ActiveRecord is treating attribute as Integer when it's Decimal in MySQL

Question

I feel like I'm taking crazy pills here. I have a MySQL-backed ActiveRecord class and a number of the attributes are reported in Rails as type Integer:

Device.last.score.class # returns `Fixnum`

MySQL reports the column being of type decimal(10,0).

What am I missing here? Even tried a call to reset_column_information. Migration looks correct and schema file looks OK too.

Note: this issue wasn't happening in dev, where I'm using SQLite.

Here is my migration:

class AddScoreColumnToDevices < ActiveRecord::Migration
    def change  
        add_column :devices, :score, :decimal
    end
end

Assuming you have some records in there , what does Device.first.score.class report? (instead of Device.new) — Michael Berkowski
– Michael Berkowski, Commented Sep 12, 2013 at 19:12
Fixnum as well. I was incorrect above, Device.new.score.class actually returns NilClass for obvious reasons. Fixing that now. — YWCA Hello
– YWCA Hello, Commented Sep 12, 2013 at 19:18
Can you save a new Device with a float/decimal score? Device.create(score: 11.11)? — Carlos Drew
– Carlos Drew, Commented Sep 12, 2013 at 23:02
Also, I would suggest posting your Device model code and the migration you used to create the Device table/score column. Such will help answering your question more quickly... — Carlos Drew
– Carlos Drew, Commented Sep 12, 2013 at 23:03
@CarlosDrew New records have the same issue. I posted the migration above; it's extremely vanilla. I did not include the class definition because I don't even make mention of the :score attribute in it. It's a basic model class that inherits directly from ActiveRecord::Base. — YWCA Hello
– YWCA Hello, Commented Sep 13, 2013 at 16:17

Carlos Drew · Accepted Answer · 2013-09-13 16:42:51Z

The migration did it for me! Thank you!

The defaults for a newly migrated :decimal are :precision => 0 and :scale => 0, which will result in a MySQL decimal accepting nothing after the decimal point.

Ruby will see that number, with nothing after the decimal point, as a Fixnum, which is what you are observing.

So, you need to write a new migration to alter the column and give the decimal precision and scale > 0.

change_column :devices, :score, :decimal, :precision => 10, :scale => 10

References:
ActiveRecord ConnectionAdapter TableDefinition #column
decimal precision and scale
old reference on MySQL column<->Ruby datatype mapping

Collectives™ on Stack Overflow

ActiveRecord is treating attribute as Integer when it's Decimal in MySQL

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related