How to build a multi-dimensional array with ruby on rails

Question

I have a model Messages w the fields: id, message, read, view_count. View count is calculated from another table, it's not in the message model

What I want to do is loop over all the Messages and track all unreads (read = false) and the view count per the unreads to output something like this:

1, "message stuff", false, 14
2, "message stuff", false, 31
3, "message stuff", false, 1

While looping through messages like so:

Messages.each do |m|
end

In the loop, how can I build an array that captures the message.id and the view_count. And then how can I output the final result?

Thank you

you said view_count is calculated from another table, is this column only a counter_cache? or do you also need to calculate this inside the block? — jvnill
– jvnill, Commented Mar 14, 2013 at 3:11
yeah is there a relationship between the two? like Messages.views? — j_mcnally
– j_mcnally, Commented Mar 14, 2013 at 3:11

user2040486 · Accepted Answer · 2013-03-14 04:17:10Z

3

mes_fields = Array.new
messages = Array.new
mess = Messages.where("read = ?", false)


mess.each_with_index do |m_row, index|
    m_row.each do |m|
        mes_fields.push(m)
    end
    messages.push(mes_fields[index])
end

Then message would look like

[[1, "message stuff", false, 14],
 [2, "message stuff", false, 31],
 [3, "message stuff", false, 1]]

edited Mar 14, 2013 at 4:17

answered Mar 14, 2013 at 3:38

user2040486

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j_mcnally · Accepted Answer · 2013-03-14 03:24:21Z

3

can i recommend a hash instead?

message_hash = {}

Messages.where(:read => false).each do |m|
  messages_hash[m.id] = m.view_count
end

puts messages_hash

assuming

class Messages
  def view_count
    #some view_count calculation code.
  end
end

untested but that should be close.

outputs

{
  11 => 33,
  12 => 11,
  13 => 34,
}

edited Mar 14, 2013 at 3:24

answered Mar 14, 2013 at 3:05

j_mcnally

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2 Comments

jvnill Over a year ago

hmm this doesn't make any sense. m.id will be unique so the hash will always have values = 1. am i missing something?

j_mcnally Over a year ago

the question was vague in that regaurd, we talk about a rollup on read count but i dont know what we've rolling up to?

Harish Shetty · Accepted Answer · 2013-03-14 03:30:56Z

0

Try this:

Message.where(:read => false).map{ |m| [m.id, m.view_count]}
# => [ [ 1, 14], [ 2, 31], [ 3, 1]]

answered Mar 14, 2013 at 3:30

Harish Shetty

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