CODEWITHSUNDEEP
kdb+
Rishabh Jain
Rishabh Jain

Reputation: 644

qPython Functional Queries

We are trying to build functional queries using qPython. Strating with simple examples to build where conditions at the run time. we defined a q function on out KDB server like

fn:{[c]
    t: (select from tbl);
    :?[t;c;0b;()];
}

in Python we open a connection and send the condition 

c = [['=', numpy.string_('TradeId'), 123456]]
result = conn.sendSync('fn', c)

when I do this, in q console I see that = operator as "=". the question is how to pass operators

Upvotes: 0

Views: 525

Answers (2)

Rishabh Jain
Rishabh Jain

Reputation: 644

@terrylynch answer works for specifically qPython

from python sending works

 c = [[ qtype.QLambda( '{x in  y}'), numpy.string_('TradeId'), [123, 456,789]]]

Upvotes: 1

terrylynch
terrylynch

Reputation: 13657

You could value the string/char on the kdb side to convert it from a string/char to the underlying kdb operator. This works in your example but you might need some extra work/testing to generalise it to all possible operators that you might send:

q)tbl:([]TradeId:0 123456 123456 123456;col2:1 2 3 4)
q)fn:{[c] c:.[c;(::;0);value];t:(select from tbl); :?[t;c;0b;()];}

q)0(`fn;enlist("=";`TradeId;123456))
TradeId col2
------------
123456  2
123456  3
123456  4

q)0(`fn;(("=";`TradeId;123456);("in";`col2;2 4)))
TradeId col2
------------
123456  2
123456  4

Note - Im using 0() to send requests within kdb itself but this should be the equivalent of sending from qPython. The bit you need to change is the c:.[c;(::;0);value]; in your kdb function

Upvotes: 0

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