IsString

Not available in this language yet.
IsString( value )
IsString( value )
IsString( value )
Not available in this language yet.
IsString( value )

Description

The IsString function returns true only if value is a String, otherwise it returns false.

Parameters

Argument Type Definition and Requirements

value

Any

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

Returns

Returns a boolean, indicating whether value was a string 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 IsString with that value:

Not available in this language yet.
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.RefCollection(f.Collection("Letters"), 123),
      10.1,
      f.Function("double"),
      f.Index("all_letters"),
      10,
      f.RefCollection(f.Keys(), "248967241620521472"),
      f.Query(f.Lambda("x", f.Var("x"))),
      nil,
      f.Null(),
      f.Obj{ "x": 10 },
      f.Role("employees"),
      f.Match(f.Index("all_letters")),
      "ten",
      "10",
      f.Now(),
      f.RefCollection(f.Tokens(), "249062079147803136"),
    },
    f.Lambda("x", f.Obj{
      "value": f.Var("x"),
      "IsString": f.IsString(f.Var("x")),
    })))

if (err != nil) {
  fmt.Println(err)
} else {
  fmt.Println(result)
}
[map[IsString:false value:[array]] map[IsString:false value:true] map[IsString:false value:false] map[IsString:false value:[1 2 3 4]] map[IsString:false value:[1 2 3 4]] map[IsString:false value:{Letters 0xc0004472f0 0xc0004472f0 <nil>}] map[IsString:false value:{264354436692836874 0xc000447410 0xc000447410 <nil>}] map[IsString:false value:{child_db 0xc000447530 0xc000447530 <nil>}] map[IsString:false value:{0 63709113600 <nil>}] map[IsString:false value:{123 0xc000447cb0 0xc000447cb0 <nil>}] map[IsString:false value:10.1] map[IsString:false value:{double 0xc000447e00 0xc000447e00 <nil>}] map[IsString:false value:{all_letters 0xc000447f20 0xc000447f20 <nil>}] map[IsString:false value:10] map[IsString:false value:{248967241620521472 0xc0002c4090 0xc0002c4090 <nil>}] map[IsString:false value:{[123 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[IsString:false value:{}] map[IsString:false value:{}] map[IsString:false value:map[x:10]] map[IsString:false value:{employees 0xc0002c42a0 0xc0002c42a0 <nil>}] map[IsString:false value:{map[match:{all_letters 0xc0002c43f0 0xc0002c43f0 <nil>}]}] map[IsString:true value:ten] map[IsString:true value:10] map[IsString:false value:{835897000 63724302644 <nil>}] map[IsString:false value:{249062079147803136 0xc0002c45a0 0xc0002c45a0 <nil>}]]
System.out.println(
    client.query(
        Map(
            Arr(
                Arr(Value("array")),
                Value(true),
                Value(false),
                Value(new byte[] {0x1, 0x2, 0x3, 0x4}),
                Arr(Value(0x1), Value(0x2), Value(0x3), Value(0x4)),
                Collection("Letters"),
                Ref("credentials/self"),
                Database("child_db"),
                Date("2019-11-12"),
                Ref(Collection("Letters"), "123"),
                Value(10.1),
                Function("double"),
                Index("all_letters"),
                Value(10),
                Ref(Keys(), "248967241620521472"),
                Query(Lambda("x", Var("x"))),
                Null(),
                Obj("x", Value(10)),
                Role("employees"),
                Match(Index("all_letters")),
                Value("ten"),
                Value("10"),
                Now(),
                Ref(Tokens(), "249062079147803136")
            ),
            Lambda(
                "x",
                Obj("value", Var("x"), "IsString", IsString(Var("x")))
            )
        )
    ).get());
[{value: ["array"], IsString: false},
 {value: true, IsString: false},
 {value: false, IsString: false},
 {value: [0x01 0x02 0x03 0x04], IsString: false},
 {value: [1, 2, 3, 4], IsString: false},
 {value: ref(id = "Letters", collection = ref(id = "collections")),
  IsString: false},
 {value: ref(id = "248967019900174848", collection = ref(id = "credentials")),
  IsString: false},
 {value: ref(id = "child_db", collection = ref(id = "databases")),
  IsString: false},
 {value: 2019-11-12, IsString: false},
 {value: ref(id = "123", collection = ref(id = "Letters", collection = ref(id = "collections"))),
  IsString: false},
 {value: 10.1, IsString: false},
 {value: ref(id = "double", collection = ref(id = "functions")),
  IsString: false},
 {value: ref(id = "all_letters", collection = ref(id = "indexes")),
  IsString: false},
 {value: 10, IsString: false},
