Parsing an array of objects by attributes in rails 3.2

Question

Is it possible to parse an array of objects to select them by attribute? I have a situation where I need to display all objects of a model grouped by an attribute on the index page. What I had been doing in my controller is this...

#xx_controller.rb

@group1 = City.where(:population => 'big')
@group2 = City.where(:population => 'medium')
@group3 = City.where(:population => 'small')

But I'd prefer to do something like this in the controller...

@cities = City.all

And in my view something along the lines of a query, rather than prepackaged instance variables -

@cities.where....

Any thoughts?

I like the 1 database call way, but then I'd put them in groups in the controller. I'd rename the groups to something like @big_cities, @medium_cities, @small_cities also — AJcodez
– AJcodez, Commented Oct 4, 2012 at 0:41
So I found the answer elsewhere on stack... stackoverflow.com/questions/5269108/… :) — Chris Hawkins
– Chris Hawkins, Commented Oct 4, 2012 at 0:43

Renato Zannon · Accepted Answer · 2012-10-04 00:48:26Z

1

If you don't mind loading everything at once from the database, you can do:

@cities = City.all.group_by(&:population)

Which returns a hash whose keys are the possible values for the population attribute. Then, on your view, you can access the cities on each 'group' by doing @cities['small'], @cities['medium'] and so on.

answered Oct 4, 2012 at 0:48

Renato Zannon

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kits · Accepted Answer · 2012-10-04 00:45:41Z

0

Do you mean something like this?

@cities = City.all

small_cities = @cities.select { |city| city.population == 'small' }
medium_cities = @cities.select { |city| city.population == 'medium' }
big_cities = @cities.select { | city| city.population == 'big' }

answered Oct 4, 2012 at 0:45

kits

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