any_value

Description

Returns any non-null value from the specified expression within a group. If no expression is provided, it defaults to the $d object.

Returns null if all values in the group are null.

Syntax

any_value(expression: any?): any

Arguments

Example

Use case: Select any non-null username from a group of documents

Suppose you want to group documents by team and retrieve any available username.

Example data

{
    "userId": 1,
    "team": "A Team",
    "username": null
},
{
    "userId": 2,
    "team": "A Team",
    "username": "Ryan"
},
{
    "userId": 3,
    "team": "A Team",
    "username": "Anastasia"
}

Example query

groupby team aggregate any_value(username) as random_username

Example output

The output may vary depending on the order in which documents are processed:

{
"team": "A Team",
"random_username": "Ryan"
}