Kql for loop to append new column

Question

I have a function which takes array input. I want to execute the function logic for each item in the array and combine each output in single dynamic output column. I'm able to achieve it for single input. Is it possible to do for multiple inputs ?

let T = datatable(a:string, b:dynamic)
[
    "hello", dynamic({"A":1,"B":2,"value1":3}),
    "world", dynamic({"value1":4,"value2":5}),
];

let F = (T:(b:dynamic), input: dynamic) {
    **//for each item in input. Combine b.value1 and return dynamic new column** 
    T | project b.value1
};
let input= dynamic(["input1", "input2"]);

// for each row in the table, function F is invoked
T | invoke F(input)

final view looks like

a                                   b                          new_ouput_column
hello                  {"A": 1,"B": 2,"value1": 3}       {"input1": 3,"input2": 3}
world                  {"value1": 4,"value2": 5  }       {"input1": 4,"input2": 4}

Balaji · Accepted Answer · 2025-03-12 03:46:18Z

0

Is it possible to do for multiple inputs ?

Yes, it is possible with multiple inputs. Try by using mv-apply key = input iterates over each value in input and tostring(key) ensures each input key is treated as a string. In below code pack(tostring(key), b.value1) is used, which creates { "input1": b.value1, "input2": b.value1 } dynamically. Now make_bag() aggregates the results into a single dynamic object per row.

let T = datatable(a:string, b:dynamic)
[
    "hello", dynamic({"A":1,"B":2,"value1":3}),
    "world", dynamic({"value1":4,"value2":5})
];

let input = dynamic(["input1", "input2"]);

T
| mv-apply key = input on 
(
    summarize new_output_column = make_bag(pack(tostring(key), b.value1))
)

Output: enter image description here

answered Mar 12 at 3:46

Balaji

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