Data types - AWS IoT Core
Conversions

Data types

The AWS IoT rules engine supports all JSON data types.

Supported data types
Type Meaning
Int A discrete Int. 34 digits maximum.
Decimal

A Decimal with a precision of 34 digits, with a minimum non-zero magnitude of 1E-999 and a maximum magnitude 9.999...E999.

Note

Some functions return Decimal values with double precision rather than 34-digit precision.

With SQL V2 (2016-03-23), numeric values that are whole numbers, such as 10.0, are processed as an Int value (10) instead of the expected Decimal value (10.0). To reliably process whole number numeric values as Decimal values, use SQL V1 (2015-10-08) for the rule query statement.
Boolean True or False.
String A UTF-8 string.
Array A series of values that don't have to have the same type.
Object A JSON value consisting of a key and a value. Keys must be strings. Values can be any type.
Null Null as defined by JSON. It's an actual value that represents the absence of a value. You can explicitly create a Null value by using the Null keyword in your SQL statement. For example: "SELECT NULL AS n FROM 'topic/subtopic'"
Undefined

Not a value. This isn't explicitly representable in JSON except by omitting the value. For example, in the object {"foo": null}, the key "foo" returns NULL, but the key "bar" returns Undefined. Internally, the SQL language treats Undefined as a value, but it isn't representable in JSON, so when serialized to JSON, the results are Undefined.

 {"foo":null, "bar":undefined}

is serialized to JSON as:

 {"foo":null}

Similarly, Undefined is converted to an empty string when serialized by itself. Functions called with invalid arguments (for example, wrong types, wrong number of arguments, and so on) return Undefined.

Conversions

The following table lists the results when a value of one type is converted to another type (when a value of the incorrect type is given to a function). For example, if the absolute value function "abs" (which expects an Int or Decimal) is given a String, it attempts to convert the String to a Decimal, following these rules. In this case, 'abs("-5.123")' is treated as 'abs(-5.123)'.

Note

There are no attempted conversions to Array, Object, Null, or Undefined.

To decimal
Argument type Result
Int A Decimal with no decimal point.
Decimal The source value.
Boolean Undefined. (You can explicitly use the cast function to transform true = 1.0, false = 0.0.)
String The SQL engine tries to parse the string as a Decimal. AWS IoT attempts to parse strings matching the regular expression:^-?\d+(\.\d+)?((?i)E-?\d+)?$. "0", "-1.2", "5E-12" are all examples of strings that are converted automatically to Decimals.
Array Undefined.
Object Undefined.
Null Null.
Undefined Undefined.
To int
Argument type Result
Int The source value.
Decimal The source value rounded to the nearest Int.
Boolean Undefined. (You can explicitly use the cast function to transform true = 1.0, false = 0.0.)
String The SQL engine tries to parse the string as a Decimal. AWS IoT attempts to parse strings matching the regular expression:^-?\d+(\.\d+)?((?i)E-?\d+)?$. "0", "-1.2", "5E-12" are all examples of strings that are converted automatically to Decimals. AWS IoT attempts to convert the String to a Decimal, and then truncates the decimal places of that Decimal to make an Int.
Array Undefined.
Object Undefined.
Null Null.
Undefined Undefined.
To Boolean
Argument type Result
Int Undefined. (You can explicitly use the cast function to transform 0 = False, any_nonzero_value = True.)
Decimal Undefined. (You can explicitly use the cast function to transform 0 = False, any_nonzero_value = True.)
Boolean The original value.
String "true"=True and "false"=False (case insensitive). Other string values are Undefined.
Array Undefined.
Object Undefined.
Null Undefined.
Undefined Undefined.
To string
Argument type Result
Int A string representation of the Int in standard notation.
Decimal A string representing the Decimal value, possibly in scientific notation.
Boolean "true" or "false". All lowercase.
String The original value.
Array The Array serialized to JSON. The resultant string is a comma-separated list, enclosed in square brackets. A String is quoted. A Decimal, Int, Boolean, and Null is not.
Object The object serialized to JSON. The resultant string is a comma-separated list of key-value pairs and begins and ends with curly braces. A String is quoted. A Decimal, Int, Boolean, and Null is not.
Null Undefined.
Undefined Undefined.