How do I discover available methods in Rails documentation?

Question

I am new to Rails, and I am finding it extremely opaque. I have a copy of the latest Agile Web Development with Rails, but my worry is that without this book I would be completely lost.

For example, following the depot example in the book, when it comes to adding validation to the model, you do

class Product < ActiveRecord::Base

  validates :title, :description, :image_url, :presence => true

end

Seems easy enough, except that without the AWDwR book I would never have figured this out. There is nothing in the ActiveRecord::Base documentation that mentions the validates method.

It seems to me that with Rails you are just supposed to mysteriously know what methods are available at any given point in a project. But if you don't know, how are you supposed to find out (apart from memorizing a 500+ page book)?

I can phrase the question another way: In my Product class, I have available to me a method named validates. How is this method made available to my Products class? Even knowing that it is defined in ActiveModel::Validations::ClassMethods (I know this because I looked it up) I cannot figure out how it has been made available to my Product class.

+1 I understand where you're coming from. Opaque sums it up nicely. Notice the plethora of questions on SO about Rails - a lot of them stem from the fact that Rails really does make you feel "out in the cold". The documentation is nowhere near the quality it should be. Everything is scattered, no cohesion. Much as I like Rails, I'm wondering why the documentation isn't better. Maybe because everyone that knows Rails just wants to write their own theories and make money selling books. Wish there was a document structure like MSDN! — Zabba
– Zabba, Commented Mar 21, 2011 at 5:27

Mike Lewis · Accepted Answer · 2011-03-21 03:25:05Z

1

I use http://railsapi.com/ on a daily basis, I hope you find it helpful as well!

answered Mar 21, 2011 at 3:25

Mike Lewis

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1 Comment

Dave Isaacs Over a year ago

I looked at railsapi.com and found it almost useless in answering my question. Type in "ActiveRecord::Base" and you get no results.

Anthony Bishopric · Accepted Answer · 2011-03-21 06:52:11Z

1

the authoritative site too - http://api.rubyonrails.org

answered Mar 21, 2011 at 6:52

Anthony Bishopric

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2 Comments

Dave Isaacs Over a year ago

Again, how does this site help me discover that there is a validates method in my Product class. And this is only a trivial example. I am less than 1/5th through AWDwR and have come across many places where the only reason I know what to do is because the book told me. When I try to dig to find out why what I've been told works, I get nowhere.

Anthony Bishopric Over a year ago

This is a fair point, and something I've definitely thought about while learning RoR. Rails is so convention driven that often times I find myself "guessing" that a method exists and then searching for it (and finding it). For example, the view helper methods (link_to, form_for, image_tag, etc) all follow fairly similar and familiar conventions.

MoFlo · Accepted Answer · 2012-08-02 02:17:35Z

1

Rails ActiveRecord does support model introspection of columns and methods, just use the following

$ rails console
1.9.3> Product.columns
1.9.3> => [#<ActiveRecord::ConnectionAdapters::PostgreSQLColumn:0x007fe853d2c1f0 @name="id", @sql_type="integer", @null=false, ...

1.9.3> Product.methods
1.9.3> => [:_validators, :before_add_for_memberships?, :before_add_for_memberships=, :before_add_for_memberships, :after_add_for_memberships?, ...

That would theoretically allow you to discover likely methods (or columns) which may be of interest and then you can use the API doc sources referenced in other answers.

answered Aug 2, 2012 at 2:17

MoFlo

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Dave Isaacs · Accepted Answer · 2012-02-06 20:16:04Z

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It's been almost a year, and I can now look back and say that the best resources I found for learning rails are the Rails Guides at http://guides.rubyonrails.org/. They tie everything together very nicely, provide some examples, and give me an entry point into the API documentation (as opposed to flailing around randomly like I did when I first started).

answered Feb 6, 2012 at 20:16

Dave Isaacs

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