Add missing information, ref[#522c0fd]

[kuldeepaggarwal]

No description provided.

[rafaelfranca]

I really did't understand what you are trying to say here. Why I would talk about id if it will be always present?

[schneems]

I think this is because rails will treat "id" as an alias for primary key. From read_attribute definition:

            if name == 'id' && self.class.primary_key != name
              read_attribute(self.class.primary_key)
            end

I believe others will have the same question though. So maybe instead we could write:

# <tt>ActiveModel::MissingAttributeError</tt> if the identified attribute is missing.
# Note: +:id+ will default to the record's primary key if not present

Or something similar. It isn't that :id is special cased (and will always be present) but that if not present it will look for primary_key, which could still possibly not exist if there is a problem with migrations or the database.

[rafaelfranca]

Actually I think it is not about primary key being not present. It always is.

[rafaelfranca]

Maybe we should do:

# Note: +:id+ is always present.

[schneems]

👍

[kuldeepaggarwal]

this seems good 😄

[rafaelfranca]

Right. Please update the PR.

[kuldeepaggarwal]

Will update it.

Thanks and Regards
KD
On May 14, 2014 1:05 AM, "Rafael Mendonça França" notifications@github.com
wrote:

In activerecord/lib/active_record/attribute_methods.rb:

@@ -357,7 +357,7 @@ def column_for_attribute(name)

 # Returns the value of the attribute identified by

attr_name after it has been typecast (for example,
# "2004-12-12" in a date column is cast to a date object, like
Date.new(2004, 12, 12)). It raises

• ActiveModel::MissingAttributeError if the identified

attribute is missing.

• ActiveModel::MissingAttributeError if the identified

attribute is missing except +id+.

Right. Please update the PR.

—
Reply to this email directly or view it on GitHub.

[kuldeepaggarwal]

Because in the below example:

person = Person.select('id').first
person[:name]            # => ActiveModel::MissingAttributeError: missing attribute: name

but if we will fetch only name then id wont raise any exception

person = Person.select('name').first
person[:id]            # => nil (this will not raise any exception)

[rafaelfranca]

It is because the "the identified attribute is not missing". So the documentation seems correct to me.

[kuldeepaggarwal]

@rafaelfranca updated.