# MRML node removal callback

**URL:** <https://discourse.slicer.org/t/mrml-node-removal-callback/6514>\
**Category:** Development\
**Tags:** python\
**Created:** [April 16, 2019, 4:30pm UTC](https://discourse.slicer.org/t/mrml-node-removal-callback/6514 "2019-04-16T16:30:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![michalikthomas](https://avatars.discourse-cdn.com/v4/letter/m/7cd45c/32.png) [@michalikthomas](https://discourse.slicer.org/u/michalikthomas)\
**Post date:** [April 16, 2019, 4:30pm UTC](https://discourse.slicer.org/t/mrml-node-removal-callback/6514/1 "2019-04-16T16:30:53Z")

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How to correctly register a callback for MRML node removal (specifically `vtkMRMLModelNode` and `vtkMRMLMarkupsFiducialNode`) in python scripted module?

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [April 16, 2019, 5:03pm UTC](https://discourse.slicer.org/t/mrml-node-removal-callback/6514/2 "2019-04-16T17:03:26Z")

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You can observe [vtkMRMLScene.NodeAboutToBeRemoved](https://apidocs.slicer.org/master/classvtkMRMLScene.html#a8ccb4e378bdb987a4e95ac6cc1067c94a2a51ee0218f53512c95cbc94d5e4dab4) event. See an example how to observe a scene event in the [script repository](https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Show_volume_rendering_automatically_when_a_volume_is_loaded).