Problem Description

How can we set a new property value to a set of selected nodes based on a given criteria?
In this wiki, the above requirement will be achieved with a sample problem related to selection of point nodes. We are going to select all the point nodes with X coordinates value equals to 100 and modify the part values of these selected point nodes.

Solution

The selection of nodes can be done with function Nodes(). This library function returns a list of all nodes or the nodes that fulfill the given criteria. Below are some examples of how the function works

Get all nodes:
Nodes()

Get all Line nodes:
Nodes(n=> n is Line)

Get all nodes whose names start with "bspline":
Nodes(n => n .Name.StartsWith('bspline')

Get all nodes that have less than 5 vertices:
Nodes(n => n is polygon && n.vertices.Count <5)

To set the property of the selected nodes, we need to use the function SetPropertyValue(). This function sets a value to the mentioned property of the object. Below is one example of how it works.

Set value 1 to the property LineWeight of the node line01
SetPropertyValue(line01, 'LineWeight', 1)
Note: the property name always needs to put in string format i.e quoted.

With combination of the above functions and GC scripting, we can write a small function inside the FunctionCall node to achieve as mentioned in the problem description.

function ( )
{
    Node[] a = Nodes(n=> n is Point && n.X ==100);   // Select all point nodes those have X coordinate value equals to 100
    foreach( PointNode in a) 
    {
     SetPropertyValue(PointNode, 'Part', {'Grids','Bubbles'});   //set property 'Part' equals to value {'Grids','Bubbles'}
    }
    
    return a;

}

Update Model after the function is applied.

Please go through the sample file Selection of Nodes and set property value.gct.