' 
' (C) Copyright 2003-2019 by Autodesk, Inc.
' 
' Permission to use, copy, modify, and distribute this software in
' object code form for any purpose and without fee is hereby granted,
' provided that the above copyright notice appears in all copies and
' that both that copyright notice and the limited warranty and
' restricted rights notice below appear in all supporting
' documentation.
'
' AUTODESK PROVIDES THIS PROGRAM "AS IS" AND WITH ALL FAULTS.
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' MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE.  AUTODESK, INC.
' DOES NOT WARRANT THAT THE OPERATION OF THE PROGRAM WILL BE
' UNINTERRUPTED OR ERROR FREE.
' 
' Use, duplication, or disclosure by the U.S. Government is subject to
' restrictions set forth in FAR 52.227-19 (Commercial Computer
' Software - Restricted Rights) and DFAR 252.227-7013(c)(1)(ii)
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'

Option Explicit On
Imports System
Imports Autodesk.Revit.DB

<Autodesk.Revit.Attributes.Transaction(Autodesk.Revit.Attributes.TransactionMode.Manual)> _
<Autodesk.Revit.Attributes.Regeneration(Autodesk.Revit.Attributes.RegenerationOption.Manual)> _
<Autodesk.Revit.Attributes.Journaling(Autodesk.Revit.Attributes.JournalingMode.NoCommandData)> _
Public Class Command2
    Implements Autodesk.Revit.UI.IExternalCommand

    ''' <summary>
    ''' Implement this method as an external command for Revit.
    ''' </summary>
    ''' <param name="commandData">An object that is passed to the external application 
    ''' which contains data related to the command, 
    ''' such as the application object and active view.</param>
    ''' <param name="message">A message that can be set by the external application 
    ''' which will be displayed if a failure or cancellation is returned by 
    ''' the external command.</param>
    ''' <param name="elements">A set of elements to which the external application 
    ''' can add elements that are to be highlighted in case of failure or cancellation.</param>
    ''' <returns>Return the status of the external command. 
    ''' A result of Succeeded means that the API external method functioned as expected. 
    ''' Cancelled can be used to signify that the user cancelled the external operation 
    ''' at some point. Failure should be returned if the application is unable to proceed with 
    ''' the operation.</returns>
    Public Function Execute(ByVal commandData As Autodesk.Revit.UI.ExternalCommandData, ByRef message As String, _
        ByVal elements As Autodesk.Revit.DB.ElementSet) As Autodesk.Revit.UI.Result _
        Implements Autodesk.Revit.UI.IExternalCommand.Execute

        ' Setup a default message in case any exceptions are thrown that we have not
        ' explicitly handled. On failure the message will be displayed by Revit
        message = "The sample failed"
        Execute = Autodesk.Revit.UI.Result.Failed

        Try
            Dim sharedParameterDefinition As Autodesk.Revit.DB.Definition
            sharedParameterDefinition = commandData.Application.Application.OpenSharedParameterFile.Groups. _
                Item("RevitParameters").Definitions.Item("APIParameter")

            Dim mParameterName As String = sharedParameterDefinition.Name
            Dim mNewParamValue As String = "Hello Revit"

            'get a set of element which is not elementType
            Dim filter As Autodesk.Revit.DB.ElementIsElementTypeFilter
            filter = New Autodesk.Revit.DB.ElementIsElementTypeFilter(True)
            Dim collector As Autodesk.Revit.DB.FilteredElementCollector
            collector = New Autodesk.Revit.DB.FilteredElementCollector(commandData.Application.ActiveUIDocument.Document)
            collector.WherePasses(filter)
            Dim iter As IEnumerator
            iter = collector.GetElementIterator

            Dim transaction As Autodesk.Revit.DB.Transaction
            transaction = New Autodesk.Revit.DB.Transaction(commandData.Application.ActiveUIDocument.Document, "SetParameter")
            transaction.Start()
            Do While (iter.MoveNext)
                Dim element As Autodesk.Revit.DB.Element
                element = iter.Current
                If Not (TypeOf element Is Autodesk.Revit.DB.ElementType) Then
                    If Not (element.Category Is Nothing) Then
                        If (element.Category.Name = "Walls") Then

                            Dim param As Autodesk.Revit.DB.Parameter
                            Dim parameters As Autodesk.Revit.DB.ParameterSet = element.Parameters
                            For Each param In parameters
                                If (param.Definition.Name = mParameterName) Then
                                    Try
                                        param.Set(mNewParamValue)
                                    Catch ex As Exception
                                        Continue For
                                    End Try
                                    Exit For
                                End If
                            Next

                        End If
                    End If
                End If
            Loop
            transaction.Commit()

            ' change our result to successful
            Execute = Autodesk.Revit.UI.Result.Succeeded
            Return Execute
        Catch ex As Exception
            message = ex.Message
            Return Execute
        End Try

    End Function
End Class