Using LINQ to query nested classes in db4o? -

run tricky problem db4o , simple nested structures.

problem: when use linq pull data out of db4o, pulling out data (i.e. "where" clause doesn't seem working).

i have nested objects:

root ----symbol (spx)                    |          |------day 1: date: 2010-10-18, string "spx meta"    |          |------day 2: date: 2010-10-19, string "spx meta"    |    |    |-----symbol (ibm)                              |------day 1: date: 2010-10-18, string "ibm meta"               |------day 2: date: 2010-10-19, string "ibm meta" 

i create 2 symbols:

  symbol sym1 = new symbol("spx");   symbol sym2 = new symbol("ibm"); 

i create trading days:

  // spx   tradingday day1 = new tradingday(new datetime(2010, 10, 18), "spx meta");   tradingday day2 = new tradingday(new datetime(2010, 10, 19), "spx meta");    // ibm   tradingday day3 = new tradingday(new datetime(2010, 10, 18), "ibm meta");   tradingday day4 = new tradingday(new datetime(2010, 10, 19), "ibm meta"); 

i assign couple of days each symbols:

  sym1.assigntradingday(day1);   sym1.assigntradingday(day2);    sym2.assigntradingday(day3);   sym2.assigntradingday(day4); 

i persist db4o object database:

  // store in database.   db4o.db.store(sym1);   db4o.db.store(sym2);   db4o.db.commit();   

pretty simple far.

i check database "db4o object manager enterprise", , sure enough, there 2 symbols, , if click on each symbol, each 1 contains 2 days.

now, linq query pull data out:

 var daysforsymbols1 = symbol s in db4o.db                        tradingday t in db4o.db                        (s.symbolglobal == "ibm"                                && t.date == new datetime(2010, 10, 19))                        select new                        {                          s.symbolglobal,                          t.date,                          t.meta                        };  foreach (var d in daysforsymbols1)  {    console.writeline("{0} - {1} - {2}", d.symbolglobal, d.date.date, d.meta);  }  

and, weird happens:

ibm - 10/19/2010 12:00:00 - spx meta     // line should not appear because have specified "ibm" in filter. ibm - 10/19/2010 12:00:00 - ibm meta 

despite fact specified should return data "spx" returning data "ibm" well.

am doing wrong?

you didn't post exact definition of classes doing cartesian product in linq query - creating every possible combination whereas want "matching" combinations (since trading day in schema reason seems associated symbol). should instead join, like:

  tradingday t in db4o.db   join symbol s in db4o.db   on s.symbolglobal equals t.symbolglobal    (s.symbolglobal == "ibm"           && t.date == new datetime(2010, 10, 19))   ...