Formula use cases

Formulas can be used in several product areas to calculate values, decide whether actions should run, choose notification recipients, and convert measurement units. Each formula context exposes a specific set of variables.

Preferred Unit Conversion

See Measurement profile settings for more information

This use case converts a raw source measurement value into a preferred display unit. The formula must return a number.

Available variables:

Variable	Path	Value
`SOURCE`	`["SOURCE"]`	The raw numeric source value being converted.

Example using SOURCE:

JSON

{
  "type": "arithmeticOperation",
  "operator": "*",
  "operands": [
    { "type": "variable", "path": ["SOURCE"] },
    { "type": "constant", "value": 0.001 }
  ]
}

Reverse Preferred Unit Conversion

See Measurement profile settings for more information

This use case converts a preferred-unit value back into the raw source unit. The formula must return a number.

Available variables:

Variable	Path	Value
`PREFERRED`	`["PREFERRED"]`	The numeric value in the preferred unit.

Example using PREFERRED:

JSON

{
  "type": "arithmeticOperation",
  "operator": "/",
  "operands": [
    { "type": "variable", "path": ["PREFERRED"] },
    { "type": "constant", "value": 0.001 }
  ]
}

Calculated Asset Attributes

This use case calculates asset custom_data attributes from formulas defined on an asset type schema. The formula is evaluated against the merged incoming and existing asset data.

Available variables:

Variable	Path	Value
`asset`	`["asset"]`	The current asset being evaluated. Common custom data paths look like `["asset", "custom_data", "<property>"]`.
`childrenOfType`	`["childrenOfType"]` with `params.type`	Descendant assets of the requested asset type in the current asset tree. Each child includes `id`, `type`, `label`, `latitude`, `longitude`, and `custom_data`.

Example using asset:

Screenshot 2026-05-05 at 11.39.39 AM.png

JSON

{
  "type": "arithmeticOperation",
  "operator": "+",
  "operands": [
    { "type": "variable", "path": ["asset", "custom_data", "temperature"] },
    { "type": "constant", "value": 5 }
  ]
}

Example using childrenOfType:

Screenshot 2026-05-05 at 11.40.22 AM.png

JSON

{
  "type": "aggregateFunction",
  "operator": "sum",
  "operands": [
    {
      "type": "arrayFunction",
      "operator": "map",
      "operands": [
        {
          "type": "variable",
          "path": ["childrenOfType"],
          "params": { "type": "lightBulb" }
        },
        { "type": "variable", "path": ["$arrayItem", "custom_data", "energyUsage"] }
      ]
    }
  ]
}

Notification Recipient Formula

This use case computes notification recipients for email and SMS actions. The formula runs against the trigger message. It may return a comma-separated string or an array of strings.

Available variables:

Variable	Path	Value
`entity`	`["entity"]`	The trigger message for the action. Common custom data paths look like `["entity", "custom_data", "<property>"]`.

Example using entity:

Screenshot 2026-05-05 at 11.44.23 AM.png

JSON

{
  "type": "conditionalFunction",
  "operator": "if",
  "operands": [
    { "type": "variable", "path": ["entity", "custom_data", "sendToSupervisor"] },
    { "type": "variable", "path": ["entity", "custom_data", "supervisorEmail"] },
    { "type": "constant", "value": "ops@example.com" }
  ]
}

Rule Event Attribute Formula

This use case calculates custom event attributes for a rule-created event. The formula runs against the incoming entity and stores the result under the configured event attribute name.

Available variables:

Variable	Path	Value
`entity`	`["entity"]`	The incoming entity that triggered the rule. Common custom data paths look like `["entity", "custom_data", "<property>"]`.

Example using entity:

Screenshot 2026-05-05 at 11.50.45 AM.png

JSON

{
  "type": "arithmeticOperation",
  "operator": "+",
  "operands": [
    { "type": "variable", "path": ["entity", "custom_data", "pressure"] },
    { "type": "constant", "value": 42 },
  ]
}

Action Enabled Formula

This use case decides whether an action should run. The formula runs against the rule trigger message and must return a boolean. A null or undefined result disables the action.

Available variables:

Variable	Path	Value
`entity`	`["entity"]`	The trigger message for the rule action. Common custom data paths look like `["entity", "custom_data", "<property>"]`.

Example using entity:

Screenshot 2026-05-05 at 11.54.36 AM.png

JSON

{
  "type": "logicalOperation",
  "operator": "AND",
  "operands": [
    { "type": "variable", "path": ["entity", "custom_data", "notificationsEnabled"] },
    {
      "type": "comparisonOperation",
      "operator": ">=",
      "operands": [
        { "type": "variable", "path": ["entity", "custom_data", "severity"] },
        { "type": "constant", "value": 3 }
      ]
    }
  ]
}

Rule Expression Condition Evaluation

This use case evaluates rule expression conditions. The formula must return a boolean. Variables with paths like ["entity", "custom_data", "<property>"] identify the custom data fields required for evaluation.

Available variables:

Variable	Path	Value
`entity`	`["entity"]`	The incoming entity or related entity being evaluated by the rule condition. Common custom data paths look like `["entity", "custom_data", "<property>"]`.

Example using entity:

Screenshot 2026-05-05 at 11.58.04 AM.png

JSON

{
  "type": "comparisonOperation",
  "operator": "<",
  "operands": [
    { "type": "variable", "path": ["entity", "custom_data", "pressure"] },
    { "type": "variable", "path": ["entity", "custom_data", "pressureThreshold"] }
  ]
}