Entity Framework: A referential integrity constraint violation on many to many relationship

Question

Hey I have an application with a bunch of inproc caching and entity framework. When I want to write an update to an entity I reattach the cached copy. I track all things I\'

Answer 1

I just had this problem and came up with a pretty quick solution. My issue was with a many-many table.

Public class Pictures_Tag
{
    [Key]
    [Column(Order = 0)]
    [ForeignKey("Picture")]
    public Int16 Picture_ID { get; set; }
    [Key]
    [Column(Order = 1)]
    [ForeignKey("ImageTag")]
    public Int16 ImageTag_ID { get; set; }
    public virtual Picture Picture { get; set; }
    public virtual ImageTag ImageTag { get; set; }
}

I added the line where I assigned Picture = db.Pictures... and then it worked fine (not exactly sure why)

[HttpPost]
public ActionResult Edit2(WebSiteEF2017C.Models.Pictures_Tag p)
{     
    using (var db = new thisModel(Session["org"].ToString())
    {
         p.Picture = db.Pictures.Where(z => z.ID == p.Picture_ID).FirstOrDefault();
         db.Pictures_Tags.Attach(p);
         db.Entry(p).State = EntityState.Modified;
         db.SaveChanges();
         return View(db.Pictures_Tags.Include(x => x.Picture)
                    .Where(n => n.Picture_ID == p.Picture_ID & n.ImageTag_ID == p.ImageTag_ID).FirstOrDefault());
    }
}