# previousValue from change Scripts Issue **URL:** \ **Category:** Ignition\ **Tags:** perspective\ **Created:** [October 24, 2024, 8:53pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755 "2024-10-24T20:53:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Matthew\_Breeding](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@Matthew\_Breeding](https://forum.inductiveautomation.com/u/Matthew_Breeding)\ **Post date:** [October 24, 2024, 8:53pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/1 "2024-10-24T20:53:06Z")
so I am trying to pull the previous value from a change script but I unable to use the methods or properties associated with QualifiedValues datatype I can see if I: `prevV = previousValue system.perspective.print(prevV)` it returns `QV[[Lcom.inductiveautomation.ignition.common.model.values.QualifiedValue;@5db0174b, Good, Thu Oct 24 12:49:52 EDT 2024] ` But if i try to reference or use any of the qualified values methods it gives me this `AttributeError("'NoneType' object has no attribute 'getValue'",) ` This is the code that throws the error ` prevV = previousValue.getValue() system.perspective.print(prevV)` any ideas on why this would be happening? ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [October 24, 2024, 8:54pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/2 "2024-10-24T20:54:47Z")
Are you checking the `initialChange` flag? There's no previous value at all when that flag is true. ---
**Author:** ![Matthew\_Breeding](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@Matthew\_Breeding](https://forum.inductiveautomation.com/u/Matthew_Breeding)\ **Post date:** [October 24, 2024, 9:09pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/3 "2024-10-24T21:09:16Z")
Are these available when you are doing a change script on a component? I have a change script on an array of objects, sorry should have clarified earlier I know they are available on tag changes, but I cannot see/find where you pass the flag for component property change scripts. ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [October 24, 2024, 9:27pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/4 "2024-10-24T21:27:18Z")
Interesting. I hadn't noticed that there's no `initialChange` flag. But `previousValue` being null on first change makes sense. You should check for that: ```python if previousValue is None: # handle first update else: # handle change ``` ---
**Author:** ![Matthew\_Breeding](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@Matthew\_Breeding](https://forum.inductiveautomation.com/u/Matthew_Breeding)\ **Post date:** [October 24, 2024, 9:32pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/5 "2024-10-24T21:32:36Z")
Okay that makes sense, I have a property that is binded to a sql query and data being pulled is _default_ data in my databse so it should never be null. After testing aswell your theory was correct, on the first change i get the error but the second change it returns the data. should I have this configured differently for my use case? ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [October 24, 2024, 9:35pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/6 "2024-10-24T21:35:58Z")
> [@Matthew\_Breeding](#): > > for my use case? You haven't explained your use-case, so I don't know. ---
**Author:** ![Matthew\_Breeding](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@Matthew\_Breeding](https://forum.inductiveautomation.com/u/Matthew_Breeding)\ **Post date:** [October 24, 2024, 9:40pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/7 "2024-10-24T21:40:18Z")
oh sorry, so I have a tables components that renders data depending what on what data is being passed, I also want the option for the user to change the data via change script. So I use an embedded view and referenced my table component. The data param for the embedded view I bind to an sql query(this is also where the change script is) so the data will theoretically never be null initially ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [October 24, 2024, 9:42pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/8 "2024-10-24T21:42:26Z")
I would make the property non-persistent so it always does start with a null. ---
**Author:** ![Matthew\_Breeding](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@Matthew\_Breeding](https://forum.inductiveautomation.com/u/Matthew_Breeding)\ **Post date:** [October 24, 2024, 9:43pm UTC](https://forum.inductiveautomation.com/t/previousvalue-from-change-scripts-issue/97755/9 "2024-10-24T21:43:32Z")
Okay I will try that, thank you for the suggestion