Second call to BOMQuantity.GetBaseQuantity unhandled exception

[prussellZXB3F]

I'm on Inventor 2019.4.1 using ilogic trying to get the BOM quantity/length, I can get the length of the first item but after that any call to BOMQuantity.GetBaseQuantity() fails.

Is this a known bug?

Cut and paste code if you want to test

Dim doc As AssemblyDocument
If ThisApplication.ActiveDocumentType = Inventor.DocumentTypeEnum.kAssemblyDocumentObject Then
	doc = ThisApplication.ActiveDocument
Else
	MessageBox.Show("You've got to have an assembly as the active document to run the tool")
	Exit Sub
End If

Dim allParts As ComponentOccurrencesEnumerator
allParts = doc.ComponentDefinition.Occurrences.AllLeafOccurrences

For Each part As ComponentOccurrence In allParts
	If part.Definition.BOMQuantity.BaseUnits = "m" Or part.Definition.BOMQuantity.BaseUnits = "mm" Then
		MessageBox.Show(part.Name)
		MessageBox.Show(part.Definition.BOMQuantity.BaseUnits)
		Dim val As Inventor.Parameter
		Dim type As BOMQuantityTypeEnum
		part.Definition.BOMQuantity.GetBaseQuantity(type, val)
		MessageBox.Show(val.Value)
	End If
Next

[WCrihfield]

Hi @prussellZXB3F.  You may need to check the returned value of the variable "type", before trying to use the variable "val", because if "type" is not based on a parameter (like 'Each'), it won't return a parameter, therefore "val" is still Nothing, and you are trying to show its value in a message box when the variable's value hasn't been set yet.  Check out the online help page for the method (BOMQuantity.GetBaseQuantity()).

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[prussellZXB3F]

Cheers for taking a look WCrihfield.

I don't thing that is the issue as I'm checking for base unit is either mm or m before trying to pull the parameter.

Also I through testing I'm pretty sure it only works on the first component it hits.

I've got several CC parts in an assembly that have length property as their BOM qty. I got the error but couldn't see any difference between the part it worked on and those it didn't. I then deleted the component that worked from the assembly and now the part that followed and was failing now works, everything after it still fails?!

[WCrihfield · Accepted solution]

Next I'm thinking that maybe one or both of the variables 'val' &/or 'type' may not be getting cleared before/after each loop.  I know it doesn't seem right, since they are being created within the loop, but I have seen stuff like that happen before.  So maybe try setting initial nullifying values to them just to be sure.

Something like this maybe:

Dim val As Inventor.Parameter = Nothing
Dim type As BOMQuantityTypeEnum = 0

Nullifying an Enum variable can be a bit tricky, because they often can have two types of acceptable values (Integer or Enum variation).  In this case the 'BOMQuantityTypeEnum' only has two possible values/variations, and neither of them have a value of zero (0), so this should work.

[prussellZXB3F]

Declaring the parameter and expressly setting to nothing fixed it 🙂

This somewhat undermines some of what I thought I knew about programming but happy with the fix.