revit-selection-filter

name	revit-selection-filter
description	Filter which elements and references a user can pick in Autodesk Revit UI with the Nice3point.Revit.Toolkit SelectionConfiguration, not a hand-rolled ISelectionFilter. USE FOR: constraining an interactive Selection.PickObject/PickObjects with a fluent Allow.Element / Allow.Reference filter. DO NOT USE FOR: headless API callbacks such as family load or duplicate-type options (use Toolkit option handlers like FamilyLoadOptions).
license	MIT

Revit Selection Filter

Selection.PickObject takes an ISelectionFilter that decides what the user may pick. SelectionConfiguration (from Nice3point.Revit.Toolkit) builds that filter from two lambdas; you do not hand-roll a class. It drives an interactive pick and needs the Revit UI.

When to use

• Restricting an interactive pick to a category, type, or geometry kind.

When not to use

• Constraining a headless API callback such as family load or duplicate-type options — use a Toolkit option handler like FamilyLoadOptions.

Workflow

Step 1: Configure the allowed elements and references

Allow.Element gates which elements are pickable; Allow.Reference gates which references (faces, edges, points). Set either or both — each returns the configuration and they chain — then pass configuration.Filter to the pick call.

var configuration = new SelectionConfiguration()
    .Allow.Element(element => element.Category.Id.IsCategory(BuiltInCategory.OST_Walls))
    .Allow.Reference((reference, position) => false);

var picked = uiDocument.Selection.PickObject(ObjectType.Element, configuration.Filter);

Step 2: Verify

Run the command and confirm only the intended elements or references highlight and accept a pick.

Validation

• The filter uses SelectionConfiguration, not a hand-rolled ISelectionFilter.
• Allow.Element/Allow.Reference express the rule with a lambda, not a new class.

Common Pitfalls

Pitfall	Correct approach
A bespoke ISelectionFilter for a category check	Use SelectionConfiguration().Allow.Element(...).
Filtering references with an element-only filter	Add Allow.Reference((reference, position) => ...).
SelectionConfiguration not found	The Nice3point.Revit.Toolkit package is not referenced.