neo4j Multiple optional paths - cypher -

-

i'm tracking if user has liked , or voted on object in list of objects others posted.. can either likes , votes, not both. (a person can both , vote on object , these options not mutually exclusive).

to problem let me describe in relational terms (left joins used - object returned, liker , voter data returned if record of type exists)

[object]+ -> liker         + -> voter

what i'd return is:

objectid likerid  voterid 2343     null     88 2345     11       null 2382     44       1256 2400     null     null

yet every way i've sliced cannot come out . either row 2400 skipped (i've tried every combination of where), or values shifted likerid voterid column (bug?).

here sample of cypher:

    start objects=node(158)  match contestant-[:posted]->object_node-[:posted_object]->objects<-[?:posted_object]-object_node_a<-[?:likes]-liker     , objects<-[?:posted_object]-object_node_b<-[?:votes]-voter     return id(object, id(liker), id(voter)

it doesn't work if try id(object_node_a) = id(object_node_b)...

if try liker works.. same voter.. when try both.. bombs..

i've tried using , etc never full list of objects - either trims down list based upon matches, or gives me cartesian product distinct not resolve.

sql example: left join

i'm sql guy let me explain way - have objects table on left, , want left join liker table , voter table, , return both liker id , voter id on single row along object data. object records returned regardless if there voter or liker record.

[object]+ -> liker         + -> voter

is possible?

is possible via cypher?

hopefully haven't misunderstood. get

objectid likerid  voterid 2343     null     88 2345     11       null 2382     44       1256 2400     null     null

i.e. objects , id of liked , voted it, query should it-

start o=<lookup objects> match ul-[like?:liked]->o, uv-[vote?:voted]->o  return o,id(ul),id(uv)

this return objects no votes , likes, both votes , likes , either one. note if have multiple users voting same object likely, object row repeat each user. might want like

start o=<lookup objects> match ul-[like?:liked]->o, uv-[vote?:voted]->o  return o,collect(id(ul)),collect(id(uv))

to still row per object collection of user ids votes , likes.

to include person posted object well:

start o=node(4,5,6,7)  match ul-[like?:liked]->o, uv-[vote?:voted]->o, c-[:posted_object]->o  return o,id(ul),id(uv),id(c)

i created tiny sample play with: http://console.neo4j.org/r/in8g4w


Comments

Post a Comment

Popular posts from this blog

java - Jmockit String final length method mocking Issue -

-
using jmockit 1.2 jar, trying mock string's length method getting unexpected invocation exception: failed: test java.lang.illegalstateexception: missing invocation mocked type @ point; please make sure such invocations appear after declaration of suitable mock field or parameter @ stringdemo.testa$1.<init>(testa.java:17) @ stringdemo.testa.test(testa.java:13) i using testng: @test public void test() throws exception { new expectations() { @mocked("length") string astring; { astring.length(); result = 2; } }; system.out.println(a.showa("test")); } } actual class a: public class { public static int showa(string str){ int a= str.length(); return a; } } this wrong way of recording expected results. shouldn't mock , record string's length() method, record showa() instead. here solution @suppresswarnings("unused&qu
Read more

asp.net - Razor Page Hosted on IIS 6 Fails Every Morning -

-
i have simple page in intranet uses razor/asp fetch single record table , display it, plus few graphic, dashboard display. meaning, no user intervention other first time open ie internal url. the problem having every morning ie displays "page not found or network error" message. refresh page, , it's stuck , doesn't display anything. try different pc, open ie internal url , it's stuck... ...until following: login server hosting page run inetmgr go web sites, etc right click on page that's giving me problem , select browse at moment, error message: server error in '/' application. -------------------------------------------------------------------------------- type of page not served. description: type of page have requested not served because has been explicitly forbidden. extension '.cshtml' may incorrect. please review url below , make sure spelled correctly. requested url: /application/dashboard.cshtml ---------------
Read more

c++ - wxwidget compiling on windows command prompt -

-
can please guide me on method,as how compile wxwidget using windows command prompt or msys. [i can't seem find on wxwiki/wxwidget official book/anywhere else] i have compiled wxwidget instructions have provided (using msys). from searching on internet seems 1 can (maybe?) through use of makefile (is correct?) if yes: directory & how should link wx libraries in makefile if no: way besides makefile? i know can use ide's code::block , make life simpler prefer compile using command prompt/msys. thanks in advance.
Read more