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`IsKey`

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

IsKey( value )

is_key( value )

IsKey( value )

IsKey( value )

IsKey( value )

Description

The IsKey function returns true only if value is a key, otherwise it returns false.

Parameters

Parameter Type Definition and Requirements

Parameter	Type	Definition and Requirements
`value`	Any	Any value, which is to be tested to determine whether it is a key or not.

value

Any

Any value, which is to be tested to determine whether it is a key or not.

Returns

Returns a Boolean, indicating whether value was a key or not.

Examples

The following query uses Map to iterate over an array of all of the types of values that can be tested by a type-check function, passing each item into a Lambda function that returns an object, which contains the value and the result of calling IsKey with that value:

client.query(
  q.Map(
    [
      ['array'],
      true,
      false,
      new Uint8Array([1, 2, 3, 4]),
      [0x1, 0x2, 0x3, 0x4],
      q.Collection('Letters'),
      q.Ref('credentials/self'),
      q.Database('child_db'),
      q.Date('2019-11-12'),
      q.Ref(q.Collection('Letters'), 123),
      10.1,
      q.Function('double'),
      q.Index('letters'),
      10,
      q.Ref(q.Keys(), '1'),
      q.Query(q.Lambda('x', q.Var('x'))),
      null,
      { x: 10 },
      q.Role('employees'),
      q.Match(q.Index('letters')),
      'ten',
      '10',
      q.Time('2020-07-06T12:34:56.789Z'),
      q.Ref(q.Tokens(), '1'),
    ],
    q.Lambda('x', {
      value: q.Var('x'),
      IsKey: q.IsKey(q.Var('x')),
    })
  )
)
.then((ret) => console.log(ret))
.catch((err) => console.error(
  'Error: [%s] %s: %s',
  err.name,
  err.message,
  err.errors()[0].description,
))

[
  { value: [ 'array' ], IsKey: false },
  { value: true, IsKey: false },
  { value: false, IsKey: false },
  { value: Bytes("AQIDBA=="), IsKey: false },
  { value: [ 1, 2, 3, 4 ], IsKey: false },
  { value: Collection("Letters"), IsKey: false },
  { value: Ref(Credentials(), "268432612451680768"), IsKey: false },
  { value: Database("child_db"), IsKey: false },
  { value: Date("2019-11-12"), IsKey: false },
  { value: Ref(Collection("Letters"), "123"), IsKey: false },
  { value: 10.1, IsKey: false },
  { value: Function("double"), IsKey: false },
  { value: Index("letters"), IsKey: false },
  { value: 10, IsKey: false },
  { value: Ref(Keys(), "1"), IsKey: true },
  { value: Query(Lambda("x", Var("x"))), IsKey: false },
  { value: null, IsKey: false },
  { value: { x: 10 }, IsKey: false },
  { value: Role("employees"), IsKey: false },
  { value: Match(Index("letters")), IsKey: false },
  { value: 'ten', IsKey: false },
  { value: '10', IsKey: false },
  { value: Time("2020-06-15T21:22:19.397Z"), IsKey: false },
  { value: Ref(Tokens(), "1"), IsKey: false }
]

result = client.query(
  q.map_(
    q.lambda_("x", {
      "value": q.var("x"),
      "IsKey": q.is_key(q.var("x")),
    }),
    [
      ["array"],
      True,
      False,
      bytearray([1, 2, 3, 4]),
      [0x1, 0x2, 0x3, 0x4],
      q.collection("Letters"),
      q.ref("credentials/self"),
      q.database("child_db"),
      q.date("2019-11-12"),
      q.ref(q.collection("Letters"), 123),
      10.1,
      q.function("double"),
      q.index("letters"),
      10,
      q.ref(q.keys(), "1"),
      q.query(q.lambda_("x", q.var("x"))),
      None,
      {"x": 10},
      q.role("employees"),
      q.match(q.index("letters")),
      "ten",
      "10",
      q.time("2020-07-06T12:34:56.789Z"),
      q.ref(q.tokens(), "1"),
    ],
  )
)
print(result)

