CODEWITHSUNDEEP
ruby-on-railsrubyconditional-statements
Rubioli
Rubioli

Reputation: 680

Ruby on Rail - Check if at least 2 records with my condition exsist

In my application, I want to show db records only if 2 records with my/same conditions exists?

What is the most efficient way of checking it?

Here is my code:

- if @users.where(friend_group: 0).where(city_id: 2).any?
  - @users.where(user_group: 0).where(city_id: 2).each do |user|
    %p= user.name
    %p= user.city.name

Instead of any?, I want to check if when only 2 records with same conditions exist, it can show them.

I have tried - if @users.where(friend_group: 0).where(city_id: 2).exist?(2), with no luck.

ps: I am using rails 4.2

Upvotes: 0

Views: 160

Answers (2)

max
max

Reputation: 101811

Generally you should avoid doing database queries in the view - A better solution is to do it in the controller or in the model:

class User < ActiveRecord::Base
  # ...
  def self.by_group_and_city(friend_group, city, threshold: 2)
    scope = User.where(friend_group: friend_group, city: city)
    # if you want only if exactly two records match then use ==
    scope.size >= threshold ? scope : User.none
  end
end

We return User.none instead of nil if there are no matching records - that way you can safely call methods like .each on the empty relation object.

- User.by_group_and_city(0, 2).each do |u|
  %p= user.name
  %p= user.city.name

Better yet would be let the controller do the querying:

def index
  @nearby_users = User.by_group_and_city(0, 2)
  # ...
end

- @nearby_users.each do |u|
  %p= user.name
  %p= user.city.name

Upvotes: 2

Малъ Скрылевъ
Малъ Скрылевъ

Reputation: 16507

Just use active record relation's #count, and range indexation as follows:

- rela = @users.where(friend_group: 0).where(city_id: 2)
- if rela.count > 1
  - rela[0..1].each do |user|
    %p= user.name
    %p= user.city.name

Upvotes: 0

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