Ruby on Rails undefined method `delete_at' for "John":String

I am trying to replace an array of names for a column of names out of a database. I am new to Ruby on rails so it could be something simple.

This works fine:

<% students = %w(John Paul Ringo George) %>
<% teams = RoundRobinTournament.schedule(students) %>
<td><%= teams %></td>

This i get an error:

<% @players.each do |player| %>
<% students = player.first_name %>
<% teams = RoundRobinTournament.schedule(students) %>
<td><%= teams %></td>

Error:

undefined method `delete_at' for "John":String
Did you mean?  delete
               delete!

In the RoundRobinModule the "delete_at" what causes the error:

require 'round_robin_tournament/version'

module RoundRobinTournament
   def self.schedule(array)
     array.push(nil) if array.size.odd?
     n = array.size
     1.step(n / 2, 1).each do |i|
       array.insert(n - i, array.delete_at(i))
     end
     pivot = array.pop
     games = (n - 1).times.map do
       day = [[array.first, pivot]] + (1...(n / 2)).map { |j| [array[j], array[n - 1 - j]] }
       array.rotate!
       day
     end
     array.push pivot unless pivot.nil?
     games
  end
 end

Solution

students is supposed to be an array, yet students = player.first_name makes it a string.

I don't know if this is want you want, but the following should work:

<% students = @players.pluck(:first_name) %> # or @players.map(&:first_name)
<% teams = RoundRobinTournament.schedule(students) %>
<td><%= teams %></td>

Use .pluck if @players holds an ActiveRecord::Relation or .map if it's an array of Player objects.

But, the error tells you exactly what & where the problem is. You just need to pay attention. The code would have crashed earlier but both String and Array respond to .size.