Choice States

A Choice state ("Type": "Choice") adds branching logic to a flow.

Choice states must contain a "Choices" field which is an array of "Choice Rules". Each Choice Rule contains a boolean expression and a "Next" field, containing the name of a state to which the flow should transition if the expression is true.

Choice states may contain a "Default", the name of a state to choose if none of the boolean expressions causes a transition. If none of the Choice Rules matches and a "Default" is not defined, the run will terminate with an error.

Choice rules are evaluated in order. The first rule which passes is evaluated and selects the next state.

Fields

Choices

An array of Choice Rules.

Default

The default state to transition to next if no rule in "Choices" matches.

Choice Rules

There are many distinct Choice Rules, each of which encodes a different boolean check.

Using And, Or, and Not Choice Rules, these rules can be nested.

Rules must include a Next field, declaring the state to which the flow will transition if the rule is matched. However, nested rules may not include Next — it is allowed and required only at the top level of the Choices array.

Each rule type requires its own documentation.

"And" Rules

An And rule contains an "And", an array of nested Choice Rules. The rule evaluates to true if all of the rules in the array evaluate to true.

"Or" Rules

An Or rule contains an "Or", an array of nested Choice Rules. The rule evaluates to true if any of the rules in the array evaluate to true.

"Not" Rules

An Not rule contains a "Not", a single nested Choice Rule. The rule evaluates to true if the nested rule evaluates to false.

Variable Rules

A Variable Rule contains two fields.

One is always "Variable", a JSONPath expression which indicates a value in the state input which is evaluated by this rule.

The other field on a Variable Rule is one of the following:

BooleanEquals

A value, true or false, to which the Variable is compared.

BooleanEqualsPath

A JSONPath expression which indicates the location of a value in the input. The value is used as in BooleanEquals.

IsBoolean

Contains a boolean value. When true, evaluates to true if the Variable is true or false, false if it has any other value. When false, the meaning is inverted.

IsNull

Contains a boolean value. When true, evaluates to true if the Variable is null, false if it has any other value. When false, the meaning is inverted.

IsNumeric

Contains a boolean value. When true, evaluates to true if the Variable is an integer or float, false otherwise. When false, the meaning is inverted.

IsPresent

Contains a boolean value. When true, evaluates to true if the expression in Variable points to a valid location in the payload, false otherwise. When false, the meaning is inverted.

IsString

Contains a boolean value. When true, evaluates to true if the Variable is a string, false otherwise. When false, the meaning is inverted.

IsTimestamp

Contains a boolean value. When true, evaluates to true if the Variable is a string formatted as a timestamp, false otherwise. When false, the meaning is inverted.

NumericEquals

Contains a numeric value. Evaluates to true if the Variable matches the value, false otherwise.

NumericEqualsPath

Contains a JSONPath to a value in the input. The value is used as in NumericEquals.

NumericGreaterThan

Contains a numeric value. Evaluates to true if the Variable is greater than the value, false otherwise.

NumericGreaterThanPath

Contains a JSONPath to a value in the input. The value is used as in NumericGreaterThan.

NumericGreaterThanEquals

Contains a numeric value. Evaluates to true if the Variable is greater than or equal to the value, false otherwise.

NumericGreaterThanEqualsPath

Contains a JSONPath to a value in the input. The value is used as in NumericGreaterThanEquals.

NumericLessThan

Contains a numeric value. Evaluates to true if the Variable is less than the value, false otherwise.

NumericLessThanPath

Contains a JSONPath to a value in the input. The value is used as in NumericLessThan.

NumericLessThanEquals

Contains a numeric value. Evaluates to true if the Variable is less than or equal to the value, false otherwise.

NumericLessThanEqualsPath

Contains a JSONPath to a value in the input. The value is used as in NumericLessThanEquals.

StringEquals

Contains a string value. Evaluates to true if the Variable is equal to the value, false otherwise.

StringEqualsPath

Contains a JSONPath to a value in the input. The value is used as in StringEquals.

StringGreaterThan

Contains a string value. Evaluates to true if the Variable is comes after the value lexicographically, false otherwise.

StringGreaterThanPath

Contains a JSONPath to a value in the input. The value is used as in StringGreaterThan.

StringGreaterThanEquals

Contains a string value. Evaluates to true if the Variable is equal to or comes after the value lexicographically, false otherwise.

StringGreaterThanEqualsPath

Contains a JSONPath to a value in the input. The value is used as in StringGreaterThanEquals.

StringLessThan

Contains a string value. Evaluates to true if the Variable comes before the value lexicographically, false otherwise.

StringLessThanPath

Contains a JSONPath to a value in the input. The value is used as in StringLessThan.

StringLessThanEquals

Contains a string value. Evaluates to true if the Variable is equal to or comes before the value lexicographically, false otherwise.

StringLessThanEqualsPath

Contains a JSONPath to a value in the input. The value is used as in StringLessThanEquals.

StringMatches

Contains a string value in the form of a pattern containing wildcards (*). Evaluates to true if the Variable matches the pattern, false otherwise.

TimestampEquals

Contains a string value containing an RFC3331 timestamp. Evaluates to true if the Variable matches the timestamp, false otherwise.

TimestampEqualsPath

Contains a JSONPath to a value in the input. The value is used as in TimestampEquals.

TimestampGreaterThan

Contains a string value containing an RFC3331 timestamp. Evaluates to true if the Variable is later than the timestamp, false otherwise.

TimestampGreaterThanPath

Contains a JSONPath to a value in the input. The value is used as in TimestampGreaterThan.

TimestampGreaterThanEquals

Contains a string value containing an RFC3331 timestamp. Evaluates to true if the Variable is equal to or later than the timestamp, false otherwise.

TimestampGreaterThanEqualsPath

Contains a JSONPath to a value in the input. The value is used as in TimestampGreaterThanEquals.

TimestampLessThan

Contains a string value containing an RFC3331 timestamp. Evaluates to true if the Variable is before than the timestamp, false otherwise.

TimestampLessThanPath

Contains a JSONPath to a value in the input. The value is used as in TimestampLessThan.

TimestampLessThanEquals

Contains a string value containing an RFC3331 timestamp. Evaluates to true if the Variable is equal to or earlier than the timestamp, false otherwise.

TimestampLessThanEqualsPath

Contains a JSONPath to a value in the input. The value is used as in TimestampLessThanEquals.

Examples 

{
  "Type": "Choice",
  "Choices": [
    {
      "Variable": "$.reader_choice",
      "StringEqualsPath": "$.novel_definition_of_villany",
      "Next": "VillanousEnding"
    },
    {
      "And": [
        {
          "Variable": "$.is_star_wars_novel",
          "BooleanEquals": true
        },
        {
          "Variable": "$.reader_choice",
          "StringEquals": "GoToTosheStation"
        }
      ],
      "Next": "GoodEnding"
    },
    {
      "And": [
        {
          "Or": [
            {
              "Variable": "$.is_harry_potter_novel",
              "BooleanEquals": true
            },
            {
              "Variable": "$.has_arthurian_setting",
              "BooleanEquals": true
            }
          ]
        },
        {
          "Variable": "$.reader_choice",
          "StringEquals": "LearnMagic"
        }
      ],
      "Next": "GoodEnding"
    }
  ],
  "Default": "BadEnding"
}