Filtering by Relationships

Structural filters work on properties of a single object. Relationship filters work across objects — linking instances to their types, types to their families, and resolving data that lives one level up from where you need it.

In DAQS, relationships are not implicit. The data model is flat. Every connection must be expressed explicitly using parent.id and lookup patterns.

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What you will learn

• How to filter FamilyInstance objects by category via their FamilySymbol parent
• How to resolve shared parameters that may exist on either the instance or the type

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Pages in this section

Filter Instances via Symbol Categories

The canonical pattern for filtering placed elements by category across multiple categories. Combines an inclusion list, symbol filtering, and instance filtering via parent.id.

Instance Parameter from Type

How to retrieve a shared parameter that may be stored on either the FamilyInstance or the FamilySymbol. Introduces the effective parameter pattern and GUID-based lookup.

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Prerequisites

You should already understand:

• Why category filtering belongs on the FamilySymbol — see Revit Object Hierarchy
• The two-step filtering pattern — see Two-Step Filtering
• Inclusion lists and the in operator — see Filter by Category — Inclusion List

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If you filter instances directly, you are probably skipping a required relationship step.