new ViewModelItem(){
     //here I think is where I would say.... 
     ViewModelItem.Name = x.Name,
     ViewModelItem.Description = x.Description,
     ViewModelItem.Comments = ///
     ViewModelItem.Comments.User.Name = ///
   })).ToList();

  return Ok(model);
}

I'm not sure where to go from here.

So I want to display All the comments and include the User who owns the Item but also include All the comments for that Item, and all the Users who have commented on that Item.

Without causing an infinite loop.

If I'm not being clear, please ask me to clarify. Any help as always is greatly appreciated.

Thank you

Upvotes: 0

Views: 75

Answers (1)

JWP
JWP

Reputation: 6963

Assuming your comments data is good this should do it.

    var model = db.Comment.Select(p=>
    new ViewModelItem { 
        Name =   p.User.Name,
        Comments=p,
        Description=p.Item.Description,
    });

Upvotes: 1

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