Rails sort columns by column name in another table

Question

I'm using handles_sortable_columns to sort my columns in Rails 3 and was wondering if there is a way to sort by a column in another table other than using a join.

I have a column that is a lookup of the name of a column in another table.

That is, I have cities.country_id as a column and in the View template I do:

@cities.each do |city|
    city.country.name

to display the name.

I would like to be able to sort by this column, but the countries.name, not the cities.country_id.

Does anyone know if this possible with the gem or any other simple way? If so how?

The only thing I can think of is to do an IF statement in the controller and catch the sorting by country and then run a different query using a join for that, but that's ugly and error-prone, was hoping for something more elegant.

Thanks.

Webjedi · Accepted Answer · 2012-06-28 14:26:37Z

1

Can you override to the to_s on the country model to return the name, then sort by that in the controller?

In your country model override to_s by:

def to_s
 country.name
end

Then in your controller

@sorted_cities = @cities.sort_by { |obj| obj.country.to_s }

edited Jun 28, 2012 at 14:26

answered Jun 27, 2012 at 17:44

Webjedi

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2 Comments

kakubei Over a year ago

Sorry, I don't understand what you mean

kakubei Over a year ago

This is really interesting. I'd never seen it before. In the end I went with a join so I could also query on the country name, but thanks a lot for pointing this out. I'll have to give it a try.

okliv · Accepted Answer · 2013-03-11 14:17:49Z

1

in addition to Webjedi answer..

 @sorted_cities = @cities.includes(:country).sort_by { |obj| obj.country.to_s } #for eager loading

answered Mar 11, 2013 at 14:17

okliv

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1 Comment

maletor Over a year ago

Don't do this. You should use the database.

kakubei · Accepted Answer · 2012-08-07 09:15:28Z

0

In the end I decided to use a join to get the right data to begin with. While Webjedi's answer is quite intriguing I didn't want to override any built-in functions, but it's good to know I can do that.

The code looks like this:

@countries = Country.select('countries.*, continents.name AS continent_name').joins{continent}.search(params[:term]).order(order).page(params[:page])

answered Aug 7, 2012 at 9:15

kakubei

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