# Active Record associations wiredness

**URL:** <https://www.ruby-forum.com/t/active-record-associations-wiredness/117235>\
**Category:** Rails\
**Created:** [October 15, 2007, 6:26am UTC](https://www.ruby-forum.com/t/active-record-associations-wiredness/117235 "2007-10-15T06:26:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![dueckes](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ec9cab/32.png) [@dueckes](https://www.ruby-forum.com/u/dueckes)\
**Post date:** [October 15, 2007, 6:26am UTC](https://www.ruby-forum.com/t/active-record-associations-wiredness/117235/1 "2007-10-15T06:26:35Z")

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Hi all,

```
Can anyone explain why line 1372 of lib/active_record/

```

associations.rb performs a String equality check as opposed to a more  
conventional Object equality check:

return nil if record.id.to\_s != join.parent.record\_id(row).to\_s or  
row[join.aliased\_primary\_key].nil?

I stumbled across this when attempting to monkey patch the Oracle  
Adapter as I noticed that on some occasions columns were incorrectly  
interpreted as Floats instead of Integer.

Any answers much appreciated.

Kind Regards,

Matthew Ueckerman

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**Author:** ![dueckes](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ec9cab/32.png) [@dueckes](https://www.ruby-forum.com/u/dueckes)\
**Post date:** [October 15, 2007, 9:25am UTC](https://www.ruby-forum.com/t/active-record-associations-wiredness/117235/2 "2007-10-15T09:25:26Z")

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On 15 Oct 2007, at 05:26, dueckes wrote:

> I stumbled across this when attempting to monkey patch the Oracle  
> Adapter as I noticed that on some occasions columns were incorrectly  
> interpreted as Floats instead of Integer.

Because of the thing where ids are sometimes integers (eg User.find  
123) and sometimes strings.

Fred

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<div class="post-metadata">

**Author:** ![dueckes](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ec9cab/32.png) [@dueckes](https://www.ruby-forum.com/u/dueckes)\
**Post date:** [October 16, 2007, 3:43am UTC](https://www.ruby-forum.com/t/active-record-associations-wiredness/117235/3 "2007-10-16T03:43:28Z")

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Thanks for the response Fred.

Perhaps some more context would help. Executing the following  
triggers this code:

Customer.find(1, :include =\> :orders)

The include clause adds a join to the resulting SQL so that the  
Customer and it’s related Orders can be retrieved via a single query.  
This code comes into play after the query executes and acts on the  
result set; it appears to be verifying the child (Order) has a  
matching foreign key to the parent (Customer) in the result set.

So here’s my original question with some points/Q’s thrown in:

1. The verification appears to be redundant as the query contains a  
where clause limiting the result set to the parent id.
2. It uses an unconventional equality check via String conversion,  
why (as per my original question)?
3. Invoking record.id causes adapter specific logic to execute that  
may convert the type of the value to some other type, however  
join.parent.record\_id(row) does not perform that same logic - I  
suspect this is a defect? As a consequence of this I’ve seen cases  
where 1 != 1.0 (for instance)

Again, any help much appreciated.

Regards,

Matthew

On Oct 15, 5:24 pm, Frederick C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)

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<div class="post-metadata">

**Author:** ![dueckes](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/ec9cab/32.png) [@dueckes](https://www.ruby-forum.com/u/dueckes)\
**Post date:** [October 16, 2007, 11:23am UTC](https://www.ruby-forum.com/t/active-record-associations-wiredness/117235/4 "2007-10-16T11:23:41Z")

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On 16 Oct 2007, at 02:42, dueckes wrote:

> This code comes into play after the query executes and acts on the  
> result set; it appears to be verifying the child (Order) has a  
> matching foreign key to the parent (Customer) in the result set.
> 
> So here’s my original question with some points/Q’s thrown in:
> 
> 1. The verification appears to be redundant as the query contains a  
> where clause limiting the result set to the parent id.

In your case yes: there is only one parent, but not in the case when  
you’ve got Customer.find(1,2,3, :include =\> :orders) or Customer.find  
(1, :include =\> {:orders =\> :products})

> 1. It uses an unconventional equality check via String conversion,  
> why (as per my original question)?
> 2. Invoking record.id causes adapter specific logic to execute that  
> may convert the type of the value to some other type, however  
> join.parent.record\_id(row) does not perform that same logic - I  
> suspect this is a defect? As a consequence of this I’ve seen cases  
> where 1 != 1.0 (for instance)

The main thing is to avoid instatiating more AR objects than are  
needed, the way :include works more rows are returned than there are  
objects emerging on the other end, eg if the customer has 10 orders,  
you don’t want to instatiate the customer 10 times. I expect 2. is an  
attempt to make this work most of the time without the adapter  
specific logic from record.id.

The short answer is that :include is usually quite overcomplicated  
(as someone who also once read through the JoinBase / JoinDependency  
code you have my sympathy). There is a simple solution in the  
pipeline, but it’s not quite ready yet.

Fred