ActiveRecord get all columns including those belonging

Rails
1

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!

2

On Jun 26, 2:00 am, “ryan bayona” [email protected] wrote:

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

Welcome!

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

purpleworkshops.com

3

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)…

4

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

Thank you so much!