JSON Decision Model (JDM) Schema Reference

PyRulesEngine acts as a direct structural interpretation of the standardized JSON rules schema. Configurations can be authored fluidly in both JSON and YAML.

Core Object Hierarchy

A workflow array expects top level Workflow definitions.

[
  {
    "WorkflowName": "MyUniqueWorkflow",
    "Version": "1.0.0",
    "Rules": [
       ...
    ]
  }
]

Rule Fields

Each Rule object represents a decision evaluation node.

Field	Type	Description
RuleName	String	A unique name defining the node block in the workflow sequence.
RuleExpressionType	Enum	The execution evaluator format: "LambdaExpression", "Error". Default LambdaExpression.
Operator	Enum	Logical aggregator for child sub-rules. Options: And, AndAlso, Or, OrElse. Default: None
Expression	String	The actual CEL (Common Expression Language) conditional snippet. Required if Operator is omitted. Supports built-in math: abs, min, max, round.
SuccessEvent	String	A custom string returned in the payload upon successful evaluation mapping.
ErrorMessage	String	A custom string returned in the payload upon failure mapping.
Enabled	Boolean	True (default) evaluates the rule. False bypasses it proactively.
Rules	Array	Only used alongside an Operator wrapper to create multi-rule chains.
LocalParams	Array	Variable injection overriding or mapping specific inputs to shorter aliases.
Actions	Object	Triggers side effects OnSuccess or OnFailure.

Google CEL Syntax Rule

PyRulesEngine expressions follow strictly Google's Common Expression Language (CEL) syntax. Key departures from legacy engines include: - Case-Sensitive Booleans: Must be lowercase true or false. - Logical Operators: Use && (and), || (or), and ! (not). - Equality: Use == and !=. - Built-in Functions: - abs(x): Absolute value of a number. - min(a, b, ...): Minimum of a sequence. - max(a, b, ...): Maximum of a sequence. - round(x): Rounds to nearest integer. - Macros: Use .exists(), .all(), .filter(), and .map() for collection processing.

Actions

You can execute chained implementations natively upon rule resolution using the Actions array.

"Actions": {
  "OnSuccess": {
    "Name": "ExecuteWorkflow",
    "Context": {
      "WorkflowName": "NotificationFlow"
    }
  },
  "OnFailure": {
    "Name": "EvaluateRule",
    "Context": {
      "WorkflowName": "FallbackFlow",
      "RuleName": "DefaultBehavior"
    }
  }
}

The system ships with two native actions: * ExecuteWorkflow: Chute outputs and results into an entirely different file or defined Workflow schema recursively. * EvaluateRule: Jump specifically into a targeted, named isolated Rule node from any registered workflow.

(Note: Custom plugins can be mapped by registering action classes derived from ActionBase to the engine's Action Registry).

Aggregator Operators (And, AndAlso, Or, OrElse)

When constructing branching logic, PyRulesEngine schemas act as a tree. The top-level Operator decides how to fold the Rules array.

• And: Evaluates all rules, ensuring every single returning result is True.
• AndAlso: Identical to And, but instantly shorts out and skips future checks the moment any child rule evaluates to False.
• Or: Evaluates all rules, passing if at least one returned True.
• OrElse: Identical to Or, but instantly short-circuits to pass the moment any child rule evaluates to True.

RuleName: "IsSafeToProceed"
Operator: "AndAlso"
SuccessEvent: "System Nomimal"
Rules:
  - RuleName: "EnvironmentIsProd"
    Expression: "config.env == 'production'"
  - RuleName: "TokensAreValid"
    Expression: "secret.validity > 0"

RuleExpressionType (LambdaExpression vs DecisionTable vs Switch)

• LambdaExpression: (Default) Returns whatever mathematical/logical truth the Expression returns.

To act as an explicit "Blocker" or "Kill Switch", you would map a LambdaExpression with ErrorType: Error (which is the default). If True, the Rule Engine deliberately fails the rule.

{
  "RuleName": "DenyBlacklistedIP",
  "RuleExpressionType": "LambdaExpression",
  "ErrorType": "Error",
  "Expression": "network.ip in ['192.168.1.1', '10.0.0.5']",
  "ErrorMessage": "IP is blacklisted. Access denied."
}

Parameter Aliasing (LocalParams)

Useful for avoiding deeply nested schema repetitions in Lambda expressions. Instead of referencing invoice.payment.gateway.status, define a local alias.

RuleName: ValidatePayment
RuleExpressionType: LambdaExpression
LocalParams:
  - Name: status
    Expression: invoice.payment.gateway.status
Expression: status == "SUCCESS"