# Prevent certain inputs, like "user at gmail com"

**URL:** <https://www.ruby-forum.com/t/prevent-certain-inputs-like-user-at-gmail-com/181232>\
**Category:** Rails\
**Created:** [January 7, 2010, 7:35pm UTC](https://www.ruby-forum.com/t/prevent-certain-inputs-like-user-at-gmail-com/181232 "2010-01-07T19:35:28Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![tomtt](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/e47c2d/32.png) [@tomtt](https://www.ruby-forum.com/u/tomtt)\
**Post date:** [January 7, 2010, 7:35pm UTC](https://www.ruby-forum.com/t/prevent-certain-inputs-like-user-at-gmail-com/181232/1 "2010-01-07T19:35:28Z")

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hi,

i have a"comment" field in my app which is kinda public, but i still  
want to have certain control over of what a user can enter and what  
not: eg not allowed are

- email addresses
- fake string like: “user at gmail com”
- …
- …

is there anything out there or am i better of using writing my own  
“validations”

thx tom

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<div class="post-metadata">

**Author:** ![tomtt](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/e47c2d/32.png) [@tomtt](https://www.ruby-forum.com/u/tomtt)\
**Post date:** [January 7, 2010, 10:52pm UTC](https://www.ruby-forum.com/t/prevent-certain-inputs-like-user-at-gmail-com/181232/2 "2010-01-07T22:52:12Z")

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On Jan 7, 11:58Â am, tom [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> is there anything out there or am i better of using writing my own “validations”  
> You can try to write your own, but if there’s a _reason_ for users to  
> try to leave email addresses in comments, some of the creative ones  
> will figure out ways around your filter. If it’s really a concern,  
> manual moderation may be the only way to handle the issue.

–Matt J.