Blog Screencast Questions

Rails
1

In the blog screencast the commentator creates two model classes,
‘Post’ and ‘Comment’. Note that both of these model classes are
singular. However, when he creates the association he says in the
Post model ‘has_many(:comments)’. IOW, he uses the plural form of the
Comment model and lowers the case of the the model class name.
However, when he does the association within the Comment class he says
‘belongs_to(:post)’. Here he does not pluralize post although he does
(as expected) lower the case. This perplexes me.

Now, I want to follow this example; but, I want my model classes to be
named ‘BlogPost’ and ‘BlogComment’ respectively in order to avoid
potential namespace conflicts. I am not getting my associations to
work. I think that I may be having trouble with the naming. In the
BlogPost class do I say, ‘has_many(:blogComments)’ and in the
BlogComment class say, ‘belongs_to(:blogPost)’? This pluralizing
thing is really confusing me. Additionally, I’m beginning to wonder
if I don’t need to introduce some underscores, e.g., ‘blog_comment’ or
‘blog_comments’. Anyway, I’m obviously very confused. Can someome
please straighten me out on exactly how these associations should be
formed?

Thanks for any input.

      ... doug
2

On Mon, Jun 15, 2009 at 11:31 AM, doug[email protected] wrote:

In the blog screencast the commentator creates two model classes,
‘Post’ and ‘Comment’. Note that both of these model classes are
singular. However, when he creates the association he says in the
Post model ‘has_many(:comments)’. IOW, he uses the plural form of the
Comment model and lowers the case of the the model class name.
However, when he does the association within the Comment class he says
‘belongs_to(:post)’. Here he does not pluralize post although he does
(as expected) lower the case. This perplexes me.

The rules are pretty obvious once you realize that the goal was to
follow normal English syntax.

I wouldn’t say “I have many problem.” Neither would I say “I have a
problems”

The other Rails convention here is the relationship between Ruby
constant names (and class names and module names are constants) and
the symbols Rails uses to talk about an instance or instances of a
class.

Ruby requires constants to be named with an initial capital letter.
In forming compound words, the convention is to use what is called
“camel-case”, as in ActionController, or BlogPost, it’s called camel
case because the capital letters form ‘humps.’

But other ruby names use lowercase, and most Rubyists use underscores
to combine words in these, as in first_name. Most folks call this
‘snake case’.

Now, I want to follow this example; but, I want my model classes to be
named ‘BlogPost’ and ‘BlogComment’ respectively in order to avoid
potential namespace conflicts. I am not getting my associations to
work. I think that I may be having trouble with the naming. In the
BlogPost class do I say, ‘has_many(:blogComments)’ and in the
BlogComment class say, ‘belongs_to(:blogPost)’?

So following both conventions this should be

class BlogPost < ActiveRecord::Base
has_many :blog_comments
end

class BlogComment < ActiveRecord::Base
belongs_to :blog_post
end

This pluralizing
thing is really confusing me. Additionally, I’m beginning to wonder
if I don’t need to introduce some underscores, e.g., ‘blog_comment’ or
‘blog_comments’. Anyway, I’m obviously very confused. Can someome
please straighten me out on exactly how these associations should be
formed?

I hope that this post helped do just that.

–
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Twitter: http://twitter.com/RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale

3

On Jun 15, 4:31 pm, doug [email protected] wrote:

In the blog screencast the commentator creates two model classes,
‘Post’ and ‘Comment’. Note that both of these model classes are
singular. However, when he creates the association he says in the
Post model ‘has_many(:comments)’. IOW, he uses the plural form of the
Comment model and lowers the case of the the model class name.
However, when he does the association within the Comment class he says
‘belongs_to(:post)’. Here he does not pluralize post although he does
(as expected) lower the case. This perplexes me.

comments is pluralized because a post has many comments (1:n
association)

post is singular because a comment belongs to a single post, not
several.

please straighten me out on exactly how these associations should be
formed?

underscored: blog_comments; blog_post

Fred

4

Thanks for the input, Rick and Fred.

comments is pluralized because a post has many comments (1:n
association)

post is singular because a comment belongs to a single post, not
several.

OK. From a grammatical perspective that certainly makes a lot of
sense. However, it sure messes with my mind from a programming
perspective. Personally, I’d much prefer to be able to refer to
something pretty much as I defined it and not have to worry about what
is going to be altered and what isn’t. I understand that with Ruby
there is going to have to be some flexibility in that regard because
of Ruby naming rules such as, “constants must begin with a capital
letter”.

Please correct me if I’m wrong; but, this is an ActiveRecord issue,
not a pure Rails issue, right?

Is there anyway that I can turn off the pluralization behavior? That
would go a long way towards retaining order in my life.

As far as the camelcase and underscore thing goes, how about I just
define my model classes to be ‘Blog_post’ and ‘Blog_comment’
respectively? Then, with the pluralization turned off (if that’s
possible),
the only variation that I would have to worry about relates to the
case of the initial letter. Dealing with that should be pretty easy
because it just requires that one follow the Ruby naming rules. What
do you think?

