c# - MVC 4 and lazy loading: "Collection was modified" error when deleting multiple records -

in asp.net mvc 4 project, have model leaguemember:

public class leaguemember {     [key, column(order = 0)]     public int memberid { get; set; }      [key, column(order = 1)]     public int leagueid { get; set; }      public bool? isactive { get; set; }      public virtual league league { get; set; }      public virtual member member { get; set; }  } 

in league model, have:

public virtual icollection<leaguemember> leaguemembers { get; set; } 

in edit view of league controller, have dropdown leaguemembers , in edit action trying delete existing leaguemembers , creating new ones:

[httppost] public actionresult edit(leaguemembersviewmodel leaguememberviewmodel) {     if (modelstate.isvalid)     {         var league = leaguememberviewmodel.league;         context.entry(league).state = entitystate.modified;          /* without line next foreach statement complain             league.leaguemembers null due lazy loading..*/         context.entry(league).collection("leaguemembers").load();          var leaguemembers = leaguememberviewmodel.league.leaguemembers;          foreach (var leaguemember in leaguemembers)         {             context.leaguemembers.remove(leaguemember);         }          foreach (var memberid in leaguememberviewmodel.selectedmembers)         {             var leaguemember = new leaguemember { memberid = memberid, league = league };             context.leaguemembers.add(leaguemember);         }         context.savechanges();          return redirecttoaction("index");    }      leaguememberviewmodel.memberlist = new multiselectlist(context.members, "id", "name", leaguememberviewmodel.selectedmembers);     return view(leaguememberviewmodel); } 

when executed, line foreach (var leaguemember in leaguemembers) complains on second iteration of forloop:

collection modified; enumeration operation may not execute

is there better way delete bulk records in one-to-many relationship?

in case, to remove leaguememberviewmodel.league.leaguemembers perhaps without iterating through collection?

something like, replacing:

context.entry(league).collection("leaguemembers").load();  var leaguemembers = leaguememberviewmodel.league.leaguemembers; foreach (var leaguemember in leaguemembers) {     context.leaguemembers.remove(leaguemember); } 

with:

 leaguemember.league.leaguemembers.remove(); 

i think code has typos. example, looks var league = leaguemember.league should var league = leaguememberviewmodel.league. reading between lines suspect leaguemembers same leaguemembers of attached league object. (that attach setting entitystate.modified).

if so, error explained fact loop through loaded collection , @ same time remove items it. remedy simple:

foreach (var leaguemember in leaguemembers.toarray()) // <= toarray 

which copies collection local array not change.

as second question: no there no built-in way bulk deletes in entity framework.