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firstNonNull

Description

Return the first non-null value from a list of arguments, in the order they are provided.

Note

Works only on scalar values such as number, string, or timestamp. Does not work on objects.

Syntax

Like many functions in DataPrime, firstNonNull supports two notations, function and method. These interchangeable forms allow flexibility in how you structure expressions.

Function notation

firstNonNull(value: T, ...values: T): T

Method notation

(value: T).firstNonNull(...values: T): T

Arguments

Name	Type	Required	Description
value	T	true	The first argument to check for a non-null value
...values	T	true	Subsequent arguments to check, in order

Example

Use case: Consolidate inconsistent field names for the same logical value

Logs may contain a user identifier under different field names (userId, user_id, user_identifier). Instead of writing complex conditionals, firstNonNull returns the first populated value across these fields, creating schema-on-read consistency.

Example data

{
    "userId": "123",
    "user_id": null,
    "user_identifier": null
},
{
    "userId": null,
    "user_id": "456",
    "user_identifier": null
},
{
    "userId": null,
    "user_id": null,
    "user_identifier": "789"
}

Example query

Function notation

choose canonical_user_id from firstNonNull(userId, user_id, user_identifier)

Method notation

choose canonical_user_id from userId.firstNonNull(user_id, user_identifier)

Example output

{
    "canonical_user_id": "123"
},
{
    "canonical_user_id": "456"
},
{
    "canonical_user_id": "789"
}