使用Mongoid按日期分组的最佳方式
我正在尝试使用不同的格式（日，月，年）按日期进行查询分组，我知道这对于典型的SQL数据库来说是一个简单的查询。
您可以在此链接上看到代码： https ： //gist.github.com/jrdi/b3f824fa4e7531c43bfd
知道我可以跑：
> Patient.group_by('created_at', 'day') => [{"_id":"11/10/2013","value":{"count":3.0}}] 在我看来，所有这些代码组成一个简单的组是非常奇怪的。 我错过了重要的事吗？
PD：我知道方法self.map和一些插值不是最好的方法，但知道我关心Mongo的东西。
这是一个使用聚合框架按日期分组的答案。 我希望你喜欢它。
应用程序/模型/ patient.rb
class Patient include Mongoid::Document field :name, type: String def self.group_by(field, format = 'day') key_op = [['year', '$year'], ['month', '$month'], ['day', '$dayOfMonth']] key_op = key_op.take(1 + key_op.find_index { |key, op| format == key }) project_date_fields = Hash[*key_op.collect { |key, op| [key, {op => "$#{field}"}] }.flatten] group_id_fields = Hash[*key_op.collect { |key, op| [key, "$#{key}"] }.flatten] pipeline = [ {"$project" => {"name" => 1, field => 1}.merge(project_date_fields)}, {"$group" => {"_id" => group_id_fields, "count" => {"$sum" => 1}}}, {"$sort" => {"count" => -1}} ] collection.aggregate(pipeline) end end
测试/单元/ patient_test.rb
require 'test_helper' require 'pp' class PatientTest < ActiveSupport::TestCase def setup Patient.delete_all end test "group by date" do [ {"name" => "John", "created_at" => Date.new(2012, 10, 10).mongoize}, {"name" => "Jane", "created_at" => Date.new(2012, 10, 31).mongoize}, {"name" => "Mary", "created_at" => Date.new(2012, 10, 31).mongoize}, {"name" => "Mark", "created_at" => Date.new(2012, 12, 12).mongoize}, {"name" => "Alex", "created_at" => Date.new(2013, 11, 10).mongoize}, {"name" => "Andy", "created_at" => Date.new(2013, 10, 31).mongoize}, {"name" => "Toni", "created_at" => Date.new(2013, 10, 31).mongoize}, {"name" => "Cori", "created_at" => Date.new(2013, 11, 10).mongoize} ].each do |patient| Patient.create(patient) end puts "\nMongoid::VERSION:#{Mongoid::VERSION}\nMoped::VERSION:#{Moped::VERSION}" pp Patient.group_by('created_at', 'month') end end
$ rake test
Run options: # Running tests: [1/1] PatientTest#test_group_by_date Mongoid::VERSION:3.1.5 Moped::VERSION:1.5.1 [{"_id"=>{"year"=>2012, "month"=>10}, "count"=>3}, {"_id"=>{"year"=>2013, "month"=>10}, "count"=>2}, {"_id"=>{"year"=>2013, "month"=>11}, "count"=>2}, {"_id"=>{"year"=>2012, "month"=>12}, "count"=>1}] Finished tests in 0.042561s, 23.4957 tests/s, 0.0000 assertions/s. 1 tests, 0 assertions, 0 failures, 0 errors, 0 skips