Debugging Functions Reference

Debugging Functions

Name	Description
`EXISTS`	Returns `TRUE` if the value is not an absent value
`IS_ABSENT`	Returns `TRUE` if the value is an absent value
`IF_ABSENT`	Replaces the value with an expression if it is absent
`IS_ERROR`	Catches and checks if an error has been thrown by the underlying expression
`IF_ERROR`	Replaces the value with an expression if it has thrown an error

EXISTS

Syntax:

exists(value: ANY) -> BOOLEAN

Description:

Returns TRUE if value is not the absent value.

Examples:

`value`	`exists(value)`
0L	`TRUE`
"foo"	`TRUE`
`NULL`	`TRUE`
`ABSENT`	`FALSE`

Node.js

const result = await db.pipeline()
  .collection("books")
  .select(field("rating").exists().as("hasRating"))
  .execute();test.firestore.js

Web

Example:

const result = await execute(db.pipeline()
  .collection("books")
  .select(field("rating").exists().as("hasRating"))
);test.firestore.js

Swift

let result = try await db.pipeline()
  .collection("books")
  .select([Field("rating").exists().as("hasRating")])
  .execute()PipelineSnippets.swift

Kotlin
Android

Example:

val result = db.pipeline()
    .collection("books")
    .select(field("rating").exists().alias("hasRating"))
    .execute()DocSnippets.kt

Java
Android

Example:

Task<Pipeline.Snapshot> result = db.pipeline()
    .collection("books")
    .select(field("rating").exists().alias("hasRating"))
    .execute();DocSnippets.java

Python

from google.cloud.firestore_v1.pipeline_expressions import Field

result = (
    client.pipeline()
    .collection("books")
    .select(Field.of("rating").exists().as_("hasRating"))
    .execute()
)firestore_pipelines.py

Java

Pipeline.Snapshot result =
    firestore
        .pipeline()
        .collection("books")
        .select(exists(field("rating")).as("hasRating"))
        .execute()
        .get();PipelineSnippets.java

IS_ABSENT

Syntax:

is_absent(value: ANY) -> BOOLEAN

Description:

Returns TRUE if value is the absent value, and FALSE otherwise. Absent values are values that are missing from the input, such as a missing document field.

Examples:

`value`	`is_absent(value)`
0L	`FALSE`
"foo"	`FALSE`
`NULL`	`FALSE`
`ABSENT`	`TRUE`

IF_ABSENT

Syntax:

if_absent(value: ANY, replacement: ANY) -> ANY

Description:

If value is an absent value, evaluates and returns replacement. Otherwise returns value.

Examples:

`value`	`replacement`	`if_absent(value, replacement)`
5L	0L	5L
`NULL`	0L	`NULL`
`ABSENT`	0L	0L

IS_ERROR

Syntax:

is_error(try: ANY) -> BOOLEAN

Description:

Returns TRUE if an error is thrown during the evaluation of try. Returns FALSE otherwise.

IF_ERROR

Syntax:

if_error(try: ANY, catch: ANY) -> ANY

Description:

If an error is thrown during the evaluation of try, evaluates and returns replacement. Otherwise returns the resolved value of try.

What's next

See the Pipeline Queries overview

Debugging Functions Reference