Entity Framework delete child object

I have two tables without any cascade deleting. I want to开发者_运维问答 delete parent object with all child objects. I do it this way

//get parent object
return _dataContext.Menu.Include("ChildMenu").Include("ParentMenu").Include("Pictures").FirstOrDefault(m => m.MenuId == id);
//then i loop all child objects
var picList = (List<Picture>)menu.Pictures.ToList();

for (int i = 0; i < picList.Count; i++)
 {
  if (File.Exists(HttpContext.Current.Server.MapPath(picList[i].ImgPath)))
  {
     File.Delete(HttpContext.Current.Server.MapPath(picList[i].ImgPath));
  }
  if (File.Exists(HttpContext.Current.Server.MapPath(picList[i].ThumbPath)))
  {
     File.Delete(HttpContext.Current.Server.MapPath(picList[i].ThumbPath));
  }

  //**what must i do here?**
  //menu.Pictures.Remove(picList[i]);
  //                DataManager dm = new DataManager();
  //                dm.Picture.Delete(picList[i].Id);

  //menu.Pictures.de
  //_dataContext.SaveChanges();
  //picList[i] = null;

}

//delete parent object
_dataContext.DeleteObject(_dataContext.Menu.Include("ChildMenu").Include("ParentMenu")
    .Include("Pictures").FirstOrDefault(m => m.MenuId == id););
_dataContext.SaveChanges();

It is enough to set the

<OnDelete Action="Cascade" />

My situation was slightly different, and it took a while to get it right so I thought it worth documenting. I have two related tables, Quote and QuoteExtension:

• Quote (Parent, Primary Key QuoteId)
• QuoteExtension (Calculated fields for Quote, Primary and Foreign Key QuoteId)

I didn't have to set the OnDelete action to get it to work - but Craig's comment (if I could vote that up more I would!) led me to discover the issue. I was attempting to delete the Quote when QuoteExtension was not loaded. Therefore I found two ways that worked:

var quote = ent.Quote.Include("QuoteExtension").First(q => q.QuoteId == 2311);
ent.DeleteObject(quote);
ent.SaveChanges();

Or:

var quote = ent.Quote.First(q => q.QuoteId == 2311);
if (quote.QuoteExtension != null)
    ent.Refresh(RefreshMode.ClientWins, quote.QuoteExtension);
ent.DeleteObject(quote);
ent.SaveChanges();

Interestingly trying to delete QuoteExtension manually didn't work (although it may have if I had included ent.SaveChanges() in the middle - this tends to happen only at the end of a unit of work in this system so I wanted something that didn't rely on this.