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Don't use 'type' as a field in a Rails database

I'm working on a new rails application. In one of the tables I have a field called 'type'. Everything was going fine, but whenever I set the 'type' field and saved the record it ignored the contents and set it to NULL. I couldn't figure it out.

Tangentially, I had set a bunch of fields to be 'string' and these are translated to be varchar(255) in the sqlite database and I wanted to test what happened if I went over the 255 character limit. So I typed in a string 260 characters long into the 'type' field using an external database app and saved the record. It saved just fine, and kept all the characters. Now I thought, let me load this in my rails app and see if it still sets it to NULL. I loaded it and got back this error message:


ActiveRecord::SubclassNotFound in ItemsController#show

The single-table inheritance mechanism failed to locate the subclass: 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0'. This error is raised because the column 'type' is reserved for storing the class in case of inheritance. Please rename this column if you didn't intend it to be used for storing the inheritance class or overwrite Item.inheritance_column to use another column for that information.


Now they tell us !

Convention : good.
Informative error messages : good.
Not telling us what the convention is : bad

Bad Rails people, bad rails people.

To peek into the database I'm using the Sqlite manager plugin for firefox by Mrinal Kant. Its awesome.

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