linq - How do Group by a child property of a child property that may be null? -

how go grouping following?

people.groupby(p=>p.addresses.getfirstordefault().state); 

without failing on people don't have address?

• can done in 1 statement?
• if not, have first distinct() list of various addresses members? how? (actually -- if possible -- great learn how b :-) )
• i havn't seen it, there equivalent getfirstornew() can used instantiate , return non-null?

thank much!

it can done in 1 statement, yes:

// set whatever need address dummyaddress = new address { state = "" };  people.groupby(p => (p.addresses.getfirstordefault() ?? dummyaddress).state); 

alternatively, might want write helper method:

public string getstate(address address) {     return address == null ? null : address.state; } 

then can use:

people.groupby(p => getstate(p.addresses.getfirstordefault()));