# Modifying a One2Many field via on\_change

**URL:** <https://discuss.tryton.org/t/modifying-a-one2many-field-via-on-change/3910>\
**Category:** Developer\
**Created:** [March 8, 2021, 7:05am UTC](https://discuss.tryton.org/t/modifying-a-one2many-field-via-on-change/3910 "2021-03-08T07:05:23Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![ced](https://discuss-cdn.tryton.org/user_avatar/discuss.tryton.org/ced/32/1237_2.png) [@ced](https://discuss.tryton.org/u/ced)\
**Post date:** [March 8, 2021, 8:59am UTC](https://discuss.tryton.org/t/modifying-a-one2many-field-via-on-change/3910/4 "2021-03-08T08:59:02Z")

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It is probably a bad idea to modify or create such record with a unique constraint.  
Any way I do not understand why [Setting data for One2Many field trough an on\_change function](https://discuss.tryton.org/t/setting-data-for-one2many-field-trough-an-on-change-function/1592) is not working for you.

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