# Observe GUI table updates in Python

**URL:** <https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430>\
**Category:** Support\
**Created:** [March 26, 2018, 7:50pm UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430 "2018-03-26T19:50:26Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![fuantomu](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@fuantomu](https://discourse.slicer.org/u/fuantomu)\
**Post date:** [March 26, 2018, 7:50pm UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430/1 "2018-03-26T19:50:26Z")

</div>

Hello,  
I’ve searched and tried for several hours now but I can’t seem to figure this out. I use vtkMRMLTableNode for the table and qMRMLTableView for the GUI. How can I add an observer to the table that reacts on adding/modifying values in the cells. The only thing I found is ReferenceModifiedEvent in the vtkMRMLTableViewNode, but I couldn’t get that one to work.  
Also, another question I had regarding tables are column types. I set the type of one of my columns to 1 (which as I understand it is a bool) but I don’t know how to change the cell values in the code now (SetCellText returns errors)

I hope you can understand my problem and thanks in advance for any help!

---

<div class="post-metadata">

**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:** [March 26, 2018, 9:22pm UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430/2 "2018-03-26T21:22:51Z")

</div>

What you described should work. Could you send a link to your source code?

---

<div class="post-metadata">

**Author:** ![fuantomu](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@fuantomu](https://discourse.slicer.org/u/fuantomu)\
**Post date:** [March 26, 2018, 10:13pm UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430/3 "2018-03-26T22:13:37Z")

</div>

[https://pastebin.com/raw/pXRf2aVD](https://pastebin.com/raw/pXRf2aVD)

This is the code I use for the table

---

<div class="post-metadata">

**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:** [March 27, 2018, 12:43am UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430/4 "2018-03-27T00:43:55Z")

</div>

It seems that you try to create a point list widget. There is already such widget, with lots of features and configuration options: [qSlicerSimpleMarkupsWidget](http://apidocs.slicer.org/master/classqSlicerSimpleMarkupsWidget.html).

```
# Create a markup fiducial list
fidNode=slicer.mrmlScene.AddNewNodeByClass("vtkMRMLMarkupsFiducialNode")
fidNode.CreateDefaultDisplayNodes()
fidNode.AddFiducial(35,10,12)
fidNode.AddFiducial(15,0,5)
fidNode.AddFiducial(0,0,3)
# Create a list widget
fidListWidget=slicer.qSlicerSimpleMarkupsWidget()
fidListWidget.setMRMLScene(slicer.mrmlScene)
fidListWidget.jumpToSliceEnabled = True
fidListWidget.setCurrentNode(fidNode)
fidListWidget.show()

```

In your code the main issue was the you’ve observed the wrong event. This will work:

```
# Create table node
tableNode = slicer.mrmlScene.AddNewNodeByClass("vtkMRMLTableNode")
col=tableNode.AddColumn()
col.SetName('Name')
col=tableNode.AddColumn()
col.SetName('Visible')
col=tableNode.AddColumn(vtk.vtkFloatArray())
col.SetName('Number')
tableNode.SetColumnType('Visible',vtk.VTK_BIT)
tableNode.AddEmptyRow()
tableNode.AddEmptyRow()
tableNode.AddEmptyRow()
tableNode.SetCellText(1,0,"ok")
tableNode.SetCellText(1,1,"1")

# Table view
tableView=slicer.qMRMLTableView()
tableView.setMRMLScene(slicer.mrmlScene)
tableView.setMRMLTableNode(tableNode)
tableView.show()

# Observe modifications

def tableModified(caller, event):
  print("Table modified")

observerTag = tableNode.AddObserver(vtk.vtkCommand.ModifiedEvent, tableModified)
```

---

<div class="post-metadata">

**Author:** ![fuantomu](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@fuantomu](https://discourse.slicer.org/u/fuantomu)\
**Post date:** [March 27, 2018, 12:09pm UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430/5 "2018-03-27T12:09:44Z")

</div>

Oh wow, I didn’t know there was something like that already. Thanks a lot! I will probably implement it later but for now I’ll try to get a better understanding first.  
On a side node: Is it possible to get the row id that was modified via calldata or a similar function to slicer.clickedMarkupIndex? vtk.VTK\_INT seems to crash slicer when calling the tableModified function.

---

<div class="post-metadata">

**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:** [March 27, 2018, 1:04pm UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430/6 "2018-03-27T13:04:21Z")

</div>

> [@fuantomu](#):
>
> Is it possible to get the row id that was modified

See these examples:

[https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Get\_a\_notification\_if\_a\_markup\_point\_position\_is\_modified](https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Get_a_notification_if_a_markup_point_position_is_modified)

[https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Manipulating\_objects\_in\_the\_slice\_viewer](https://www.slicer.org/wiki/Documentation/Nightly/ScriptRepository#Manipulating_objects_in_the_slice_viewer)

---

<div class="post-metadata">

**Author:** ![fuantomu](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@fuantomu](https://discourse.slicer.org/u/fuantomu)\
**Post date:** [March 27, 2018, 5:14pm UTC](https://discourse.slicer.org/t/observe-gui-table-updates-in-python/2430/7 "2018-03-27T17:14:51Z")

</div>

Thank you very much - I ended up using the widget you suggested and everything is working fine now 🙂