undefined method `to_f' for #<ActiveRecord::Relation:0x472d0a0>

Question

I'm trying to build a call tracking app as a way to learn rails and twilio. Right now, what I'd like to do is to make a graph that shows the number of phone calls a particular phone gets every day.

The way my data structure is set up, is that the phone model has_many calls.

In my Phone Model, I have

def total_on(date)
  self.calls.where("placed_at >= ? AND placed_at <= ?", date.beginning_of_day, date.end_of_day)
end

In my view, I have the following javascript :

<script type="text/javascript" charset="utf-8">
  $(function () {
    new Highcharts.Chart({
      chart: { renderTo: 'calls_chart' },
      title: { text: 'Calls Per Day' },
      xAxis: { type: 'datetime' },
      yAxis: {
        title: { text: ' Calls'}
      },
      series: [{
        name: "<%= @phone.name %>",
        pointInterval: <%= 6.days * 1000 %>,
        pointStart: <%= 1.month.ago.at_midnight.to_i * 1000 %>,
        data: <%= (1.month.ago.to_date..Date.today).map { |date| @phone.total_on(date).to_f}.inspect %>
      }]
    });
  });

The important part is the data:

<%= (1.month.ago.to_date..Date.today).map { |date| @phone.total_on(date).to_f}.inspect %>

when I try to place the data for calls on each day, I get the error

undefined method `to_f' for #<ActiveRecord::Relation:0x472d0a0>

I'm not really sure if I'm doing anything right here, to be honest. A fellow stackoverflower helped me make the Instance Method I referenced above, so I'm assuming that's a lot better than what I wrote.

So, what would I need to change to make it so that I can call the number of phone calls made on a particular date, in the view?

UPDATE

After Zack's answer, I now get the error

SQLite3::SQLException: no such column: calls.placed_at: SELECT COUNT(*) FROM "calls"  WHERE "calls"."phone_id" = 44 AND ("calls"."placed_at" BETWEEN '2012-09-11 00:00:00.000000' AND '2012-09-11 23:59:59.999999')

Probably I'm confusing the associations I have or something. Here are the models with the data structure, if they help --

Phone Model

# == Schema Information
#
# Table name: phones
#
#  id              :integer          not null, primary key
#  name            :string(255)
#  twilio_number   :integer
#  original_number :integer
#  user_id         :integer
#  created_at      :datetime         not null
#  updated_at      :datetime         not null
#

class Phone < ActiveRecord::Base

  attr_accessible :original_number, :user_id, :name, :twilio_number
  belongs_to :user
  has_many :calls, dependent: :destroy

  validates :name, presence: true
  validates :twilio_number, presence: true
  validates :original_number, presence: true
  validates :user_id, presence: true

  default_scope order: 'phones.created_at DESC'

  validate :check_phone_limit, :on => :create

  def check_phone_limit
    if User.find(self.user_id).at_max_phone_limit?
      self.errors[:base] << "Cannot add any more phones"
    end
  end

  def original_number=(value)
    num = value.to_s.gsub(/[^0-9+]/, "")
    write_attribute(:original_number, num.to_i)
  end

def total_on(date)
  self.calls.where(placed_at: date.beginning_of_day..date.end_of_day).count
end

end

Call Model

# == Schema Information
#
# Table name: calls
#
#  id               :integer          not null, primary key
#  AccountSid       :string(255)
#  From             :string(255)
#  To               :string(255)
#  CallStatus       :string(255)
#  ApiVersion       :string(255)
#  Direction        :string(255)
#  FromCity         :string(255)
#  FromState        :string(255)
#  FromZip          :string(255)
#  FromCountry      :string(255)
#  ToCity           :string(255)
#  ToState          :string(255)
#  ToZip            :string(255)
#  ToCountry        :string(255)
#  CallSid          :string(255)
#  DialCallSid      :string(255)
#  DialCallDuration :string(255)
#  DialCallStatus   :string(255)
#  RecordingUrl     :string(255)
#  phone_id         :integer
#  DialCallMinutes  :integer
#  created_at       :datetime
#  updated_at       :datetime
#

class Call < ActiveRecord::Base
  attr_accessible :AccountSid, :From, :To, :CallStatus, :ApiVersion, :Direction, :FromCity, :FromState, :FromZip, :FromCountry, :ToCity, :ToState, :ToZip, :ToCountry, :CallSid, :DialCallSid, :DialCallDuration, :DialCallStatus, :RecordingUrl, :DialCallMinutes
  belongs_to :phone


  def self.create_from_incoming_call(params)

   user_phone = Phone.find_by_twilio_number(params['To']) #Finds the phone number in the database based on what phone Twilio is calling

    twilio_request_params = {
      :CallSid => params['CallSid'],
      :AccountSid => params['AccountSid'],
      :From => params['From'],
      :To => params['To'],
      :CallStatus => params['CallStatus'],
      :ApiVersion => params['ApiVersion'],
      :Direction => params['Direction'],
        :FromCity => params['FromCity'],
        :FromState => params['FromState'],
      :FromZip => params['FromZip'],
      :FromCountry => params['FromCountry'],
      :ToCity => params['ToCity'],
      :ToState => params['ToState'],
      :ToZip => params['ToZip'],
      :ToCountry => params['ToCountry']


    }

    call = Call.new(twilio_request_params)
    call.save  
    return call

  end

  def Call.update_dial_call(params)

    twilio_request_params = {
        :DialCallSid => params['DialCallSid'],
        :DialCallDuration => params['DialCallDuration'],
        :DialCallStatus => params['DialCallStatus'],
        :RecordingUrl => params['RecordingUrl'],
      :DialCallMinutes => (params['DialCallDuration'].to_f/60.to_f).ceil
    }

    call = Call.where( :CallSid => params['CallSid'] ).first
    call.update_attributes twilio_request_params
    call.save

  end


end

Phone Show Action

  def show
  @user = current_user
  @phone = Phone.find_by_id(params[:id])
  @calls = @phone.calls.paginate(page: params[:page])
  end

And, the javascript in the view ( repeated for easier reading)

<script type="text/javascript" charset="utf-8">
  $(function () {
    new Highcharts.Chart({
      chart: { renderTo: 'calls_chart' },
      title: { text: 'Calls Per Day' },
      xAxis: { type: 'datetime' },
      yAxis: {
        title: { text: ' Calls'}
      },
      series: [{
        name: "<%= @phone.name %>",
        pointInterval: <%= 6.days * 1000 %>,
        pointStart: <%= 1.month.ago.at_midnight.to_i * 1000 %>,
        data: <%= (1.month.ago.to_date..Date.today).map { |date| @phone.total_on(date).to_f}.inspect %>
      }]
    });
  });
</script

>

Answer 1

Your total_on method is returning an association, not a number.

Try appending .count:

def total_on(date)
  calls.where("placed_at >= ? AND placed_at <= ?", date.beginning_of_day, date.end_of_day).count
end

You can also give it a date range to shorten the method a bit (effectively the same, but easier to read):

def total_on(date)
  calls.where(placed_at: date.beginning_of_day..date.end_of_day).count
end

Update:

Did the original "placed_at" query ever work, or was it never actually called because of the NoMethodError?

It doesn't look like there is a placed_at column in your model, but I assume you can used created_at just as well.

If you want to used placed_at, you could define this method (I changed the name to placed_on for style):

class Call < ActiveRecord::Base

  def self.placed_on(date)
    where(created_at: date.beginning_of_day..date.end_of_day)
  end

end

You can chain this into your total_on method:

class Phone < ActiveRecord::Base

  def total_on(date)
    calls.placed_on(date).count
  end

end