ActiveRecord Question: Disabling Boolean Emulation

rubyonrails-talk
1

Hello everyone, I've got a question for the ActiveRecord gurus.

ActiveRecord version: 2.3.4 ActiveRecord adapter: mysql

I'm accessing a database originally designed as the back-end data- store for a Microsoft Access-based GUI application (using "linked" tables). MS Access, if using linked tables to use a MySQL database wants its boolean fields, like ActiveRecord, to by TINYINT(1) fields. However, is makes the field "signed" and uses 0 for false and -1 for true.

I've taken several approaches to interfacing with boolean fields in this database in an interoperable way (keeping boolean true values as -1). What seems like it should be so easy/simple has yet yield a clean solution (to me at least).

My Example Table (tblImages):

ImageID, UNSIGNED INTEGER, AUTOINCREMENT, PRI-KEY IsFixed, TINYINT, DEFAULT 0

ActiveRecord class:

class Image < ActiveRecord::Base   set_table_name 'tblImages'   set_primary_key 'ImageID'   def fixed     self.IsFixed_before_type_cast == "-1"   end   def fixed=(val)     self[:IsFixed] = (val ? '-1' : '0')   end end

The above code is just one of the many approaches I've taken. I always get so close yet so far. Reading the value is easy by getting it prior to type-casting and interpreting it how I want. However, coercing ActiveRecord (and the MySQL adapter) to issue an "UPDATE tblImage SET IsFixed = -1 ..." seem all but impossible when I issue a save! on an instance.

So, is there any way to tell ActiveRecord (or the MySQL adapter) to simply disable its boolean emulation on a given field (or even the whole table or database)? Or, does anyone have any alternate ideas that might work instead or even better?

Thanks for your help!

2

Why? How are you trying and why does it fail?

You can easily change the values in a before_save filter.

3

I believe you can do that in the adapter itself. You should be able to find it under your activerecord folder (in my PC: C:\ruby\lib\ruby\gems \1.8\gems\activerecord-2.2.2\lib\active_record\connection_adapters \mysql_adapter.rb). Look for "class MysqlAdapter < AbstractAdapter" in the code and you'll see this line:

      self.emulate_booleans = true

Change the line to:

      self.emulate_booleans = false

and see what happens.