Calling save() on InventoryItem without changes produces unnecessary changelog entry #4998

New Issue

adam · 2025-12-29T19:23:01+01:00

adam commented

2025-12-29 19:23:01 +01:00

Originally created by @bluecmd on GitHub (Jun 12, 2021).

NetBox version

v2.11.6

Python version

3.7

Steps to Reproduce

Call save() on an InventoryItem via Netbox Script:

it = InventoryItem.objects.all()[0]
it.save()

Check changelog of the object
The changelog only shows "Post-Change Data" and an empty "Pre-Change Data"

If I call .snapshot() before the "Pre-Change Data" is populated, and the UI shows "No difference".

Expected Behavior

Either mentioning that .snapshot() is important for Netbox Scripts on the https://netbox.readthedocs.io/en/stable/additional-features/custom-scripts/ website, or make it automatic, would be appreciated
That .save() with no changes is silent/ignored.

Observed Behavior

An moot changelog entry is created.

Originally created by @bluecmd on GitHub (Jun 12, 2021). ### NetBox version v2.11.6 ### Python version 3.7 ### Steps to Reproduce 1. Call `save()` on an InventoryItem via Netbox Script: ```python3 it = InventoryItem.objects.all()[0] it.save() ``` 2. Check changelog of the object 3. The changelog only shows "Post-Change Data" and an empty "Pre-Change Data" If I call `.snapshot()` before the "Pre-Change Data" is populated, and the UI shows "No difference". ### Expected Behavior - Either mentioning that `.snapshot()` is important for Netbox Scripts on the https://netbox.readthedocs.io/en/stable/additional-features/custom-scripts/ website, or make it automatic, would be appreciated - That `.save()` with no changes is silent/ignored. ### Observed Behavior An moot changelog entry is created.

adam closed this issue

2025-12-29 19:23:01 +01:00

adam commented

2025-12-29 19:23:01 +01:00

@bluecmd commented on GitHub (Jun 12, 2021):

For now I have worked around this in my scripts by doing this:

-                iitem.part_id = psu['name']
-                iitem.serial = psu['serialNum']
-                iitem.discovered = True
-                iitem.save()
+                if iitem.part_id != psu['name'] or iitem.serial != psu['serialNum'] or not iitem.discovered:
+                    iitem.snapshot()
+                    iitem.part_id = psu['name']
+                    iitem.serial = psu['serialNum']
+                    iitem.discovered = True
+                    iitem.save()

If this is the intended way going forward I am OK with updating my scripts accordingly but ask that e.g. the example Custom Script is updated with this information on how to best do changes.

@bluecmd commented on GitHub (Jun 12, 2021): For now I have worked around this in my scripts by doing this: ```diff - iitem.part_id = psu['name'] - iitem.serial = psu['serialNum'] - iitem.discovered = True - iitem.save() + if iitem.part_id != psu['name'] or iitem.serial != psu['serialNum'] or not iitem.discovered: + iitem.snapshot() + iitem.part_id = psu['name'] + iitem.serial = psu['serialNum'] + iitem.discovered = True + iitem.save() ``` If this is the intended way going forward I am OK with updating my scripts accordingly but ask that e.g. the example Custom Script is updated with this information on how to best do changes.

adam commented

2025-12-29 19:23:02 +01:00

@jeremystretch commented on GitHub (Jun 14, 2021):

This intended behavior. Even when no data is being modified, there may still be a desire to record that a save event took place.

@jeremystretch commented on GitHub (Jun 14, 2021): This intended behavior. Even when no data is being modified, there may still be a desire to record that a save event took place.

adam commented

2025-12-29 19:23:02 +01:00

@bluecmd commented on GitHub (Jun 14, 2021):

Ok thanks for confirming.

I would suggest adding a section to https://netbox.readthedocs.io/en/stable/additional-features/custom-scripts/ describing the semantics around save() and snapshot(). It was quite hard going down the rabbit hole of Django data models and how things are supposed to work together, so that might be useful for people.

@bluecmd commented on GitHub (Jun 14, 2021): Ok thanks for confirming. I would suggest adding a section to https://netbox.readthedocs.io/en/stable/additional-features/custom-scripts/ describing the semantics around save() and snapshot(). It was quite hard going down the rabbit hole of Django data models and how things are supposed to work together, so that might be useful for people.

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Reference: starred/netbox#4998