# How to simulate a column that do not exists in a model **URL:** \ **Category:** Rails\ **Created:** [August 31, 2010, 8:49pm UTC](https://www.ruby-forum.com/t/how-to-simulate-a-column-that-do-not-exists-in-a-model/194192 "2010-08-31T20:49:51Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![lucas\_franceschi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/c6cbf5/32.png) [@lucas\_franceschi](https://www.ruby-forum.com/u/lucas_franceschi)\ **Post date:** [August 31, 2010, 8:49pm UTC](https://www.ruby-forum.com/t/how-to-simulate-a-column-that-do-not-exists-in-a-model/194192/1 "2010-08-31T20:49:51Z")
Hello there… what i am trying to do, is to consider a new column in my model, a column that do not exist in the database, and will not be created. imagine, for instance, this case: I have a table that store a number and a string, lets call it ‘words’ * * * ## words ## int times(PK) char name imagine Word as an instance of the model, i will have access to these: Word.times Word.name what if i wanted a new column, some like Word.complete imagine that this column would store that ‘char’ for many times as is defined int the ‘times’ column… like this Word.times = 3 Word.name = a Word.complete = aaa got it? i wont store that data, but generate it based on the data that is stored. any idea??? did any of you guys see this situation before??? – Lucas Franceschi Desenvolvedor SGI Sistemas (049) 9922-3360 ---
**Author:** ![lucas\_franceschi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/c6cbf5/32.png) [@lucas\_franceschi](https://www.ruby-forum.com/u/lucas_franceschi)\ **Post date:** [August 31, 2010, 9:01pm UTC](https://www.ruby-forum.com/t/how-to-simulate-a-column-that-do-not-exists-in-a-model/194192/2 "2010-08-31T21:01:41Z")
lucas franceschi wrote: > Word.complete = aaa Word is the model class - it doesn’t store values. If word is an instance, simply write: word[:complete] = aaa ---
**Author:** ![lucas\_franceschi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/c6cbf5/32.png) [@lucas\_franceschi](https://www.ruby-forum.com/u/lucas_franceschi)\ **Post date:** [August 31, 2010, 9:08pm UTC](https://www.ruby-forum.com/t/how-to-simulate-a-column-that-do-not-exists-in-a-model/194192/3 "2010-08-31T21:08:35Z")
you didn’t get it… the point is… i want Word.complete ## to already be defined, so that in the controller i could use the “complete” column as if it was a real column… Lucas Franceschi Desenvolvedor SGI Sistemas (049) 9922-3360 ---
**Author:** ![lucas\_franceschi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/c6cbf5/32.png) [@lucas\_franceschi](https://www.ruby-forum.com/u/lucas_franceschi)\ **Post date:** [August 31, 2010, 9:13pm UTC](https://www.ruby-forum.com/t/how-to-simulate-a-column-that-do-not-exists-in-a-model/194192/4 "2010-08-31T21:13:17Z")
correction - you will need to check that both name and times\_repeated are not nil def complete self.name \* self.times\_repeated if self.name && self.times\_repeated end strictly speaking the “self.” isn’t needed either, but it does make the intention clearer… ---
**Author:** ![lucas\_franceschi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/c6cbf5/32.png) [@lucas\_franceschi](https://www.ruby-forum.com/u/lucas_franceschi)\ **Post date:** [August 31, 2010, 9:32pm UTC](https://www.ruby-forum.com/t/how-to-simulate-a-column-that-do-not-exists-in-a-model/194192/5 "2010-08-31T21:32:37Z")
just look up attr\_accessor method, if used within a model on a non existant field in the model, it will create a “pseudo” field. Do not forget to make accessible. ---
**Author:** ![lucas\_franceschi](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/c6cbf5/32.png) [@lucas\_franceschi](https://www.ruby-forum.com/u/lucas_franceschi)\ **Post date:** [August 31, 2010, 9:09pm UTC](https://www.ruby-forum.com/t/how-to-simulate-a-column-that-do-not-exists-in-a-model/194192/6 "2010-08-31T21:09:46Z")
On 31 August 2010 19:48, lucas franceschi [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Word.times = 3 > Word.name = a > Word.complete = aaa > got it? > i wont store that data, but generate it based on the data that is stored. > any idea??? > did any of you guys see this situation before??? once or twice… what you’re after is a “method”… (you may run into trouble if you try to call your column ‘times’, I’ll use ‘times\_repeated’ in this example) # word.rb def complete self.name \* self.times\_repeated if self.name end I recommend going through some Ruby tutorials - the “Ruby for Rails” book has a good coverage of getting started through to intermediate use.