c# - Listing a field from all the entities in a collection -

i'm writing out aggregated list of statuses. works fine except situation there none. @ moment, null rendered , position empty.

item.stuff.where(e => condition(e))   .select(f => f.status)   .aggregate("---", (a, b) => (a == "---") ? b : (a + b)); 

i've got a suggestion solution , improvement follows.

[flags] enum status {     none = 0,     active = 1,     inactive = 2,     pending = 4,     deleted = 8 }  item.stuff.where(e => condition(e))   .aggregate(status.none, (a, b) => | b.status) 

as i'm great fan of simpler syntax, love skipping select part. however, result not elements listed. in fact, single 1 listed (instead of 5 previously) , none appears there single status before.

perhaps i'm brain-stuck can't see why. and, consequently, not should it, neither... :(

if statuses coming extenal system (i.e. database) might need renumber statuses there well.

note works if use power-of-two values values of statuses.

eg. if use

[flags] enum status {     none = 0,     active = 1,     inactive = 2,     pending = 3,     deleted = 4 } 

then status.active | status.inactive return status.pending (1+2=3).

also, way list of distinct used statuses, i.e. if have 10 active , 5 pending items, you'll active, pending result, without frequency information.

if need information too, suggest doing grouping, like:

string.join(", ", item.stuff.where(e => condition(e))   .select(f => f.status)   .groupby(status => status)   .select(group => string.format("{0} {1}", group.count(), group.key)); 

this result in "10 active, 5 pending" or empty string if there no groups.

---

edit: think of it, string.join might better solution original question (ienumerable.aggregate great method, might overkill). like:

string.join(", ", item.stuff.where(e => condition(e)).select(f => f.status))