Loop Through Activerecord::Associations::Collectionproxy with Each

Loop through ActiveRecord::Associations::CollectionProxy with each

You probably want to use map instead:

page.content.map do |item|
  item.content_id
end

map (aka collect) will iterate through an array and run whatever code you ask it to on the members of the array, one by one. It will return a new array containing the return values for those method calls.

Can't loop through an ActiveRecord_Associations_CollectionProxy object on controller's destroy action?

my understanding you can use callback in your models

open your role model app/models/role.rb

class Role < ApplicationRecord
  # callback
    before_destroy :check_rules

  # here is the callback method that will run automatically before destroy
  def check_rules
    puts self # in model your @role is equal to self
    self.rules.map do |rule|
      puts rule
      # other action
    end
  end
end

Rails loop through ActiveRecord::Associations:CollectionProxy

You can do this completely in SQL/ActiveRecord. The query you want to run ultimately is

SELECT article_id, min(date), sum(views)
FROM   daily_value_metrics -- Or whatever your table is called
GROUP BY article_id

You can run this with ActiveRecord with the following:

table = DailyValueMetric.arel_table
results = DailyValueMetric.select(table[:article_id], 
  table[:date].minimum.as('date'), 
  table[:views].sum.as('views')).group(:article_id).to_a
# Calling to_a so I can call first for the example
results.first.date #=> date
results.first.views #=> views
results.first.article_id #=> Id

The records will look like

[#<DailyViewMetric id: nil, article_id: 1089536>, ...]

Because the SQL query does not return an id column in the result set. This is because of the way that ActiveRecord::Base#inspect shows the columns defined on the table, and not the returned values outside of the table columns. Views and Date will not necessarily be shown, unless there is a column with the same name, but if you call those attributes on the model instance, you will be able to get the value

Rails 4: Looping through association

According to your code there are no multiple instances of academic related to the given member (it's defined using has_one relation).

The answer is: you cannot loop them.

The correct code for your view should be:

<% if @member.academic.present? %>
 <% fields_academic = [:major, :second_major, :minor, :second_minor] %>
  <h1>Academics</h1>
  <%= render 'database/shared/display', model_obj: @memeber.academic, data: academic, fields: fields_academic %>
 <% end %>
<% end %>

If your intention was to have many academics for a memeber, then use has_many instead.

class Member
  has_many :academics
end

Querying an Associations::CollectionProxy

ActiveRecord::Associations::CollectionProxy.find method uses the same rules as ActiveRecord::Base.find which is used to retrieve a database row by ID.

So, my_association_collection.find_by(id: 2) or my_association_collection.find(2) will always execute a SELECT query on the database, not reference the existing result.

See doc

Rails method on ActiveRecord::Associations::CollectionProxy

I found out how. Using a self method then all:

def self.format
  all.each do |item|
    # Manipulate items here
  end
end

However, I ended up having a method like this:

def format
  {
    id: id,
    note: 'Contact Note',
    # Etc
  }
end

Then just used:

customer.notes.map {|i| i.format }

RSpec has_many through #ActiveRecord::Associations::CollectionProxy on after_save

The problem is that the aliases are not yet persisted and pluck does a database query (see when you inspect address_aliases, the record does not have an ID yet, it's on memory, it's not on the database yet).

Replace that pluck with map(&:alias_for_city) so it doesn't do a database query and uses the already loaded collection.

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