manage-parameters

Manage Revit Parameters

Perform parameter operation:

"$ARGUMENTS"

Clarify before scripting

• Read or write? Read-only queries don't need a transaction.
• Which elements? All elements of a category, or a filtered subset?
• Which parameter? Ask for the exact name (case-sensitive) if the user mentions one.
• What value? String, number, yes/no, or element reference?

Read/write parameter script

import clr
clr.AddReference('RevitServices')
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager
clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *

# Unwrap Dynamo-wrapped elements if needed
clr.AddReference('RevitNodes')
import Revit
clr.ImportExtensions(Revit.Elements)

doc = DocumentManager.Instance.CurrentDBDocument

# ── Dynamo inputs ────────────────────────────────────────────────────────────
# IN[0] = list of Revit elements (from a Collector or upstream node)
# IN[1] = parameter name (string)
# IN[2] = new value (string/number) — omit or set to None for read-only
elements   = IN[0] if isinstance(IN[0], list) else [IN[0]]
param_name = IN[1]
new_value  = IN[2] if len(IN) > 2 else None

write_mode = new_value is not None
results    = []

try:
    if write_mode:
        TransactionManager.Instance.EnsureInTransaction(doc)

    for el in elements:
        # Unwrap Dynamo wrapper to native Revit element
        revit_el = el.InternalElement if hasattr(el, 'InternalElement') else el

        param = revit_el.LookupParameter(param_name)

        if param is None:
            results.append({'Id': revit_el.Id.IntegerValue, 'Status': 'NOT FOUND'})
            continue

        if not write_mode:
            # ── Read mode ───────────────────────────────────────────────────
            val = (param.AsValueString()
                   or param.AsString()
                   or str(param.AsDouble()))
            results.append({'Id': revit_el.Id.IntegerValue, param_name: val})
        else:
            # ── Write mode ──────────────────────────────────────────────────
            if param.IsReadOnly:
                results.append({'Id': revit_el.Id.IntegerValue, 'Status': 'READ ONLY'})
                continue

            st = param.StorageType
            if   st == StorageType.String:  param.Set(str(new_value))
            elif st == StorageType.Double:  param.Set(float(new_value))
            elif st == StorageType.Integer: param.Set(int(new_value))
            else:
                results.append({'Id': revit_el.Id.IntegerValue,
                                'Status': 'UNSUPPORTED TYPE: ' + str(st)})
                continue

            results.append({'Id': revit_el.Id.IntegerValue,
                            'Status': 'OK',
                            'New Value': new_value})

    if write_mode:
        TransactionManager.Instance.TransactionTaskDone()

    OUT = results

except Exception as e:
    if write_mode:
        TransactionManager.Instance.ForceCloseTransaction()
    import traceback
    OUT = 'ERROR: ' + str(e) + '\n' + traceback.format_exc()