# Trying to use the vtkInformation/vtkInformationKey system for own purposes

**URL:** https://discourse.paraview.org/t/trying-to-use-the-vtkinformation-vtkinformationkey-system-for-own-purposes/10568
**Category:** Development
**Created:** [October 21, 2022, 3:24pm UTC](https://discourse.paraview.org/t/trying-to-use-the-vtkinformation-vtkinformationkey-system-for-own-purposes/10568 "2022-10-21T15:24:41Z")
**Posts on this page:** 1
**Showing post:** 2

<div class="post-metadata">

### 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: [October 24, 2022, 2:41am UTC](https://discourse.paraview.org/t/trying-to-use-the-vtkinformation-vtkinformationkey-system-for-own-purposes/10568/2 "2022-10-24T02:41:06Z")

</div>

Hi @cobo

1. Info down pipeline

To transfer information for a filter **to the next** filter,use the “KEYS\_TO\_COPY” information key:

> [@Set size of StringVectorProperty list at loading of state file](https://discourse.paraview.org/t/set-size-of-stringvectorproperty-list-at-loading-of-state-file/845):
>
> Hello, I’ve been working on a ParaView plugin very recently. In the XML definition, I used the following widget: \<StringVectorProperty name="ParameterNames" command="SetParameterNames" clean\_command="ResetParameterNamesToDefault" information\_property="ParameterNameInfo" number\_of\_elements\_per\_command="1" repeat\_command="1" use\_index="1" …

It will not go through the whole pipeline though.

It is possible to have keys copy themselves over and over but you need to create your own key class implementing `CopyDefaultInformation` (or use a existing one like `vtkInformationDataObjectMetaDataKey`)

1. Info from server to client

Use Information Properties to send information from the server to the client. You can take a look at `Examples/Plugins/PropertyWidgets/Plugin/PropertyWidgetsFilter.xml` and it’s `information_only` property.

---

_[View the full topic](https://discourse.paraview.org/t/trying-to-use-the-vtkinformation-vtkinformationkey-system-for-own-purposes/10568)._