# Auto fill content fields when saving a content

**URL:** <https://community.bloomreach.com/t/auto-fill-content-fields-when-saving-a-content/2417>\
**Category:** Experience Manager (PaaS/OnPrem)\
**Created:** [February 23, 2021, 9:38am UTC](https://community.bloomreach.com/t/auto-fill-content-fields-when-saving-a-content/2417 "2021-02-23T09:38:12Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![asanchez](https://avatars.discourse-cdn.com/v4/letter/a/46a35a/32.png) [@asanchez](https://community.bloomreach.com/u/asanchez)\
**Post date:** [February 23, 2021, 9:38am UTC](https://community.bloomreach.com/t/auto-fill-content-fields-when-saving-a-content/2417/1 "2021-02-23T09:38:12Z")

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Hello,

I have the next requirement and I not finding any clean way in the documentation to implement it.

Basically, we need a new field (C) which value must be filled with the content of another two fields (A and B) under the criteria of taking A if is not empty or B otherwise.  
The field C will be hidden so the editor can’t tamper with it.

There is something similar to a custom interceptor class that would allow me to change the value after the customer save the content?

So far, I think I could use a custom validator or using javascript but I don’t know yet if are viable.

Thanks for your help in advance

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**Author:** ![jasper.floor](https://yyz1.discourse-cdn.com/flex027/user_avatar/community.bloomreach.com/jasper.floor/32/28_2.png) [@jasper.floor](https://community.bloomreach.com/u/jasper.floor)\
**Post date:** [February 23, 2021, 10:23am UTC](https://community.bloomreach.com/t/auto-fill-content-fields-when-saving-a-content/2417/2 "2021-02-23T10:23:02Z")

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This sounds like a job for:

> **[Derived Data - Bloomreach Experience - Open Source CMS](https://documentation.bloomreach.com/14/library/concepts/content-repository/derived-data.html)**
>
> Open Source Enterprise Content Management

To not show the field just make sure it isn’t referenced in the namespace editor:templates definition.

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**Author:** ![asanchez](https://avatars.discourse-cdn.com/v4/letter/a/46a35a/32.png) [@asanchez](https://community.bloomreach.com/u/asanchez)\
**Post date:** [February 23, 2021, 10:26am UTC](https://community.bloomreach.com/t/auto-fill-content-fields-when-saving-a-content/2417/3 "2021-02-23T10:26:39Z")

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Thanks! we are going to give it a try right now.