# Is there any "CanFilter" APIs?

**URL:** https://discourse.paraview.org/t/is-there-any-canfilter-apis/2222
**Category:** Development
**Created:** [July 15, 2019, 3:44pm UTC](https://discourse.paraview.org/t/is-there-any-canfilter-apis/2222 "2019-07-15T15:44:31Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [July 15, 2019, 3:44pm UTC](https://discourse.paraview.org/t/is-there-any-canfilter-apis/2222/1 "2019-07-15T15:44:31Z")

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I create my own filter, but these filter is just can use for my own “MyMultiBlockDataSet” which inherited from vtkMultiBlockDataSet.

So i wonder is there any method i can check the input vtkMultiBlockDataSet to decide whether i can filter it or not ?

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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: [July 15, 2019, 3:56pm UTC](https://discourse.paraview.org/t/is-there-any-canfilter-apis/2222/2 "2019-07-15T15:56:34Z")

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in the xml declaration of your filter you can check a number of things, eg: the presence of a three component point data array.

Is that what you are looking for ?

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### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [July 15, 2019, 3:59pm UTC](https://discourse.paraview.org/t/is-there-any-canfilter-apis/2222/3 "2019-07-15T15:59:54Z")

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I want a method like “CanFilter(inputDataObject)”, then i can cast this “inputDataObject” to “myOwnDataObject”, if it is successful, it means myFilter can handle…

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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: [July 15, 2019, 4:01pm UTC](https://discourse.paraview.org/t/is-there-any-canfilter-apis/2222/4 "2019-07-15T16:01:13Z")

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Not possible without more complex implementation. I suggested an alternative.

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### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [July 15, 2019, 4:02pm UTC](https://discourse.paraview.org/t/is-there-any-canfilter-apis/2222/5 "2019-07-15T16:02:40Z")

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OK, Thank you for your suggestion.

If this is not so directly, i will give up…