How to implement query function?

Question

1.table1:

([ID:`1`2`3]Name:`A`B`C;Client:`P`Q`S;ClientType:`QW`DS`WW;NameType:`jj`ll`oo;Basket:`QD`IO`LK;Sepal:5.1 4.5 23.5;Length:2 34 6;Species:`setosa`setosa`setosa)

2.write a simple function to select table1 data

api:{[Params]
   if [Params~();Params:()!()];
   defaultCols:`ID`Name`Client!(`ID`Name`Client);
if[`extraCols in key Params;
 defaultCols:defaultCols,Params[`extraCols]!Params `extraCols];
: ?[ select  from table1;();0b;defaultCols];
}

3.test api[(enlist[`extraCols]!enlist(`Species`Length))]

 ID Name  Client    Species  Length
 1    A     B        setosa    2
 2    B     Q        setosa    34
 3    C     S        setosa    6

When I used one Params to test:api[(enlist[`extraCols]!enlist(`Species))] But result type error.In my limited experience with this . Could you please help me understand this . thanks.

And i want to get below result and how to change my api

ID Name  Client    Species
1    A     B       setosa
2    B     Q       setosa
3    C     S       setosa

Please format code, description properly. Also the image is missing — NitinSingh
– NitinSingh, Commented May 25, 2018 at 5:28

Jonathon McMurray · Accepted Answer · 2018-05-25 14:02:16Z

1

I imagine the type error is coming from the statement in your if condition:

if[`extraCols in key Params;
 defaultCols:defaultCols,Params[`extraCols]!Params `extraCols]

You create a dictionary Params[`extraCols]!Params `extraCols

If there is only one element in Params`extraCols then you would need to enlist this when creating the dictionary to avoid such a type error, i.e:

enlist[Params`extraCols]!enlist Params`extraCols

It is also worthwhile putting a breakpoint inside your function to check the type of your arguments and give yourself an opportunity to debug. You should then be able to see that Params`extraCols is the atom `Species (should have type -11h) rather than a list.

edited May 25, 2018 at 14:02

Jonathon McMurray

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answered May 25, 2018 at 6:27

Jemma Borland

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2 Comments

James Over a year ago

Use api[(enlist[Species]!enlistSpecies)] still return defaultCols and no `Species col showing

Jemma Borland Over a year ago

You should update your api function as I have mentioned above, and call it with the same argument as before (api[(enlist[`extraCols]!enlist(`Species))]).

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