YQL to JSON type mapping
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Updated at July 1, 2026
The following rules apply when converting YQL types to JSON types.
Scalar types
| YQL type | JSON type | JSON example |
|---|---|---|
Int8, Int16, Int32Uint8, Uint16, Uint32 |
Integer | 647713 |
Int64, Uint64 |
Integer if the value is in the range [-(253-1) ... (253-1)]; otherwise, String | -9007199254740991 "-9007199254740991" "10446744073709551615" |
Bool |
Bool | True |
Float, Double |
Double NaN and Inf (written as String) |
7,88731023 "nan" "inf" |
Decimal |
String | "45,23410083" |
String |
Base64 string (string as a byte array) | "0LDQsdGB0ZHQmWFiYw==" |
Utf8 |
String | "String text" |
Complex types
| YQL type | JSON type | JSON example |
|---|---|---|
Json, JsonDocument |
String (whole node serialized to a string) | "{\"a\":[1,2,3]}" |
Date, Datetime, Timestamp |
String in ISO-8601 format | "2022-02-09" "2021-01-01T14:05:43Z" "2022-02-13T12:26:52.879622Z" |
Interval |
String in ISO-8601 format | "PT1M" |
Optional types
| YQL type | JSON type | JSON example |
|---|---|---|
Optional |
Array [] | []: Nothing [10]: Just 10 |
Optional type nesting is preserved: Just(Just(Just(10))): [[[10]]].
Containers
| YQL type | JSON type | JSON example |
|---|---|---|
List<Type> |
Array | [1,2,3,4] |
Dict<KeyType, ValueType> |
Array of arrays | [[key1, value1], [key2, value2]] |
Set<KeyType> |
Array | [key_value1, key_value2] |
Tuple<Type1, Type2> |
Array | [element1, element2, ..] []: Empty tuple |
Struct<Name:Utf8,Age:Int32> |
Object {} | { "Name": "John", "Age": 128 } |
Variant<Type1, Type2> with a tuple |
Two-element array: [filled_index, Value_by_index] | Variant<Utf8, Int32> Variant(64563, 1) — [1, 64563] |
Variant<value:Int32,error:String> structured string |
Two-element array: [filled_index, Value_by_index] | Variant<complete:Bool,error:Utf8> Variant(false, "complete") — ["complete", false] |
Special types
| YQL type | JSON type |
|---|---|
Void, Null |
Null |
EmptyList, EmptyDict |
[] |
Tagged |
The original type is preserved, but the custom tag name is lost |