# Ignoring column on save **URL:** \ **Category:** Rails\ **Created:** [September 19, 2007, 2:30am UTC](https://www.ruby-forum.com/t/ignoring-column-on-save/114944 "2007-09-19T02:30:19Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![andre123](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7ba0ec/32.png) [@andre123](https://www.ruby-forum.com/u/andre123)\ **Post date:** [September 19, 2007, 2:30am UTC](https://www.ruby-forum.com/t/ignoring-column-on-save/114944/1 "2007-09-19T02:30:19Z")
How can I tell Rails to completely ignore one specific column when INSERTing using the save method? I want the database’s default value to be used, but currently Rails is setting it to NULL. ---
**Author:** ![andre123](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7ba0ec/32.png) [@andre123](https://www.ruby-forum.com/u/andre123)\ **Post date:** [September 19, 2007, 9:29am UTC](https://www.ruby-forum.com/t/ignoring-column-on-save/114944/2 "2007-09-19T09:29:54Z")
Andre S. wrote: > How can I tell Rails to completely ignore one specific column when > INSERTing using the save method? > I want the database’s default value to be used, but currently Rails is > setting it to NULL. I don’t believe you can tell Rails to ignore a column on a save (I don’t see any such options in the API docs). When you do a \.new it’ll put in any default values for the attributes at that time. If you don’t alter those attributes it should still have the default values in there. Are you altering the attributes in some way but want to reset them back to their defaults? If so I believe the only way to “reset” them is to set the values of those attributes manually (having saved off the default values before they were altered somewhere). – Michael W. ---
**Author:** ![andre123](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7ba0ec/32.png) [@andre123](https://www.ruby-forum.com/u/andre123)\ **Post date:** [September 19, 2007, 10:42am UTC](https://www.ruby-forum.com/t/ignoring-column-on-save/114944/3 "2007-09-19T10:42:10Z")
On Sep 19, 2007, at 2:29 AM, Andre S. wrote: > How can I tell Rails to completely ignore one specific column when > INSERTing using the save method? > I want the database’s default value to be used, but currently Rails is > setting it to NULL. Rails sets the database default value when you create a new instance of the object, that’s done by attributes\_from\_column\_definition # Initializes the attributes array with keys matching the columns from the linked table and # the values matching the corresponding default value of that column, so # that a new instance, or one populated from a passed-in Hash, still has all the attributes # that instances loaded from the database would. def attributes\_from\_column\_definition self.class.columns.inject({}) do |attributes, column| attributes[column.name] = column.default unless column.name == self.class.primary\_key attributes end end which in turn is called by AR::Base.new. Is your code assigning nils by hand? – fxn ---
**Author:** ![andre123](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7ba0ec/32.png) [@andre123](https://www.ruby-forum.com/u/andre123)\ **Post date:** [September 19, 2007, 1:41pm UTC](https://www.ruby-forum.com/t/ignoring-column-on-save/114944/4 "2007-09-19T13:41:45Z")
On 9/19/07, Xavier N. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > self.class.primary\_key > attributes > end > end > > which in turn is called by AR::Base.new. Is your code assigning nils > by hand? This is the column, database is PostgreSQL: codigo BIGINT UNIQUE NOT NULL DEFAULT nextval(‘customers\_codigo\_seq’), It’s like an auto-incrementing column in MySQL. Currently, I’m not setting it to anything, Rails is setting it to NULL, and PostgreSQL complains that: null value in column “codigo” violates not-null constraint : INSERT INTO customers … It needs to be DEFAULT, without quotes, or not sent at all. Thank you! ---
**Author:** ![andre123](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7ba0ec/32.png) [@andre123](https://www.ruby-forum.com/u/andre123)\ **Post date:** [September 20, 2007, 1:46am UTC](https://www.ruby-forum.com/t/ignoring-column-on-save/114944/5 "2007-09-20T01:46:46Z")
On 9/19/07, Andre S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > of the object, that’s done by attributes\_from\_column\_definition > > attributes[column.name] = column.default unless column.name == > > codigo BIGINT UNIQUE NOT NULL DEFAULT nextval(‘customers\_codigo\_seq’), > > It’s like an auto-incrementing column in MySQL. > > Currently, I’m not setting it to anything, Rails is setting it to > NULL, and PostgreSQL complains that: > > null value in column “codigo” violates not-null constraint : INSERT > INTO customers … > > It needs to be DEFAULT, without quotes, or not sent at all. I wrote a small stored procedure that sets the codigo column when it’s NULL on INSERT. There’s probably a much better way to solve this problem, but I haven’t figured it out yet. Any ideas? Anybody using sequences with PostgreSQL? ---
**Author:** ![andre123](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/7ba0ec/32.png) [@andre123](https://www.ruby-forum.com/u/andre123)\ **Post date:** [September 27, 2007, 6:14pm UTC](https://www.ruby-forum.com/t/ignoring-column-on-save/114944/6 "2007-09-27T18:14:20Z")
Andre S. wrote: > > > self.class.primary\_key > > > It’s like an auto-incrementing column in MySQL. > > > NULL on INSERT. There’s probably a much better way to solve this > > > problem, but I haven’t figured it out yet. Any ideas? Unfortunately, Rails can’t sense default values when they’re result of a function. What it does is merely parse the the text metadata for default value. So in your case the workarounds are either stored procedure (what you did) or PostgreSQL rules on INSERT/UPDATE. – Sava C.