[{'value': ['array'], 'IsKey': False}, {'value': True, 'IsKey': False}, {'value': False, 'IsKey': False}, {'value': bytearray(b'\x01\x02\x03\x04'), 'IsKey': False}, {'value': [1, 2, 3, 4], 'IsKey': False}, {'value': Ref(id=Letters, collection=Ref(id=collections)), 'IsKey': False}, {'value': Ref(id=282032258185953792, collection=Ref(id=credentials)), 'IsKey': False}, {'value': Ref(id=child_db, collection=Ref(id=databases)), 'IsKey': False}, {'value': datetime.date(2019, 11, 12), 'IsKey': False}, {'value': Ref(id=123, collection=Ref(id=Letters, collection=Ref(id=collections))), 'IsKey': False}, {'value': 10.1, 'IsKey': False}, {'value': Ref(id=double, collection=Ref(id=functions)), 'IsKey': False}, {'value': Ref(id=letters, collection=Ref(id=indexes)), 'IsKey': False}, {'value': 10, 'IsKey': False}, {'value': Ref(id=1, collection=Ref(id=keys)), 'IsKey': True}, {'value': Query({'api_version': '4', 'lambda': 'x', 'expr': {'var': 'x'}}), 'IsKey': False}, {'value': None, 'IsKey': False}, {'value': {'x': 10}, 'IsKey': False}, {'value': Ref(id=employees, collection=Ref(id=roles)), 'IsKey': False}, {'value': SetRef({'match': Ref(id=letters, collection=Ref(id=indexes))}), 'IsKey': False}, {'value': 'ten', 'IsKey': False}, {'value': '10', 'IsKey': False}, {'value': FaunaTime('2020-07-06T12:34:56.789Z'), 'IsKey': False}, {'value': Ref(id=1, collection=Ref(id=tokens)), 'IsKey': False}]

result, err := client.Query(
	f.Map(
		f.Arr{
			f.Arr{"array"},
			true,
			false,
			f.BytesV{0x01, 0x02, 0x03, 0x04},
			f.Arr{0x1, 0x2, 0x3, 0x4},
			f.Collection("Letters"),
			f.Ref("credentials/self"),
			f.Database("child_db"),
			f.Date("2019-11-12"),
			f.Ref(f.Collection("Letters"), 123),
			10.1,
			f.Function("double"),
			f.Index("letters"),
			10,
			f.Ref(f.Keys(), "1"),
			f.Query(f.Lambda("x", f.Var("x"))),
			nil,
			f.Null(),
			f.Obj{"x": 10},
			f.Role("employees"),
			f.Match(f.Index("letters")),
			"ten",
			"10",
			f.Time("2020-07-06T12:34:56.789Z"),
			f.Ref(f.Tokens(), "1"),
		},
		f.Lambda("x", f.Obj{
			"value": f.Var("x"),
			"IsKey": f.IsKey(f.Var("x")),
		})))

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

[map[IsKey:false value:[array]] map[IsKey:false value:true] map[IsKey:false value:false] map[IsKey:false value:[1 2 3 4]] map[IsKey:false value:[1 2 3 4]] map[IsKey:false value:{Letters 0xc00008ffb0 0xc00008ffb0 <nil>}] map[IsKey:false value:{280481857410171392 0xc00012e0f0 0xc00012e0f0 <nil>}] map[IsKey:false value:{child_db 0xc00012e210 0xc00012e210 <nil>}] map[IsKey:false value:{0 63709113600 <nil>}] map[IsKey:false value:{123 0xc000148150 0xc000148150 <nil>}] map[IsKey:false value:10.1] map[IsKey:false value:{double 0xc0001482a0 0xc0001482a0 <nil>}] map[IsKey:false value:{letters 0xc0001483c0 0xc0001483c0 <nil>}] map[IsKey:false value:10] map[IsKey:true value:{1 0xc000148510 0xc000148510 <nil>}] map[IsKey:false value:{[123 34 97 112 105 95 118 101 114 115 105 111 110 34 58 34 51 34 44 34 108 97 109 98 100 97 34 58 34 120 34 44 34 101 120 112 114 34 58 123 34 118 97 114 34 58 34 120 34 125 125]}] map[IsKey:false value:{}] map[IsKey:false value:{}] map[IsKey:false value:map[x:10]] map[IsKey:false value:{employees 0xc000148720 0xc000148720 <nil>}] map[IsKey:false value:{map[match:{letters 0xc000148870 0xc000148870 <nil>}]}] map[IsKey:false value:ten] map[IsKey:false value:10] map[IsKey:false value:{789000000 63729635696 <nil>}] map[IsKey:false value:{1 0xc000148a20 0xc000148a20 <nil>}]]

try
{
    Value result = await client.Query(
        Map(
            Arr(
                Arr("array"),
                true,
                false,
                BytesV.Of(0x1, 0x2, 0x3, 0x4),
                Arr(0x1, 0x2, 0x3, 0x4),
                Collection("Letters"),
                Ref("credentials/self"),
                Database("child_db"),
                Date("2019-11-12"),
                Ref(Collection("Letters"), 123),
                10.1,
                Function("double"),
                Index("letters"),
                10,
                Ref(Keys(), "1"),
                Query(Lambda("x", Var("x"))),
                null,
                Obj("x", 10),
                Role("employees"),
                Match(Index("letters")),
                "ten",
                "10",
                Time("2020-07-06T12:34:56.789Z"),
                Ref(Tokens(), "1")
            ),
            Lambda(
                "x",
                Obj(
                    "value", Var("x"),
                    "IsKey", IsKey(Var("x"))
                )
            )
        )
    );

