How would I check if a value is found in an array of values

Question

I want to perform an if condition where, if linkedpub.LPU_ID is found in an array of values(@associated_linked_pub), do some action.

I tried the following but the syntax is not correct.

Any suggestion is most welcomed..Thanks a lot

<% for linkedpub in Linkedpub.find(:all) %>
   <% if linkedpub.LPU_ID IN @associated_linked_pub  %>
       # do action
   <%end%>
<%end%>

possible duplicate of [check if value exists in array in Ruby](http://stackoverflow.com/questions/1986386/check-if-value-exists-in-array-in-ruby) — Mat, Jun 14 '11 at 21:01

Jits · Accepted Answer · 2011-06-14T21:04:44.613

You can use Array#include?

So...

if @associated_linked_pub.include? linkedpub.LPU_ID
  ...

Edit:

If @associated_linked_pub is a list of ActiveRecord objects then try this instead:

if @associated_linked_pub.map{|a| a.id}.include? linkedpub.LPU_ID
  ...

Edit:

Looking at your question in more detail, it looks like what you are doing is VERY inefficient and unscalable. Instead you could do...

For Rails 3.0:

Linkedpub.where(:id => @associated_linked_pub)

For Rails 2.x:

LinkedPub.find(:all, :conditions => { :id => @associated_linked_pub })

Rails will automatically create a SQL IN query such as:

SELECT * FROM linkedpubs WHERE id IN (34, 6, 2, 67, 8)

score 3 · Answer 2 · answered Feb 10 '14 at 03:04

3

linkedpub.LPU_ID.in?(@associated_linked_pub.collect(&:id))

Using in? in these cases has always felt more natural to me.

answered Feb 10 '14 at 03:04

bigtex777

score 1 · Answer 3 · edited Jun 15 '11 at 01:01

1

@associated_linked_pub.collect(&:id).include?(linkedpub.LPU_ID)

edited Jun 15 '11 at 01:01

Ken Bloom

answered Jun 14 '11 at 20:59

Sameer C

score 1 · Answer 4 · answered Jun 14 '11 at 20:59

1

if @associated_linked_pub is an array, try

if @associated_linked_pub.include?(linkedpub.LPU_ID)

answered Jun 14 '11 at 20:59

John Bachir

4 Answers4