Error HRESULT E_FAIL in combination with GetVar

SOLIDWORKS API/VBA Macros
1

Hello everyone,
can someone help me understand the problem to the following situation:
I have written a little test addin for Solidworks PDM.
First of all the code:
This is my Main.cs:

using EPDM.Interop.epdm;
using System;
using System.Runtime.InteropServices;

namespace MyTestAddin
{
    [ComVisible(true)]
    [Guid("11589DD0-43DC-4D67-B1EF-670680472D77")]
    public class Main : IEdmAddIn5
    {
        public void GetAddInInfo(ref EdmAddInInfo poInfo, IEdmVault5 poVault, IEdmCmdMgr5 poCmdMgr)
        {
            poInfo.mbsAddInName = "Test Addin";
            poInfo.mlAddInVersion = 1;
            poInfo.mlRequiredVersionMajor = 28;

            poCmdMgr.AddHook(EdmCmdType.EdmCmd_CardButton);
        }

        public void OnCmd(ref EdmCmd poCmd, ref EdmCmdData[] ppoData)
        {
            switch (poCmd.meCmdType)
            {
                case EdmCmdType.EdmCmd_CardButton:
                    string addInTagName = poCmd.mbsComment;
                    if (addInTagName == "MyTestButton")
                    {
                        var enumVar = poCmd.mpoExtra as IEdmEnumeratorVariable5;
                        object varVal;
                        enumVar.GetVar("SL_BENENNUNG","@", out varVal);
                        var retVal = varVal?.ToString();
                        ((EdmVault5)(poCmd.mpoVault)).MsgBox(poCmd.mlParentWnd, "Call from OnCmd: " + retVal);

                        Form1 form1 = new Form1(ref poCmd);
                        form1.Show();
                    }
                    break;
            }
        }
    }
}

This is my Form1.cs:

using EPDM.Interop.epdm;
using System;
using System.Windows.Forms;

namespace MyTestAddin
{
    public partial class Form1 : Form
    {
        private EdmCmd _poCmd;
        public Form1(ref EdmCmd poCmd)
        {
            InitializeComponent();
            var enumVar = poCmd.mpoExtra as IEdmEnumeratorVariable5;
            object varVal;
            enumVar.GetVar("SL_BENENNUNG", "@", out varVal);
            var retVal = varVal?.ToString();
            ((EdmVault5)(poCmd.mpoVault)).MsgBox(poCmd.mlParentWnd, "Call from Form1 constructor: " + retVal);

            _poCmd = poCmd;
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            var enumVar = _poCmd.mpoExtra as IEdmEnumeratorVariable5;
            object varVal;
            enumVar.GetVar("SL_BENENNUNG", "@", out varVal);
            var retVal = varVal?.ToString();
            ((EdmVault5)(_poCmd.mpoVault)).MsgBox(_poCmd.mlParentWnd, "Call from button1_Click: " + retVal);
        }
    }
}

Now the following happens:
when i press the button in my datacard, a message box opens with the text: Call from OnCmd: Test
The word Test comes from the variable. So this is exactly what I was expacting.
The next thing that happens is a message box opens with the text: Call from Form1 constructor: Test
Again this is exactly what I was expacting.
Now the Form1 is open and I click on the button. The button2_Click Event is raised and I get an error on this line:

enumVar.GetVar("SL_BENENNUNG", "@", out varVal);

The error is: Error HRESULT E_FAIL has been returned from a call to a COM component
Can anyone please explain this to me? What did I do wrong?

2

Thank you for posting and welcome to cadoverflow!

I see so many things wrong with this code. I’d pass the vault object and the file and folder id instead of the EdmEnumeratorVariable5 and work with that in the form.

It is possible that reference to the enumerator variable is no longer valid. Funky stuff cards.

If you are hell-bent on getting this fixed, please create a public repo with a MVP so we can replicate your issue.