FQL v4 will be decommissioned on June 30, 2025. Ensure that you complete your migration from FQL v4 to FQL v10 by that date.

Fauna accounts created after August 21, 2024 must use FQL v10. These accounts will not be able to run FQL v4 queries or access the v4 Dashboard.

For more details, see the v4 EOL announcement and migration guide. Contact support@fauna.com with any questions.

`Singleton`

This reference topic applies to FQL v4. Go to this page for the latest FQL v10 reference topics.

Singleton( ref )

singleton( ref )

Singleton( ref )

Singleton( ref )

Singleton( ref )

Singleton( ref )

Description

The Singleton function produces a set containing the Reference that you provide.

In most cases, functions cast References into sets when necessary. The only case where Singleton is required is to return a set’s events rather than a Reference’s events.

Parameters

Parameter Type Definition and Requirements

Parameter	Type	Definition and Requirements
`ref`	Reference	A reference to a resource, such as a document, collection, database, etc.

ref

Reference

A reference to a resource, such as a document, collection, database, etc.

Returns

A new Set Reference for the set which contains the single ref.

Examples

The following query creates a single-item set from the provided ref:

client.query(
  q.Singleton(q.Ref(q.Collection('posts'), '233286601218720256'))
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))

Singleton(Ref(Collection("posts"), "233286601218720256"))

result = client.query(
  q.singleton(q.ref(q.collection("posts"), "233286601218720256"))
)
print(result)

SetRef({'singleton': Ref(id=233286601218720256, collection=Ref(id=posts, collection=Ref(id=collections)))})

result, err := client.Query(
	f.Singleton(f.Ref(f.Collection("posts"), "233555580689580553")))

if err != nil {
	fmt.Fprintln(os.Stderr, err)
} else {
	fmt.Println(result)
}

{map[singleton:{233555580689580553 0xc00009b410 0xc00009b410 <nil>}]}

try
{
    Value result = await client.Query(
        Singleton(Ref(Collection("posts"), "233286601218720256"))
    );
    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}

SetRefV(System.Collections.Generic.Dictionary`2[System.String,FaunaDB.Types.Value])

System.out.println(
    client.query(
        Singleton(Ref(Collection("posts"), "233286601218720256"))
    ).get()
);

{@set = {singleton: ref(id = "233286601218720256", collection = ref(id = "posts", collection = ref(id = "collections")))}}

Singleton(Ref(Collection('posts'), '233286601218720256'))

Singleton(Ref(Collection("posts"), "233286601218720256"))

Query metrics:

bytesIn: 70
bytesOut: 152
computeOps: 1
readOps: 0
writeOps: 0
readBytes: 0
writeBytes: 0
queryTime: 9ms
retries: 0

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