# Call filter multiple times after changes on slider property

**URL:** https://discourse.paraview.org/t/call-filter-multiple-times-after-changes-on-slider-property/4982
**Category:** Development
**Created:** [July 29, 2020, 12:03pm UTC](https://discourse.paraview.org/t/call-filter-multiple-times-after-changes-on-slider-property/4982 "2020-07-29T12:03:18Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![Alberto](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/a/ea5d25/32.png) [@Alberto](https://discourse.paraview.org/u/Alberto)
#### Post date: [July 29, 2020, 12:03pm UTC](https://discourse.paraview.org/t/call-filter-multiple-times-after-changes-on-slider-property/4982/1 "2020-07-29T12:03:18Z")

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I compiled a filter which works with a slider value and a Python script.  
The first time I run the filter it works fine.  
Then, if I change the value of slider and do “Apply” the filter doesn’t work anymore; the Python script is executed but the Pipeline doesn’t update.  
How can I update the pipelines sources that depends from the filter?

Thank you in advance

Alberto

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [August 4, 2020, 2:42pm UTC](https://discourse.paraview.org/t/call-filter-multiple-times-after-changes-on-slider-property/4982/2 "2020-08-04T14:42:17Z")

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Please share the source of your filter.

You probably forgot to call `this->Modified()` in your setter, or use `vtkSetMacro` instead.

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### Author: ![Alberto](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/a/ea5d25/32.png) [@Alberto](https://discourse.paraview.org/u/Alberto)
#### Post date: [August 5, 2020, 8:46am UTC](https://discourse.paraview.org/t/call-filter-multiple-times-after-changes-on-slider-property/4982/3 "2020-08-05T08:46:48Z")

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The filter is a Python programmable filter with an xml file compiled into a dll  
Where should I insert the Modified() condition?

Thank you

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### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [August 6, 2020, 6:45am UTC](https://discourse.paraview.org/t/call-filter-multiple-times-after-changes-on-slider-property/4982/4 "2020-08-06T06:45:28Z")

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Please share your code.

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### Author: ![Alberto](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/a/ea5d25/32.png) [@Alberto](https://discourse.paraview.org/u/Alberto)
#### Post date: [August 6, 2020, 7:24am UTC](https://discourse.paraview.org/t/call-filter-multiple-times-after-changes-on-slider-property/4982/5 "2020-08-06T07:24:10Z")

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I solved it.

Thank you