# updateParameterNodeFromGUI not called when ui is updated because connect() don't work

**URL:** https://discourse.slicer.org/t/updateparameternodefromgui-not-called-when-ui-is-updated-because-connect-dont-work/29778
**Category:** Support
**Created:** [June 1, 2023, 5:45pm UTC](https://discourse.slicer.org/t/updateparameternodefromgui-not-called-when-ui-is-updated-because-connect-dont-work/29778 "2023-06-01T17:45:18Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![tux](https://avatars.discourse-cdn.com/v4/letter/t/f4b2a3/32.png) [@tux](https://discourse.slicer.org/u/tux)
#### Post date: [June 1, 2023, 5:45pm UTC](https://discourse.slicer.org/t/updateparameternodefromgui-not-called-when-ui-is-updated-because-connect-dont-work/29778/1 "2023-06-01T17:45:18Z")

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hi,

I want to create a python module for slicer and i got a problem with the UI.  
When the UI is updated it doesn’t call the updateParameterNodeFromGUI() function and i think it’s because the widget i use isn’t supported by the slicer library.  
I’ve got the line :

self.ui.thresholdFloatInput.connect(“currentNodeChanged(vtkMRMLNode\*)”, self.updateParameterNodeFromGUI)

but there’s this error that show up every time :

PythonQt: QObject::connect() signal ‘currentNodeChanged(vtkMRMLNode\*)’ does not exist on qMRMLSpinBox

I already tried to use different widget (from Qt designer, ctkVTK, ctk and qMRML) but none of them worked.  
I would greatly appreciate any help on what i should use or what i’m misunderstanding here.  
Thanks !

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### Author: ![Sunderlandkyl](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sunderlandkyl/32/79987_2.png) [@Sunderlandkyl](https://discourse.slicer.org/u/Sunderlandkyl)
#### Post date: [June 1, 2023, 5:52pm UTC](https://discourse.slicer.org/t/updateparameternodefromgui-not-called-when-ui-is-updated-because-connect-dont-work/29778/2 "2023-06-01T17:52:55Z")

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For qMRMLSpinBox, you will want to use the “valueChanged(double)” signal.

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<div class="post-metadata">

### Author: ![tux](https://avatars.discourse-cdn.com/v4/letter/t/f4b2a3/32.png) [@tux](https://discourse.slicer.org/u/tux)
#### Post date: [June 2, 2023, 7:05am UTC](https://discourse.slicer.org/t/updateparameternodefromgui-not-called-when-ui-is-updated-because-connect-dont-work/29778/3 "2023-06-02T07:05:44Z")

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It worked perfectly, thank you very much !  
Do you know where i can get the assigned signal of every widget please ?

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<div class="post-metadata">

### Author: ![Sunderlandkyl](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sunderlandkyl/32/79987_2.png) [@Sunderlandkyl](https://discourse.slicer.org/u/Sunderlandkyl)
#### Post date: [June 2, 2023, 2:23pm UTC](https://discourse.slicer.org/t/updateparameternodefromgui-not-called-when-ui-is-updated-because-connect-dont-work/29778/4 "2023-06-02T14:23:20Z")

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The API documentation for Slicer is a good place to start for MRML widgets: [Slicer: qMRMLSpinBox Class Reference](https://apidocs.slicer.org/main/classqMRMLSpinBox.html).

In this case however, despite valueChanged being inherited from ctkDoubleSpinBox it is not documented in in the [member list](https://apidocs.slicer.org/main/classqMRMLSpinBox-members.html).

For CTK widgets I would check the [CTK API documentation](http://www.commontk.org/docs/html/classes.html), though it appears to be down right now.  
For Qt widgets I would check the [Qt API documentation](https://doc.qt.io/qt-5.15/classes.html).

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<div class="post-metadata">

### Author: ![tux](https://avatars.discourse-cdn.com/v4/letter/t/f4b2a3/32.png) [@tux](https://discourse.slicer.org/u/tux)
#### Post date: [June 2, 2023, 3:18pm UTC](https://discourse.slicer.org/t/updateparameternodefromgui-not-called-when-ui-is-updated-because-connect-dont-work/29778/5 "2023-06-02T15:18:24Z")

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I already saw the documentation for MRML widget but i never learned c++ so i was a bit lost and i couldn’t find the signaled associated with the widget, but thank you for the other link !