java - Zip reactive flow with itself -


i'm using java reactor core, , have reactive flux of objects. each object of flux need external query return 1 different object each input. newly generated flux needs zipped original 1 - items of 2 flux must synchronized , generated in same order.

i'm re-using same flow twice, this:

 flux<myobj> atest = flux.fromiterable(alistofobj);  flux<string> myobjlists = atest.map(o -> myrepository.findbyid(o.name)).map(o -> {   if (!o.ispresent()) {     system.out.println("fallback empty-object");     return "";   }   list<string> l = o.get();   if (l.size() > 1) {     system.out.println("that's bad");   }   return l.get(0); });  flux.zip(atest, myobjlists, (a, b) -> dosomethingwith(a,b))

is right way it? if myobjlists emits error, how prevent zip phase skip failing iteration?

i've opted using tuples , optionals (to prevent null-items break flux), don't need re-use initial flux:

flux<tuple<myobj, optional<string>>> myobjlists = flux.fromiterable(alistofobj)   .map(o -> tuples.of(o, optional.ofnullable(myrepository.findbyid(o.name))   .flatmap(t -> {     if (!t.gett2().ispresent()) {       system.out.println("discarding item");       return flux.empty();     }     list<string> l = t.gett2().get();     if (l.size() > 1) {       system.out.println("that's bad");     }     return tuples.of(t.gett1(), l.get(0));   })   .map(t -> dosomethingwith(t.gett1(),t.gett2()))

note flatmap replaced .map().filter(), removing tuples missing optional items


Comments

Post a Comment

Popular posts from this blog

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

python Tkinter Capturing keyboard events save as one single string -

is possible store keyboard events 1 string? code below stores 1 char , prints it. card reader or bar code reader, contains collection of character/ string not 1 character @ time. goal save char pressed text variable. from tkinter import * root = tk() def key(event): text= event.char text+= event.char print ("pressed", text) def callback(event): frame.focus_set() print ("clicked at", event.x, event.y) frame = frame(root, width=100, height=100) frame.bind("<key>", key) frame.bind("<button-1>", callback) frame.pack() root.mainloop() currently, creating text variable , everytime key() function gets called, , text stores last character typed. you can define text module level variable , , use module level text inside key function - text = '' def key(event): global text text+= event.char print("pressed", text)
Read more

sql server - Why does Linq-to-SQL add unnecessary COUNT()? -

here tables: create table customer ( cid int primary key, name varchar(32) ) create table ord ( oid int primary key, cid int foreign key references customer, address varchar(20) ) here's linq-to-sql statement: var aaa = c in db.customer select new { c, o = c.ord.tolist() }; and here's inexplicable query generated linq-to-sql: select [t0].[cid] [cid], [t0].[name] [name], [t1].[oid] [oid], [t1].[cid] [cid2], [t1].[address] [address], (select count(*) [dbo].[ord] [t2] [t2].[cid] = [t0].[cid]) [value] [dbo].[customer] [t0] left outer join [dbo].[ord] [t1] on [t1].[cid] = [t0].[cid] order [t0].[cid], [t1].[oid] i want understand how rid of count(*) part. it's entirely uncalled for! linq needs count(*) in order determine number of entries returned o = c.ord.tolist() .
Read more