Debugging functions

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

Example:

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

Java

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.