Tutorial 4: Element Selection

Learn how to let the user "Pick" elements from the model, using Paracore's Strongly Typed Selection to safely get exactly what you need.

Finished Script: 03_Tutorials/Paracore_Fundamentals/04_ElementSelection.cs

🎯 What You'll Learn

• The [Select] attribute
• Strongly Typed Selection: Asking for a Wall instead of a generic ID
• Modifying element parameters

Step 1: Define Inputs (The Smart Way)

In the past, you had to ask for a generic Reference or long (Element ID) and then manually find the object. With Paracore Hydration, you just ask for the type you want.

public class Params
{
    /// <summary>Select a Wall in Revit</summary>
    [Select(SelectionType.Element)]
    [Mandatory]
    public Wall TargetWall { get; set; }
    
    /// <summary>New comment text</summary>
    public string Comment { get; set; } = "Updated by Paracore";
}

Notice public Wall TargetWall. Paracore sees this and:

1. Gives the user a "Pick" button.
2. Filters the selection so they can only pick a wall.
3. Returns the actual Wall object to your script.

Step 2: Validate the Selection

Even though Paracore filters selection, the user might cancel or something might go wrong. Always check for null.

var p = new Params();

if (p.TargetWall == null)
{
    Println("🚫 No wall selected.");
    return;
}

Note: We don't need Doc.GetElement(id). We already have p.TargetWall!

Step 3: Modify the Element

Let's update the comments on the selected wall.

Transact("Update Wall Comment", () => {
    // Modify the real Wall object directly
    var param = p.TargetWall.get_Parameter(BuiltInParameter.ALL_MODEL_INSTANCE_COMMENTS);
    param?.Set(p.Comment);
    
    Println($"✅ Updated Wall {p.TargetWall.Id} with comment: {p.Comment}");
});

Step 4: Run and Verify

1. Click the "Pick" button next to TargetWall.
2. The Paracore window will minimize.
3. Try to pick a Floor or Window -> Revit won't let you!
4. Pick a Wall.
5. Enter a comment and click Run Script.
6. Select the wall in Revit and check its properties.

💡 Try This

1. Change public Wall to public Window and see how the selection filter changes.
2. Use [Select(SelectionType.Point)] with public XYZ Point to pick a location in 3D space.

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Next: Tutorial 5: Multi-File Scripts →