How to make Dyanmo software package (3) - drop-down box control

The node of the Dynamo software package is relatively easy, but the drop-down box is more troublesome, and the interface DSDropDownBase needs to be implemented here.

First look at the effect:

Paste the source code directly here:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using CoreNodeModels;
using Dynamo.Graph.Nodes;
using Newtonsoft.Json;
using ProtoCore.AST.AssociativeAST;
using RevitServices.Persistence;
using Autodesk.Revit.DB.Structure;
using Autodesk.Revit.DB;
using RenGeDynamo.Filter;

namespace RenGeDynamo.Rebar
{
    [NodeName("Rebar BarType Name")]
    [NodeDescription("Input reinforcement type, output reinforcement type name")]
    [IsDesignScriptCompatible]
    public class RebarBarTypeName : DSDropDownBase
    {
        public RebarBarTypeName() : base("rebarBarType") { }
        
        [JsonConstructor]
        public RebarBarTypeName(IEnumerable<PortModel> inPorts, IEnumerable<PortModel> outPorts) : base("rebarBarType", inPorts, outPorts) { }

        protected override SelectionState PopulateItemsCore(string currentSelection)
        {           
            Items.Clear();            
            foreach(var rebarTypeElement in GetRebarType())
            {               
                Items.Add(new DynamoDropDownItem(rebarTypeElement.Name, rebarTypeElement.Name));                 
            }           

            SelectedIndex = 0;
            return SelectionState.Done;
        }

        public override IEnumerable<AssociativeNode> BuildOutputAst(List<AssociativeNode> inputAstNodes)
        {
            // Build an AST node for the type of object contained in your Items collection.            
            var intNode = AstFactory.BuildPrimitiveNodeFromObject(Items[SelectedIndex].Item);
            var assign = AstFactory.BuildAssignment (GetAstIdentifierForOutputIndex (0), intNode);
            return new List<AssociativeNode> { assign };
        }

        private List<Element> GetRebarType()
        {
            Document doc = DocumentManager.Instance.CurrentDBDocument;
            RebarFilter filter = new RebarFilter();
            return filter.FilterRebarBarType(doc).ToList();
        }
    }
}

The above code uses a filter, but this filter needs to use Revit documents. It is very easy to obtain Revit documents in Dynamo, just use Document doc = DocumentManager.Instance.CurrentDBDocument.

Filtering is simpler, the same as Revit secondary development.

public class RebarFilter
    {
        public  FilteredElementCollector FilterRebarBarType(Document doc)
        {
            FilteredElementCollector fliteredElements = new FilteredElementCollector(doc);
            ElementClassFilter classFilter = new ElementClassFilter(typeof(RebarBarType));
            fliteredElements = fliteredElements.WherePasses(classFilter);
            return fliteredElements;
        }

        public FilteredElementCollector FilterRebarShape(Document doc)
        {
            FilteredElementCollector fliteredElements = new FilteredElementCollector(doc);
            ElementClassFilter classFilter = new ElementClassFilter(typeof(RebarShape));
            fliteredElements = fliteredElements.WherePasses(classFilter);
            return fliteredElements;
        }
    }

What is more troublesome is that there are many dll files that need to be referenced to make this control. As shown below:

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