Pragma options

The $pragma keyword is used to override settings for the current execution context. The value of the $pragma keyword must be an object. Available properties are described below.

You can disable $pragma keyword by setting the allowPragmas option to false.


Sets the current global variables.

  "$pragma": {
    "globals": {
      "VALUE-1": 1,
      "OTHER-GLOBAL": "something"


Sets the current slots. If a slot value is passed as a string, a slot with that name is search and used if exists.

  "$pragma": {
    "slots": {
      "part-mail": {"format": "email"},
      "part-props": "some-existing-slot-name"


Overrides the maxErrors setting. The value must be a positive integer.


Converts current value by applying a cast. The value must be a string representing a JSON data type name (except null).

  "$pragma": {
    "cast": "number"
  "type": "number",
  "minimum": 5

If you send "5.1" (string), the value will be converted to 5.1 (float) and then validated. Without the cast, an error is returned by the type keyword.

The following table describes various casts.

If a conversion is not available, the value is converted to null.

From To Result
null number 0 - zero
null integer 0 - zero
null boolean false
null string "" - empty string
null array [] - empty array
null object null
number number same value
number integer truncates number, 5.1 => 5
number boolean false if 0, true otherwise
number string string representation, 5.1 => "5.1"
number array 5.1 => [5.1]
number object null
integer number same value
integer integer same value
integer boolean false if 0, true otherwise
integer string string representation, 5 => "5"
integer array 5 => [5]
integer object null
boolean number true => 1, false => 0
boolean integer true => 1, false => 0
boolean boolean same value
boolean string true => "1", false => "" - empty string
boolean array true => [true], false => false
boolean object null
string number try to parse the number from string, 0 if invalid number representation
string integer try to parse the integer from string, 0 if invalid number representation
string boolean empty string => false, otherwise true
string string same value
string array "str" => ["str"]
string object null
array number null
array integer null
array boolean empty array => false, otherwise true
array string null
array array same value
array object object representation, [1, "abc"] => {"0": 1, "1": "abc"}
object number null
object integer null
object boolean empty object => false, otherwise true
object string null
object array object values, {"key1": 1, "key2": "value 2"} => [1, "value 2"]
object object same value
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