Iterate over Array of Objects and Return Attributes

Question

I am trying to return a list of titles of objects in Rails, however I keep getting the entire object returned instead of the title attribute.

loe is the object which has an attribute which is a list of articles (named article), each article is itself an object with an attribute called title.

<%= loe.article.each { |x| print x.title } %>

is how I am currently attempting to do the iteration, but this returns the entire list of articles.

Solution 1

Use Array#map to invoke the title method on each and create a new array with the results:

loe.article.map(&:title)

The above is shorthand for

loe.article.map{ |o| o.title }

Solution 2

Using the ERB tag like '<%= ' means that you're asking ERB to display the result of that expression (above and beyond the fact that you're calling print inside the block). And a call to an Enumerable method like each will return the original array, which is what you're seeing.

Change the tag to <% (remove the =) and you should be good to go.

Solution 3

loe.article.map {|x| x.title} perhaps?

Solution 4

class LOE < ActiveRecord::Base
  has_many :articles
end

class Article < ActiveRecord::Base
  belongs_to :loe
end

loe.articles.select(:title).collect{|a| a.title}

map and collect are aliases, and you can call select(:fieldname) on an AREL to return just that field. You still get objects, but they're read-only and are populated with whatever the select returned, so to get the array of titles you need to do the collect.

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Comments

[Andrey Deineko]

the only answer to question