    Console.WriteLine(result);
}
catch (Exception e)
{
    Console.WriteLine($"ERROR: {e.Message}");
}

Arr(ObjectV(value: Arr(StringV(array)),IsKey: BooleanV(False)), ObjectV(value: BooleanV(True),IsKey: BooleanV(False)), ObjectV(value: BooleanV(False),IsKey: BooleanV(False)), ObjectV(value: BytesV(0x01, 0x02, 0x03, 0x04),IsKey: BooleanV(False)), ObjectV(value: Arr(LongV(1), LongV(2), LongV(3), LongV(4)),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "Letters", collection = RefV(id = "collections")),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "295432898045018624", collection = RefV(id = "credentials")),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "child_db", collection = RefV(id = "databases")),IsKey: BooleanV(False)), ObjectV(value: FaunaDate(2019-11-12 12:00:00 AM),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "123", collection = RefV(id = "Letters", collection = RefV(id = "collections"))),IsKey: BooleanV(False)), ObjectV(value: DoubleV(10.1),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "double", collection = RefV(id = "functions")),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "letters", collection = RefV(id = "indexes")),IsKey: BooleanV(False)), ObjectV(value: LongV(10),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "1", collection = RefV(id = "keys")),IsKey: BooleanV(True)), ObjectV(value: QueryV(System.Collections.Generic.Dictionary`2[System.String,FaunaDB.Query.Expr]),IsKey: BooleanV(False)), ObjectV(value: NullV,IsKey: BooleanV(False)), ObjectV(value: ObjectV(x: LongV(10)),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "employees", collection = RefV(id = "roles")),IsKey: BooleanV(False)), ObjectV(value: SetRefV(System.Collections.Generic.Dictionary`2[System.String,FaunaDB.Types.Value]),IsKey: BooleanV(False)), ObjectV(value: StringV(ten),IsKey: BooleanV(False)), ObjectV(value: StringV(10),IsKey: BooleanV(False)), ObjectV(value: FaunaTime(2020-07-06T12:34:56.789Z),IsKey: BooleanV(False)), ObjectV(value: RefV(id = "1", collection = RefV(id = "tokens")),IsKey: BooleanV(False)))

Map(
  [
    ['array'],
    true,
    false,
    new Uint8Array([1, 2, 3, 4]),
    [0x1, 0x2, 0x3, 0x4],
    Collection('Letters'),
    Ref('credentials/self'),
    Database('child_db'),
    Date('2019-11-12'),
    Ref(Collection('Letters'), 123),
    10.1,
    Function('double'),
    Index('letters'),
    10,
    Ref(Keys(), '1'),
    Query(Lambda('x', Var('x'))),
    null,
    { x: 10 },
    Role('employees'),
    Match(Index('letters')),
    'ten',
    '10',
    Time('2020-07-06T12:34:56.789Z'),
    Ref(Tokens(), '1'),
  ],
  Lambda('x', {
    value: Var('x'),
    IsKey: IsKey(Var('x')),
  })
)

[
  { value: [ 'array' ], IsKey: false },
  { value: true, IsKey: false },
  { value: false, IsKey: false },
  { value: { '0': 1, '1': 2, '2': 3, '3': 4 }, IsKey: false },
  { value: [ 1, 2, 3, 4 ], IsKey: false },
  { value: Collection("Letters"), IsKey: false },
  { value: Ref(Credentials(), "302043979982045696"), IsKey: false },
  { value: Database("child_db"), IsKey: false },
  { value: Date("2019-11-12"), IsKey: false },
  { value: Ref(Collection("Letters"), "123"), IsKey: false },
  { value: 10.1, IsKey: false },
  { value: Function("double"), IsKey: false },
  { value: Index("letters"), IsKey: false },
  { value: 10, IsKey: false },
  { value: Ref(Keys(), "1"), IsKey: true },
  { value: Query(Lambda("x", Var("x"))), IsKey: false },
  { value: null, IsKey: false },
  { value: { x: 10 }, IsKey: false },
  { value: Role("employees"), IsKey: false },
  { value: Match(Index("letters")), IsKey: false },
  { value: 'ten', IsKey: false },
  { value: '10', IsKey: false },
  { value: Time("2020-07-06T12:34:56.789Z"), IsKey: false },
  { value: Ref(Tokens(), "1"), IsKey: false }
]

Query metrics:

bytesIn: 594
bytesOut: 1,511
computeOps: 2
readOps: 0
writeOps: 0
readBytes: 373
writeBytes: 0
queryTime: 24ms
retries: 0

This query operates on a pre-existing schema, which is not provided here.

Also, the query is executed via a client connection, that uses a secret acquired by calling the Login function (not shown here), so that Ref("credentials/self") returns a valid value.

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IsKey

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Returns

Examples

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`IsKey`