# Extending existing FieldTypes/Fields functionality?

**URL:** <https://forum.litium.com/t/extending-existing-fieldtypes-fields-functionality/161>\
**Category:** Questions\
**Created:** [July 6, 2018, 9:04am UTC](https://forum.litium.com/t/extending-existing-fieldtypes-fields-functionality/161 "2018-07-06T09:04:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Zsrdos](https://avatars.discourse-cdn.com/v4/letter/z/74df32/32.png) [@Zsrdos](https://forum.litium.com/u/Zsrdos)\
**Post date:** [July 6, 2018, 9:04am UTC](https://forum.litium.com/t/extending-existing-fieldtypes-fields-functionality/161/1 "2018-07-06T09:04:47Z")

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Hi, is it possible to extend or listening for a field type save/update action? Let’s say I have a Field of type TextOption names Size.

When I add the size XXXL to this list, is it possible to be listening, or implement a callback that can take this information and manipulate it or take an action? Let’s say I want to transform the option to lower case before saving or send the option of to an external system after saving is complete etc.

Litium version: 6.2

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<div class="post-metadata">

**Author:** ![marten](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.litium.com/marten/32/11_2.png) [@marten](https://forum.litium.com/u/marten)\
**Post date:** [July 6, 2018, 9:20am UTC](https://forum.litium.com/t/extending-existing-fieldtypes-fields-functionality/161/2 "2018-07-06T09:20:15Z")

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Try using [https://docs.litium.com/documentation/architecture/events-handling](https://docs.litium.com/documentation/architecture/events-handling) with the events:

```auto
Products.Events.FieldDefinitionUpdated
Products.Events.FieldDefinitionCreated

```

Unfortunately it is currently not possible to see what data is changed on an entity in its update-event.

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<div class="post-metadata">

**Author:** ![Zsrdos](https://avatars.discourse-cdn.com/v4/letter/z/74df32/32.png) [@Zsrdos](https://forum.litium.com/u/Zsrdos)\
**Post date:** [July 6, 2018, 9:31am UTC](https://forum.litium.com/t/extending-existing-fieldtypes-fields-functionality/161/3 "2018-07-06T09:31:12Z")

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Can this be done if I create new custom FieldType? Or will all field have this limitation?  
So for now, to manage the example task I need to subscribe to Products.Events.FieldDefinitionUpdated and loop over all the options and updating em or sending all option over for syncing?

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<div class="post-metadata">

**Author:** ![marten](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.litium.com/marten/32/11_2.png) [@marten](https://forum.litium.com/u/marten)\
**Post date:** [July 6, 2018, 10:16am UTC](https://forum.litium.com/t/extending-existing-fieldtypes-fields-functionality/161/4 "2018-07-06T10:16:54Z")

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Custom fieldtypes work the same way as standard in this case.

And yes, you will need to sync the full list on every update since you cannot see which option has been modified.