c# - NullReferenceException with Auto-Generated Tables -

i have problem exception nullreferenceexception ... class auto generated ef , contains list of icollection , list supposed initialized in constructor when trying add items list shows exception.

internal partial class customer : person {      partial void objectpropertychanged(string propertyname);      public customer()     {         this.accounts = new hashset<account>();         this.customerupdates = new hashset<customerupdate>();     }      public virtual icollection<account> accounts { get; set; }     public virtual icollection<customerupdate> customerupdates { get; set; } } 

the exception thrown when trying add item collection. "this.accounts.add()"

internal partial class customer : person, icustomer {     internal customer(guid userid, string firstname, string surname)         : base(userid, firstname, surname) {  }      //list of customer accounts     ienumerable<iaccount> icustomer.accounts     {         { return accounts.asenumerable<iaccount>(); }     }      //open savingsaccount     public account opensavingsaccount(decimal amount)     {         var account = new accountsavings();         account.debit(amount, "-- opening balance --");         this.accounts.add(account);         return account;                }      //open loanaccount     public account openloanaccount(decimal amount)     {         var account = new accountloan(amount);         account.debit(amount, "-- opening balance --");         this.accounts.add(account);         return account;     } 

entity framework initializes collections if use .include(o => o.accounts) in query.

if not have include have initialize list yourself:

if (this.accounts == null)     this.accounts = new list<account>(); this.accounts.add(account);