$getSharedParamBool

Reads a boolean shared parameter from an object. Returns true, false, or null — never the raw numeric value (0/1) that Revit stores internally.

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Definition

$getSharedParamBool := function($object, $logicalName){
  (
    $guid := $lookup($paramGuids, $logicalName);
    $sp   := $guid and $exists($object.values)
              ? $lookup($object.values, "p_" & $guid)
              : undefined;

    $exists($sp)
      ? (
          $exists($sp.value)
            ? $boolean($sp.value)
            : null
        )
      : null
  )
};

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Dependencies

Requires $paramGuids in the outer scope:

$paramGuids := {
  "IsExternal":  "576da907-5f75-40ce-a0c1-572ca690fc1b",
  "IsExternal2": "28fecb30-be2a-40c6-9fb0-703be83c5e9f"
};

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Parameters

Parameter	Type	Description
$object	object	The element to read from (pass $ for current element)
$logicalName	string	The key in $paramGuids

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Return value

Situation	Returns
Parameter exists, value = 1	true
Parameter exists, value = 0	false
Parameter exists, no value	null
Parameter absent	null

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Why $boolean() is needed

Revit stores boolean parameter values as numbers: 1 for true, 0 for false. Without $boolean(), the value 0 is truthy in some JSONata comparisons. Converting explicitly makes the intent clear and the behaviour reliable.

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Usage

$[type = "FamilyInstance" and $exists(parent)].{
  "id": id,
  "name": name,
  "IsExternal": $getSharedParamBool($, "IsExternal")
}

Validator: IsExternal → bool:Is true

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Used in rules

• rule-eb5d3f9a — Function is null → IsExternal → true