make_list_if() (aggregation function)

Learn how to use the make_list_if() aggregation function to create a dynamic JSON object of expression values where the predicate evaluates to true.

Creates a dynamic array of expr values in the group for which predicate evaluates to true.

Syntax

make_list_if(expr, predicate [, maxSize])

Parameters

NameTypeRequiredDescription
exprstring✔️The expression used for the aggregation calculation.
predicatestring✔️A predicate that has to evaluate to true in order for expr to be added to the result.
maxSizeintegerThe maximum number of elements returned. The default and max value is 1048576.

Returns

Returns a dynamic array of expr values in the group for which predicate evaluates to true. If the input to the summarize operator isn’t sorted, the order of elements in the resulting array is undefined. If the input to the summarize operator is sorted, the order of elements in the resulting array tracks that of the input.

Example

The following example shows a list of names with more than 4 letters.

let T = datatable(name:string, day_of_birth:long)
[
   "John", 9,
   "Paul", 18,
   "George", 25,
   "Ringo", 7
];
T
| summarize make_list_if(name, strlen(name) > 4)

Output

list_name
[“George”, “Ringo”]

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