How validate before save with object from new action

Question

Im trying to create a new alert only if is covered returns true, how can I access the object from new to check if it is covered or not, and if it is save correctly if not respond with the errors. My error is NameError (undefined local variable or method `params' for #):

  class Alert < ActiveRecord::Base
    belongs_to :user
    has_many :activities

    scope :by_year, lambda { |year| where('extract(year from created_at) = ?', year) }
    validate :is_covered, :before => :create

    def is_covered

        @schools = School.all

    @schools.each do |school|

            distance = triangulate(school.latitude, school.longitude, self.latitude, self.longitude)

      if distance < school.radius.to_f  
        self.school_id = school.id
        return self
      else
        self.errors.add(:latitude,"Sorry You Arent Within a School")
        return self
      end
    end
    end
    def power(num, pow)
        num ** pow
  end
    def triangulate(lat1, lng1, lat2, lng2)

    dtor = Math::PI/180
    r = 6378.14*1000

        rlat1 = lat1.to_f * dtor 
    rlong1 = lng1.to_f * dtor 
    rlat2 = lat2.to_f * dtor 
    rlong2 = lng2.to_f * dtor
    dlon = rlong1 - rlong2
    dlat = rlat1 - rlat2 

        a = power(Math::sin(dlat/2), 2) + Math::cos(rlat1) * Math::cos(rlat2) * power(Math::sin(dlon/2), 2)
        c = 2 * Math::atan2(Math::sqrt(a), Math::sqrt(1-a))

        distance = r * c

    return distance
  end
end

Controller

   def create
        @alert = Alert.create(alert_params).is_covered
        @alert.status = "active"

        respond_to do |format|
            if @alert.save && @alert.valid?
              log_activity(nil, "has created alert", @alert.id, @alert.school_id, "Alert")
              format.json { render json: @alert.id}
            else
              format.json { render json: @alert.errors, status: :unprocessable_entity }
            end
        end
      end

neo · Accepted Answer · 2015-06-16 03:26:51Z

2

You can call the method in your create action in your controller, it should look something like:

def create
  if Alert.new.is_covered?
    #... Do some stuff
  end
end

Also given that you're not passing any argument from your controller to the Alert Class and then to that method, it probably won't do what you're trying to do, but that's another issue.

I assumed your question is more along the lines of how to access that method from the controller.

edited Jun 16, 2015 at 3:26

answered Jun 16, 2015 at 3:19

neo

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5 Comments

user3882976 Over a year ago

if i do use that how can i get the alert object

neo Over a year ago

Yes you can use self inside the method. But you can exclude the self. For example: if you wanted activities you'd call self.activities, that's the same as calling activities.

user3882976 Over a year ago

NameError (undefined local variable or method `params' for #<Alert:0x007fe5993593d8>): thats what i get

neo Over a year ago

I don't see the changes you made to your Alert class.

neo Over a year ago

it should be something like that...

def create   if Alert.new.is_covered?     @alert = Alert.create(alert_params)    #... remaining of the method goes here   end

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