ActiveRecord get all columns including those belonging

[ryan bayona]

Hi,
Just new to Rails,, and i have some questions :

How can i use ActiveRecord associations to retrieve all columns and rows including the columns and rows in the referenced table.?

SELECT parents.id, parents.parent_name, kids.id, kids.parent_id, kids.kid_name
FROM parents left join kids on parents.id = kids.parent_id

In PHP in can retrieve all rows returned by this query from all joined tables using mysql_fetch_array() and the output is
parents.id, parents.parent_name, kids.id, kids.parent_id, kids.kid_name

Is there an equivalent of this in RoR?


Here is the AR Associations that i want to retrieve all columns including those belonging to the referenced table

Code:

* = primary key
+ = foreign key

Table : parents
*id
parent_name

Table : kids
*id
+parent_id
kid_name

class Parent < ActiveRecord::Base
   has_many :kids
end

class Kid < ActiveRecord::Base
   belongs_to :parents
end


Thanks!

[Jeff]

On Jun 26, 2:00 am, "ryan bayona" <ryanbay...@gmail.com> wrote:
> Hi,
> Just new to Rails,, and i have some questions :

Welcome!

> How can i use ActiveRecord associations to retrieve all columns and rows
> including the columns and rows in the referenced table.?
>

> *SELECT parents.id, parents.parent_name, kids.id, kids.parent_id,

> kids.kid_name
> FROM parents left join kids on parents.id = kids.parent_id

> *

> In PHP in can retrieve all rows returned by this query from all joined
> tables using mysql_fetch_array() and the output is

> *parents.id, parents.parent_name, kids.id, kids.parent_id, kids.kid_name*

>
> Is there an equivalent of this in RoR?

This is one of the changes in thinking when we switch to Rails. The
belongs_to and has_many lets us not worry about the underlying queries
too much.

For example, if the goal is to get a list of kids given a parent, then
it's this easy:

parent = Parent.find(1) # 1 is the parent_id, use whatever you want
parent.kids.size => returns the number of kids
parent.kids.first.kid_name # returns the name of the first kid

Another example:

kids = Parent.find(1).kids # get all kids for the parent
names = kids.collect { |kid| kid.name } # names is now an array of
names

You may also want to take a look at "Rails for PHP Programmers" by
Pragmatic Press.

Hope this helps?

Jeff
softiesonrails.com
purpleworkshops.com

> Here is the AR Associations that i want to retrieve all columns including
> those belonging to the referenced table
>

> *Code:

>
> * = primary key
> + = foreign key
>
> Table : parents
> *id
> parent_name
>
> Table : kids
> *id
> +parent_id
> kid_name
>
> class Parent < ActiveRecord::Base
>    has_many :kids
> end
>
> class Kid < ActiveRecord::Base
>    belongs_to :parents

> end*
>
> Thanks!

[Harold]

Also try

parent = Parent.find(1, :include => :kids)

Then subsequent calls like Jeff mentions won't actually go to the DB
(they are already loaded)...

[ryanb...@gmail.com]

Im going to try your suggestions. I will also find that book you
mentioned..,

Thank you so much!