Filter nil and empty values from an array in rails 3.2

Question

I have a table called Materials and I have created a search form. In the form I want to have select boxes containing the names of the search options. So for example, if you want to search by subject, I want a dropdown with one of each of the subjects. I have code for this that works:

@subject = Material.unscoped.select(:subject).where("materials.subject IS NOT NULL
and materials.subject != '' ").uniq

This gives me what I want with the following form helper:

<%= select_tag "subject", options_from_collection_for_select(@subject, "subject", 
"subject"), :include_blank => true, :class => "input_field" %>

BUT - I now want to select only those subjects from Materials that are shared. So I selected the shared Materials using:

@shared = Material.where(:status => 'shared')

And then ran this code:

@subject = @shared.unscoped.select(:subject).where("@shared.subject IS NOT NULL
and @shared.subject != '' ").uniq

Which doesn't work. I assume it's because the sql code can't understand the @shared object. But how to do this?

Note:

I tried using:

@subject = @shared.uniq.pluck(:subject).reject! { |s| s.empty? }

This gives an array of the right fields but then that doesn't work with options_from_collection_for_select.

MurifoX · Accepted Answer · 2013-07-29 12:28:33Z

1

You can create a scope for the shared query like this:

scope :shared, where(:status => 'shared')

And then you can chain ActiveRecord methods to your liking:

@subject = Material.select(:subject).where("materials.subject IS NOT NULL 
  AND materials.subject != '' ").shared.uniq

More on scopes here: http://guides.rubyonrails.org/active_record_querying.html#scopes

answered Jul 29, 2013 at 12:28

MurifoX

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1 Comment

Finnjon Over a year ago

Thanks. This works too and the scoping is useful for other things as well.

Scott · Accepted Answer · 2013-07-29 12:49:13Z

1

Try this

@subject = Material.unscoped.select(:subject).where("subject IS NOT NULL and materials.subject != '' and status = 'shared'").uniq

edited Jul 29, 2013 at 12:49

Scott

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answered Jul 29, 2013 at 12:28

Thaha kp

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