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copied!<p>The usual advice is to move logic to the model and keep the controller as lean as possible. There are different approaches for the filter method, the first one:</p> <pre><code>class Record < ActiveRecord::Base def self.filter(attributes) attributes.select { |k, v| v.present? }.reduce(all) do |scope, (key, value)| case key.to_sym when :id, :zip # direct search scope.where(key => value) when :city, :state # regexp search scope.where(["#{key} ILIKE ?", "%#{value}%"]) when :order # order=field-(ASC|DESC) attribute, order = value.split("-") scope.order("#{self.table_name}.#{attribute} #{order}") else # unknown key (do nothing or raise error, as you prefer to) scope end end end end </code></pre> <p>A second approach, write a bare <code>filter</code> that only uses existing scopes:</p> <pre><code>class Record < ActiveRecord::Base SUPPORTED_FILTERS = [:id, :city, ...] scope :id, ->(value) { where(id: value) } scope :city, ->(value) { where(city: "%#{value}%") } ... def self.filter(attributes) attributes.slice(*SUPPORTED_FILTERS).reduce(all) do |scope, (key, value)| value.present? ? scope.send(key, value) : scope end end end </code></pre> <p>For Rails 5, which now uses ActionController::Parameters, the syntax for the filter method is:</p> <pre><code>def self.filter(attributes) attributes.permit(SUPPORTED_FILTERS).to_hash.reduce(all) do |scope, (key, value)| value.present? ? scope.send(key, value) : scope end end </code></pre> <p>Models can be called from anywhere in your app, so they are re-usable and easier to test. Now the controller looks as simple as:</p> <pre><code>class RecordsController < ApplicationController::Base respond_to :html, :xml def index @records = Record.filter(params) end end </code></pre>

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