Decimal item gets truncated at DB-storage time

Rails
1

Hi All,

I created a new Expense item. In particular, the value I entered in
the Amount field was 14.99. In the scaffold invocation for this
field, I declared its type to be Decimal.

The log for the creation of this expense record shows
“amount”=>“14.99”

But log for the SQL statement shows:
Create (16.0ms) [0m [0mINSERT INTO expenses (purpose, by,
updated_at, date, type, amount, vendor, created_at)
VALUES(‘fun’, ‘RLM’, ‘2010-03-12 22:11:24’, ‘2010-03-12’, NULL, 14,
‘Ringling Bros’, ‘2010-03-12 22:11:24’)
So the amount has been converted to an integer with the decimal
portion of the input truncated.

What’s the best way to resolve this problem?

Thanks in Advance,
Richard

2

On Fri, 2010-03-12 at 19:44 -0800, RichardOnRails wrote:

Create (16.0ms) [0m [0mINSERT INTO expenses (purpose, by,
updated_at, date, type, amount, vendor, created_at)
VALUES(‘fun’, ‘RLM’, ‘2010-03-12 22:11:24’, ‘2010-03-12’, NULL, 14,
‘Ringling Bros’, ‘2010-03-12 22:11:24’)
So the amount has been converted to an integer with the decimal
portion of the input truncated.

What’s the best way to resolve this problem?

Thanks in Advance,

check the sql db and see how the column is defined…
check db/schema.rb and see how the column is defined…

Craig

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3

Hi Craig,

Thanks for responding.

sql.db
There doesn’t appear to be such a critter in my project, although it
was created with script/scaffold

db\schema.db
create_table “expenses”, :force => true do |t|
[snip]
t.integer “amount”, :limit => 10, :precision => 10, :scale =>
0

But just before I logged in right now, the fundamental cause of my
problem struck me:
When I declared expense:decimal in the scaffold, I didn’t
declare :scale=>10, :precision=>2, which is what I want. So there’s a
new question, I think:

  • Can I declare successive migrations where I drop column and then add
    column, or
  • can I just add those attributes to the column?

I don’t care about the any data in there at the moment: it’s all toy
data for testing.

I look forward to your additional thoughts.

Best wishes,
Richard

4

On Fri, 2010-03-12 at 21:34 -0800, RichardOnRails wrote:

[snip]
  • can I just add those attributes to the column?

I don’t care about the any data in there at the moment: it’s all toy
data for testing.

I look forward to your additional thoughts.

1 - When I said SQL DB, I meant the actual SQL Database that you are
using. i.e. MySQL, SQLite, PostgreSQL, etc. Do you know how to look at
your database?

2 - Get familiar with Rails API…

http://api.rubyonrails.org/

It has answers to so many things that you can look up for reference

and in this case, you probably want to find ActiveRecord::Migrations and
you will find that yes, you can drop/add columns and you can change
columns via migrations.

Craig

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5

Thanks, again, profusely for your response.

< Do you know how to look at your database?

mysql> describe expenses;
±-----------±--------------
| Field | Type
±-----------±--------------
| amount | decimal(10,0)

Can I declare successive migrations where I drop column …
Get familiar with Rails API… http://api.rubyonrails.org/

Thanks for that API. Actually, I’ve had a tab open on

while trying to get a control with drop-down-selection coded … but
that’s for another day.

It has answers to so many things that you will find that yes,
you can drop/add columns and you can change columns via migrations.

Thank goodness for that! But I wasn’t able to find “drop column” and
resorted to
http://www.oracle.com/technology/pub/articles/kern-rails-migrations.html
to find this list:

13 remove_column :albums, :year
14 rename_column :albums, :year_int, :year
15 change_column :albums, :year, :integer, :limit => 4, :null =>
false

which gave me the answer I really wanted: #15

Bottom line: you’re a great resource. You pointed me in the right
directions and I got to Nirvana!

Thanks again, Craig, very much,
Richard