 {value: ref(id = "248967241620521472", collection = ref(id = "keys")),
  IsString: false},
 {value: QueryV({lambda=x, expr={var=x}}), IsString: false},
 {value: null, IsString: false},
 {value: {x: 10}, IsString: false},
 {value: ref(id = "employees", collection = ref(id = "roles")),
  IsString: false},
 {value: {@set = {match: ref(id = "all_letters", collection = ref(id = "indexes"))}},
  IsString: false},
 {value: "ten", IsString: true},
 {value: "10", IsString: true},
 {value: 2019-11-12T13:15:16.789Z, IsString: false},
 {value: ref(id = "249062079147803136", collection = ref(id = "tokens")),
  IsString: false}]
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('all_letters'),
      10,
      q.Ref(q.Keys(), '248967241620521472'),
      q.Query(q.Lambda('x', q.Var('x'))),
      null,
      { x: 10 },
      q.Role('employees'),
      q.Match(q.Index('all_letters')),
      'ten',
      '10',
      q.Now(),
      q.Ref(q.Tokens(), '249062079147803136'),
    ],
    q.Lambda('x', {
      value: q.Var('x'),
      IsString: q.IsString(q.Var('x')),
    })
  )
)
.then((ret) => console.log(ret))
[ { value: [ 'array' ], IsString: false },
  { value: true, IsString: false },
  { value: false, IsString: false },
  { value: Bytes("AQIDBA=="), IsString: false },
  { value: [ 1, 2, 3, 4 ], IsString: false },
  { value: Collection("Letters"), IsString: false },
  { value: Ref(Credentials(), "248967019900174848"),
    IsString: false },
  { value: Database("child_db"), IsString: false },
  { value: Date("2019-11-12"), IsString: false },
  { value: Ref(Collection("Letters"), "123"), IsString: false },
  { value: 10.1, IsString: false },
  { value: Function("double"), IsString: false },
  { value: Index("all_letters"), IsString: false },
  { value: 10, IsString: false },
  { value: Ref(Keys(), "248967241620521472"), IsString: false },
  { value: Query(Lambda("x", Var("x"))), IsString: false },
  { value: null, IsString: false },
  { value: { x: 10 }, IsString: false },
  { value: Role("employees"), IsString: false },
  { value: Match(Index("all_letters")), IsString: false },
  { value: 'ten', IsString: true },
  { value: '10', IsString: true },
  { value: Time("2019-11-12T13:15:16.789Z"), IsString: false },
  { value: Ref(Tokens(), "249062079147803136"), IsString: false } ]
Not available in this language yet.
println(Await.result(
  client.query(
    Map(
      Arr(
        Arr("array"),
        true,
        false,
        BytesV(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("all_letters"),
        10,
        Ref(Keys(), "248967241620521472"),
        Query(Lambda("x", Var("x"))),
        Null,
        Obj("x" -> 10),
        Role("employees"),
        Match(Index("all_letters")),
        "ten",
        "10",
        Now(),
        Ref(Tokens(), "249062079147803136")
      ),
      Lambda(
        "x",
        Obj( "value" -> Var("x"), "IsString" -> IsString(Var("x")))
      )
    )
  ),
  5.seconds
))
[{value: ["array"], IsString: false},
 {value: true, IsString: false},
 {value: false, IsString: false},
 {value: [0x01 0x02 0x03 0x04], IsString: false},
 {value: [1, 2, 3, 4], IsString: false},
 {value: ref(id = "Letters", collection = ref(id = "collections")),
  IsString: false},
 {value: ref(id = "248967019900174848", collection = ref(id = "credentials")),
  IsString: false},
 {value: ref(id = "child_db", collection = ref(id = "databases")),
  IsString: false},
 {value: 2019-11-12, IsString: false},
 {value: ref(id = "123", collection = ref(id = "Letters", collection = ref(id = "collections"))),
  IsString: false},
 {value: 10.1, IsString: false},
 {value: ref(id = "double", collection = ref(id = "functions")),
  IsString: false},
 {value: ref(id = "all_letters", collection = ref(id = "indexes")),
  IsString: false},
 {value: 10, IsString: false},
 {value: ref(id = "248967241620521472", collection = ref(id = "keys")),
  IsString: false},
 {value: {lambda: "x", expr: {var: "x"}}, IsString: false},
 {value: NullV, IsString: false},
 {value: {x: 10}, IsString: false},
 {value: ref(id = "employees", collection = ref(id = "roles")),
  IsString: false},
 {value: {@set = {match: ref(id = "all_letters", collection = ref(id = "indexes"))}},
  IsString: false},
 {value: "ten", IsString: true},
 {value: "10", IsString: true},
 {value:2019-11-12T13:15:16.789Z, IsString: false},
 {value: ref(id = "249062079147803136", collection = ref(id = "tokens")),
  IsString: false}]

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 Login (not shown here), so that Ref("credentials/self") returns a valid value.

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