c# - Using a Dictionary with PredicateBuilder? -

i have dictionary<string,object> of search terms , values. in case term key. example is:

var args = new dictionary<string,object>() {{"name","joe"},                                             {"occupation","salesman"}}; 

i using predicatebuilder build where clause , works, wondering if there more concise way dictionary instead of having call if(args.containskey(...) every search term in dictionary? how doing now:

list<person> persons; var predicate = predicatebuilder.false<person>();  if (args.containskey("name")) {     string name = args["name"].tostring();     predicate = predicate.or(x => x.name == name); }   if (args.containskey("name")) {     string age = args["age"].tostring();     predicate = predicate.or(x => x.age == age); }  persons = _context.persons.asexpandable().where(predicate).tolist(); 

also, if declare string name outside if block, resharper says access modified closure, matter in case? example

string name;  if (args.containskey("name")) {     name = args["name"].tostring();     predicate = predicate.or(x => x.name == name); //access modified closure } 

but in above, not modifying name anywhere, why tell me this?

i new predicatebuilder, if explain predicatebuilder.false<person>() means opposed predicatebuilder.true<person>() , compile method do?

also, if declare string name outside if block, resharper says access modified closure, matter in case?

the code still work despite fact code generates warning. happens not problem unless modify name variable time before invoke closure. in code you've shown never use again, wouldn't problem, if ever modified in code shown after code have problem.

why want in first place? starters, don't see point of variable begin with. why not write: x => x.name == args["name"]? if did want local variable this, why want scope @ higher level? should scope variable @ lowest scope possible while still allowing accessed needs be. shouldn't modifying outside if, don't expose outside if.

i new predicatebuilder, if explain predicatebuilder.false() means opposed predicatebuilder.true()

it creates expression resolves false if invoked instead of true...

note false || variable equivalent variable. reason want initialize false avoid special-casing first actual check want initializing predicatebuilder there. allows each of variables consistent , or whatever predicatebuilder resolves to.

what compile method do?

it compiles expression delegate can invoked.