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Options Providers

Paracore allows you to create dynamic, data-driven selection lists using Options Providers. This is the primary way to provide selection data to your parameters.

🤝 The Provider Convention​

To create an Options Provider for a parameter named X, you define a companion property named X_Options.

Type Matching Rule​

The return type of your Options Provider must match the type of your main parameter (e.g., List<string>, List<double>, or List<WallType>).

🔄 The Compute Workflow​

For providers that require processing, the UI follows a dynamic lifecycle triggered by the Compute (🔄) button.

Logic-Based Discovery​

The engine detects "Computable" providers by analyzing the complexity of the expression:

Provider TypeLogicUI Behavior
Static Provider=> ["A", "B"];Auto-Populated. No button; selection is ready instantly.
Dynamic Provider=> new FilteredElementCollector...Computable. Shows button; transforms on click.
Transformed Provider=> myStaticList.OrderBy(x=>x).ToList();Computable. Shows button; transforms on click.

🏗️ Dynamic Providers (Revit API)​

Use dynamic providers for fine-grained filtering that goes beyond standard magic extraction.

// In V3, we return the actual elements!
public class Params {
    public WallType MyWallType { get; set; }

    // Custom dynamic provider
    public List<WallType> MyWallType_Options => new FilteredElementCollector(Doc)
                .OfClass(typeof(WallType))
                .Cast<WallType>()
                .Where(wt => wt.Kind == WallKind.Basic)
                .ToList();
}

📦 Static Providers​

Use static providers for fixed choices.

public class Params {
    public double Grade { get; set; } = 94.0; 
    
    // Static literal provider (Auto-populated)
    public List<double> Grade_Options => [94.0, 69.7, 79.5];
}

💡 Best Practices​

  • Safety: Always prefer clicking Compute for dynamic providers to ensure the value matches Revit's data exactly.
  • Default Values: If the main property has an initializer, the UI will be pre-filled with that value before the provider is triggered.