Create a method that changes attribute (integer) rails

Question

I have an integer in my Parent Object's table called completion_status with a default value of 0. Id like to set this to the same value as "@parent.child.count('completion', :distinct => true)", but I have no idea how to do this in the controller, or even if the controller is the best place to do this.

I know there's not much information included here, but let me know if I'm missing something important. I'm having kind of a brain-fart moment here.

EDIT: Just tried:

def set_completion 
   @app = App.find(params[:id]) 
   @app.update_attribute(:completion_status => @app.elements.count('completion', :distinct => true))
end

Set the value using that line and save it. There are a number of ways to do it, including that, using update_attribute, etc. — Dave Newton
– Dave Newton, Commented Jun 23, 2015 at 23:38
@DaveNewton I just tried out update_attribute but I get a wrong number of arguments (1 for 2) error. Check the edit. — foxtrotuniform6969
– foxtrotuniform6969, Commented Jun 23, 2015 at 23:49
Well, that's not how update_attribute works. Do you have access to any documentation, either locally (even ri) or on the Web? E.g., apidock.com/rails/ActiveRecord/Base/update_attribute — Dave Newton
– Dave Newton, Commented Jun 23, 2015 at 23:51
update_attribute expects 2 arguments: the name of the attribute and the vale you're updating it to eg: update_attribute(:quantity, 42) (which differs from update_attributes which takes name/value pairs as a hash) — Taryn East
– Taryn East, Commented Jun 23, 2015 at 23:52
@TarynEast I was using a hashrocket instead of a comma for some ungodly reason. Thank you for bringing me back to my senses. Now I only have to factor in the Child's Children's attribute as well and figure out how the hell I'm going to do this. — foxtrotuniform6969
– foxtrotuniform6969, Commented Jun 23, 2015 at 23:56

Ahmad Al-kheat · Accepted Answer · 2015-06-23 23:46:38Z

2

From what I understand, this value could possibly change everytime you create a new child, because creating a new child will change the value of @parent.child.count, so you want to reset completion_status everytime you create or update a new child, so one way to do this is inside the create and update action of the ChildrenController -assuming you have one :

def create 
  @parent = Parent.find(params[:parent_id]
  @child = @parent.children.build(child_params)
  if @child.save
    @parent.completion_status = @parent.children.count // this is the line to add
  end
end

This code could be improved in different ways but I'm just giving you an example.

answered Jun 23, 2015 at 23:46

Ahmad Al-kheat

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7 Comments

foxtrotuniform6969 Over a year ago

@AhmadAk-kheat I'll go ahead and see if I can adapt this for my use and I'll let you know. completion_status should only update when a Child is edited to change the boolean attribute of it from true to false (hence the ('completion', :distinct => true)). However, you are indeed right.

foxtrotuniform6969 Over a year ago

@AhmadAk-kheat Any idea how I'd count the Child's Children with true? When I try to I get an undefined method 'child's child'

Ahmad Al-kheat Over a year ago

@Nickdb93 why do you need to count the child's children? I thought a parent has multiple children not a child has multiple children.

foxtrotuniform6969 Over a year ago

An App (parent) has multiple Elements (child), each of which has multiple Features (child's children). Ultimately, I'd like completion status to equal ( Total Elements / Elements Completed ) + ( Total Features / Features Completed ). The end goal being to have a generally useful (though not mathematically exact) percentage that can be used in a progress bar.

Ahmad Al-kheat Over a year ago

@Nickdb93 Ok you can say this : @element.features.where(completed: true).count

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