make_list() (aggregation function)

Learn how to use the make_list() function to create a dynamic JSON object array of all the values of the expressions in the group.

Creates a dynamic array of all the values of expr in the group.

Syntax

make_list(expr [, maxSize])

Parameters

NameTypeRequiredDescription
exprdynamic✔️The expression used for the aggregation calculation.
maxSizeintThe maximum number of elements returned. The default and max value is 1048576.

Returns

Returns a dynamic array of all the values of expr in the group. 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.

Examples

The examples in this section show how to use the syntax to help you get started.

One column

The following example uses the datatable, shapes, to return a list of shapes in a single column.

let shapes = datatable (name: string, sideCount: int)
[
    "triangle", 3,
    "square", 4,
    "rectangle", 4,
    "pentagon", 5,
    "hexagon", 6,
    "heptagon", 7,
    "octagon", 8,
    "nonagon", 9,
    "decagon", 10
];
shapes
| summarize mylist = make_list(name)

Output

mylist
[“triangle”,“square”,“rectangle”,“pentagon”,“hexagon”,“heptagon”,“octagon”,“nonagon”,“decagon”]

Using the ‘by’ clause

The following example uses the make_list function and the by clause to create two lists of objects grouped by whether they have an even or odd number of sides.

let shapes = datatable (name: string, sideCount: int)
[
    "triangle", 3,
    "square", 4,
    "rectangle", 4,
    "pentagon", 5,
    "hexagon", 6,
    "heptagon", 7,
    "octagon", 8,
    "nonagon", 9,
    "decagon", 10
];
shapes
| summarize mylist = make_list(name) by isEvenSideCount = sideCount % 2 == 0

Output

isEvenSideCountmylist
false[“triangle”,“pentagon”,“heptagon”,“nonagon”]
true[“square”,“rectangle”,“hexagon”,“octagon”,“decagon”]

Packing a dynamic object

The following examples show how to pack a dynamic object in a column before making it a list. It returns a column with a boolean table isEvenSideCount indicating whether the side count is even or odd and a mylist column that contains lists of packed bags int each category.

let shapes = datatable (name: string, sideCount: int)
[
    "triangle", 3,
    "square", 4,
    "rectangle", 4,
    "pentagon", 5,
    "hexagon", 6,
    "heptagon", 7,
    "octagon", 8,
    "nonagon", 9,
    "decagon", 10
];
shapes
| extend d = bag_pack("name", name, "sideCount", sideCount)
| summarize mylist = make_list(d) by isEvenSideCount = sideCount % 2 == 0

Output

isEvenSideCountmylist
false[{“name”:“triangle”,“sideCount”:3},{“name”:“pentagon”,“sideCount”:5},{“name”:“heptagon”,“sideCount”:7},{“name”:“nonagon”,“sideCount”:9}]
true[{“name”:“square”,“sideCount”:4},{“name”:“rectangle”,“sideCount”:4},{“name”:“hexagon”,“sideCount”:6},{“name”:“octagon”,“sideCount”:8},{“name”:“decagon”,“sideCount”:10}]

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