     ... doug
5

On Jun 15, 10:42 pm, djolley [email protected] wrote:

perspective. Personally, I’d much prefer to be able to refer to
something pretty much as I defined it and not have to worry about what
is going to be altered and what isn’t. I understand that with Ruby
there is going to have to be some flexibility in that regard because
of Ruby naming rules such as, “constants must begin with a capital
letter”.

Please correct me if I’m wrong; but, this is an ActiveRecord issue,
not a pure Rails issue, right?

It’s a choice made by the people who wrote active record.

Is there anyway that I can turn off the pluralization behavior? That
would go a long way towards retaining order in my life.

Definitely no on/off switch you can through. I suppose you could try
messing with inflector rules to make singularising/pluralising a no-op

As far as the camelcase and underscore thing goes, how about I just
define my model classes to be ‘Blog_post’ and ‘Blog_comment’
respectively? Then, with the pluralization turned off (if that’s
possible),

Class names should be camel cased: BlogPost. Funny things might
happened if you called them Blog_post.

Fred

6

Doug J. wrote:
[…]

OK. So, it sounds like I’m stuck to remember and apply the rules.
I’ll probably get used to it – someday. :slight_smile:

Think in English, not programmerspeak, and it will all be effortless.
(Thinking in English will probably also lead to writing more readable
code in general…)

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

7

Class names should be camel cased: BlogPost. Funny things might
happened if you called them Blog_post.

OK. So, it sounds like I’m stuck to remember and apply the rules.
I’ll probably get used to it – someday. :slight_smile:

Thanks for the input.

     ... doug
8

Think in English, not programmerspeak, and it will all be effortless.
(Thinking in English will probably also lead to writing more readable
code in general…)

I totally understand the advantages of this approach. My concern is
that when something goes wrong it could compound the difficulty of
locating the problem. It’s difficult enough trying to locate typos in
variable names in interpreted languages without having the language
introduce its own variations on spelling. But, the whole thing is
neither here nor there. That’s the way it is. There is no way to
disable that “feature”; and so, I have to live with it. Thanks for
the input.

       ... doug
9

Doug J. wrote:

Is there anyway that I can turn off the pluralization behavior? That
would go a long way towards retaining order in my life.

It might feel that way, but as soon as you start sharing code others, or
reading more of other peoples code, there would always have to be that
translation between “I do it this way, you do it that way” that would
just increase confusion I think. You know you turned off pluralization,
but other people reading your code will likely have many “WTH?” moments.

Sit back, relax, and prepare to be assimilated…

10

Actually, it’s the framework doing that.

Actually, if I am not mistaken, it’s not the framework (Rails). It’s
ActiveRecord. I certainly wouldn’t want to give up ActiveRecord.
That would be asking too much! :slight_smile:

Perhaps you shouldn’t be using Rails if this really bothers you.

Well, I must admit that it does bother me. However, maybe I’m just
too set in my ways. Maybe I’ll get used to it after a while. Anyway,
I’m going to give it a fair try before I through in the towel. There
are too many other things about Rails that I really like.

As one commentator put it:

Sit back, relax, and prepare to be assimilated…

That’s exactly what I plan on doing. Besides that, his point about
sharing code is well taken.

Thanks again for all the input.

       ... doug
11

Doug J. wrote:

My concern is
that when something goes wrong it could compound the difficulty of
locating the problem.

I’ve never had this be an issue at all!

It’s difficult enough trying to locate typos in
variable names in interpreted languages

(Nitpick: this has nothing to do with Ruby being interpreted.
Interpreted languages can require variable declarations, while compiled
ones need not necessarily.)

without having the language
introduce its own variations on spelling.

Actually, it’s the framework doing that…but again, the whole thing is
pretty transparent if you speak English and know Ruby’s capitalization
rules.

But, the whole thing is
neither here nor there. That’s the way it is. There is no way to
disable that “feature”; and so, I have to live with it.

Perhaps you shouldn’t be using Rails if this really bothers you. Rails
is a great framework, but it does a great deal of magic – almost too
much. There are other Ruby Web frameworks such as Merb and Ramaze that
may be more to your taste.

Personally, I like the Rails inflections. They work by well-defined
rules, and knowing what’s what has never been a problem for me in
practice.

Thanks for
the input.

       ... doug

You’re welcome!

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

12

Doug J. wrote:

Actually, it’s the framework doing that.

Actually, if I am not mistaken, it’s not the framework (Rails). It’s
ActiveRecord. I certainly wouldn’t want to give up ActiveRecord.
That would be asking too much! :slight_smile:

ActiveRecord is usually considered part of Rails, although it can be
used on its own.

Perhaps you shouldn’t be using Rails if this really bothers you.

Well, I must admit that it does bother me.

On the one hand, it would be nice to have a choice. On the other hand,
unless you have models with closely similar names (which is a terrible
idea anyway), there’s no issue.

Rails is an opinionated framework. It does a lot of stuff for you, but
in return it wants to do things its way.

However, maybe I’m just
too set in my ways.

It sounds like you’re anticipating a problem where there actually isn’t
one.

Maybe I’ll get used to it after a while.

Have you worked much with Ruby in any context? I get the feeling this
sort of tricky metaprogramming is a little more accepted in Ruby than in
many other languages…

Anyway,
I’m going to give it a fair try before I through in the towel.

OK

There
are too many other things about Rails that I really like.

:slight_smile:

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]