Don't use 'type' as a DB column name ..

[Commander Johnson]

Hi,

I'm creating a simple Migration that adds test data to my database.

A Form has many Elements and every Element belongs to a Form. An element has the mandatory columns name, type and value.

---

class AddTestData < ActiveRecord::Migration

  def self.up

    Form.delete_all

    Element.delete_all

    bert = Form.create(:name => "Bert's Form")

    Element.create(:form => bert, :name => 'First Name', :type => 'text', :value => '')

    Element.create(:form => bert, :name => 'Last Name', :type => 'text', :value => '')

    

    ernie = Form.create(:name => "Ernie's Form")

    Element.create(:form => ernie, :name => 'Your Name', :type => 'text', :value => '')

    Element.create(:form => ernie, :name => 'E-mail', :type => 'text', :value => '')

  end

  def self.down

    Form.delete_all

    Element.delete_all

  end

end

---

Gives the error:

Mysql::Error: #23000Column 'type' cannot be null: INSERT INTO `elements` (`form_id`, `ordering`, `name`, `title`, `type`, `value`, `flags`, `created_at`, `updated_at`) VALUES(2, NULL, 'First Name', NULL, NULL, '', NULL, '2008-09-16 13:59:36', '2008-09-16 13:59:36')

As you can see, the 'type' column somehow isn't inserted. 

I had similar issues when trying to add a column called 'timestamp'.

Best regards,

CmdJohnson

[Peter De Berdt]

"type" is a reserved field name for single table inheritance (STI): http://wiki.rubyonrails.com/rails/pages/MagicFieldNames

We're using "timestamp" without a problem in some of our apps, so that must be another issue.

Best regards

Peter De Berdt

[Robert Walker]

Commander Johnson wrote:
...snip...

> Gives the error:
>
> Mysql::Error: #23000Column 'type' cannot be null: INSERT INTO `elements`
> (`form_id`, `ordering`, `name`, `title`, `type`, `value`, `flags`,
> `created_at`, `updated_at`) VALUES(2, NULL, 'First Name', NULL, NULL,
> '',
> NULL, '2008-09-16 13:59:36', '2008-09-16 13:59:36')
>
> As you can see, the 'type' column somehow isn't inserted.

From looking at that error it's clear that the 5th value sent is NULL
which is your `type` column. So your problem is not with MySQL. Given
that Rails uses a "type" column for single-table inheritance, maybe that
has something to do with your issue.

> I had similar issues when trying to add a column called 'timestamp'.

MySQL has a TIMESTAMP data type. I would guess that you could use that
as a column name as long as it's quoted properly (i.e. `timestamp`).

I tend to avoid naming columns with likely database keywords (type,
timestamp, data, time, number, text, etc.).

P.S. I also avoid using TIMESTAMP data type in MySQL. It's may not
behave as you might expect it to. If a column of that type is not send
in a UPDATE statement it will automatically update itself to the current
time of the database server.
--
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