i new linq , entity framework, , receiving null reference exception on query:
using (var db = new phoenixcontext()) { tblcustomer cust = (from c in db.tblcustomer c.customerid == _customerid select c).firstordefault(); string altphone; altphone = cust.tblcustomercontactinformation1.tblcustomercontactinformationphone.where(p => p.phonetypeid == 2).firstordefault().phone; ) there single row in tblcustomercontactinformationphone. clause should remove it, , should end getting empty string. however, instead receive:
object reference not set instance of object. what doing wrong, , how do correctly empty result set converted empty string?
the linked question not helpful, specific use of linq, question not cover. @evanmcdonnal's answer quite helpful, , solved problem.
this going closed because question duplicates 1000000000000 other nullreferenceexception questions have been asked before.
think .where(p => p.phonetypeid == 2).firstordefault().phone
what happens when there no item in tblcustomercontactinformationphone phonetypeid of 2? firstordefault gives 'default' in case null , thevalueretuendfromfirstordefaultwhichisnull.phone , nullreferenceexception.
instead break 2 lines.
string phone = string.empty; var temp = cust.tblcustomercontactinformation1.tblcustomercontactinformationphone.where(p => p.phonetypeid == 2).firstordefault(); if (temp != null) phone = temp.phone; edit: option use select value of phone can use null coalescing operator you're trying to. this;
var phone = cust.tblcustomercontactinformation1.tblcustomercontactinformationphone.where(p => p.phonetypeid == 2).select(x => x.phone).firstordefault() ?? string.empty; this works fine because lambda expression in select applied 0 elements if none returned end getting null firstordefault in case you'll take empty string.
