AsNoTracking throwing error Method 'System.Data.Entity.Infrastructure.DbQuery declared on type For DbSet with collection inside

Question

I have an object

public partial class FileAttachment
{
  public FileAttachment()
  {
      this.Tags = new HashSet<Tag>();
  }
  public virtual ICollection<Tag> Tags {get; set;}
  ...other propertties
}

My context class is having

public virtual DbSet<FileAttachment> FileAtttachments {get; set;}
public virtual DbSet<Tag> Tags {get; set;} 
public virtual DbSet<Item> Items {get; set;}
   ...

I am using it in my controller like

MyContext.Items.AsNoTracking().Where(i => i.ItemId == inputId && 
           MyContext.FileAttachments.AsNoTracking.Where(f => f.RecordId == i.ReferenceId && f.RecordType == 'item').Any()).Any();

The error I am getting is

'Method 'System.Data.Entity.Infrastructure.DbQuery1[Demo.FileAttachment] AsNoTracking()' declared on type 'System.Data.Entity.Infrastructure.DbQuery1[Demo.FileAttachment]' cannot be called with instance of type 'System.Data.Entity.Core.Objects.ObjectQuery`1[Demo.FileAttachment]''

I am new to AsNoTracking(). Anyone can tell where I am doing wrong?

Answer 1

It looks like the actual requirement is to check whether an Item with a specific ID has a related FileAttachment of a specific type. There's no need for AsNoTracking() for this since the query returns a single boolean, not objects that need tracking.

If the classes had proper navigation properties, the query would be a simple:

var found= MyContext.FileAttachments.Any(f=>f.RecordType == 'item' 
                                         && f.Item.Id = ThatItemID);

Without them, the LINQ query will have to JOIN the two "unrelated" entities:

var query = from item in MyContext.Items
            join person in MyContext.FileAttachmentes
                on file.RecordId equals item.ReferenceId 
            where item.ItemID == ThatId && 
                  file.RecordType == 'item'
            select 1;
var found=query.Any();

The lack of navigation properties is a very strong sign that the model is wrong though.

A DbContext isn't a model of the database and doesn't have to mirror it. There's no need to have a single DbContext for the entire application either. Even if there are no Foreign Key Constraints between Items and FileAttachments it's possible to add relations between the classes