Built in (boolean)? method

Rails
1

When creating a boolean attribute in ActiveRecord, you get a ? method
for
free. Sadly, it’s returning false for a true value. Does anyone know
what
might be going on?

From my console (for_charity: true). Same behaviour on Rails 2.3.8 and
2.3.11

ruby-1.8.7-p302 > m.for_charity?
=> false
ruby-1.8.7-p302 > m.for_charity
=> true
ruby-1.8.7-p302 >

Thx in advance

-ants

2

The actual representation of any attribute type in Rails will depend on
the
underlying DBMS as the mapping changes from platform to platform. But
if we
assume we’re talking about SQLite as an example, it uses a SQLite
boolean
which is actually stored as 0 for FALSE or 1 for TRUE, and both of these
are
considered “trueish” values by Ruby.

3

On 4 June 2011 07:47, Ants P. [email protected] wrote:

When creating a boolean attribute in ActiveRecord, you get a ? method for
free. Sadly, it’s returning false for a true value. Does anyone know what
might be going on?
From my console (for_charity: true). Same behaviour on Rails 2.3.8 and
2.3.11
ruby-1.8.7-p302 > m.for_charity?
=> false
ruby-1.8.7-p302 > m.for_charity
=> true
ruby-1.8.7-p302 >

It works ok for me using mysql, could you post the section of
schema.rb for that table?

I have never used the for_charity? syntax though. There does not seem
much point when it is a boolean. Is that syntax documented somewhere?

Colin

4

i know about the storage issue (or at least I thought I did) but what I
am
saying is that the returned values are different between the attribute
for_charity and for_charity?

Surely that has nothing to do with how the values are stored? I sent the
output form console in my original email to show that.

-ants

5

On 5 June 2011 10:15, Colin L. [email protected] wrote:

I have never used the for_charity? syntax though. There does not seem
much point when it is a boolean.

I’ve been using it ever since reading dire warnings in the first
edition of Agile Web D. with Rails:

“[To represent true or false, some databases] use integer columns,
where 0 is false and 1 is true… The problem is that in Ruby the
number 0 and the string “f” are both interpreted as true values in
conditions… To query a column as a boolean value in a condition, you
must append a question mark to the column’s name”

I must confess I was surprised to learn (prompted by this thread) that
Active Record has a feature that emulates boolean columns for
databases that don’t support them natively, so you do get a literal
true or false value out of the attribute, instead of a 1 or 0. And was
even more surprised to learn that this feature was added quite a long
time ago (version 1-ish, AFAICT).

But warnings like the above are still passed on (and in fact are still
present in the current edition of AWDWR). I and others clearly missed
the memo.

Is that syntax documented somewhere?

It’s currently implemented in ActiveRecord::AttributeMethods::Query,
and mentioned in the preamble doc for ActiveRecord::Base (but only as
a way of checking for the presence of attributes, not as a way to
typecast fake boolean columns).

The MySQL connection adaptor’s boolean emulation behaviour is
configurable via
ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans, which
is documented.

Chris

6

On 5 June 2011 21:35, Chris M. [email protected] wrote:

< loads of useful and interesting stuff.>

What a great list, ask some questions and get excellent answers. Thanks
Chris.

Colin

7

On 6 June 2011 19:01, Ants P. [email protected] wrote:

Colin, to answer your earlier question about whether I had a method
overriding one of the attribute calls …

Just for the record I can’t claim the prize for that call, it was Chris
Kottom.

Colin

8

Sorry, I misunderstood the original message. Ran similar tests in my
local
environment with same Ruby / Rails, and wasn’t able to get a similar
outcome. Is there anything in your model that could be overriding the
dynamically created accessor?

9

On 5 June 2011 22:53, Colin L. [email protected] wrote:

“Ruby on Rails: Talk” group.
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For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.

I am soooooooooooo sorry for wasting everyone’s time. I don’t have words
to
say how stupid I am. I know we’re not allowed to swear on this list.

Colin, to answer your earlier question about whether I had a method
overriding one of the attribute calls and the answer is … I obviously
checked before posting whether I had a for_charity? method and the
answer
was yes, I did, but it was commented out. It was old.

The real full answer to your question is … yes I did, but not hard
enough. There was another f*%$^ing for_charity? method off screen that I
was
still using. Of course, pressing n in vim more than once was too much
hard
work for me.

I can’t believe what an idiot I am.

You know, I could write about how stressed I am and how under pressure I
am
to get this thing out of the door (which is all true), but I won’t.
Because
idiot is idiot!!

At least you learnt a bit form Chris so it wasn’t all bad :wink:

Thx for your time everyone and please don’t give up on me. I really am
not
really all that stupid and one day, I might have a sensible question!!

-ants