使用mongdb，ruby和sinatra如何使用数学和聚合函数？

I have a mongodb collection. Using the ruby driver, the following works:

我有一个mongodb系列。使用ruby驱动程序，以下工作：

search = 'LONDON'
result = posts.find(:district => search).to_a.to_json

and produces the following in the firebug console:

并在firebug控制台中生成以下内容：

[{"_id":"{AB46B6E4-46F7-44F6-8D88-0002C05947BB}","price":"450000","date_sold":"2013-10-23 00:00","post_code":"NW6 2DT","house_type":"F","condition":"N","freehold":"L","house_number":"72","flat_number":"FLAT 3","street":"LOVERIDGE ROAD","town":null,"district":"LONDON","region":"CAMDEN","county":"GREATER LONDON"}]

There are 30 records in the collection, when I change to an aggregate function as follows:

当我更改为聚合函数时，集合中有30条记录，如下所示：

result = posts.find( { :price => { $gt => 100000 } } ).to_a.to_json

I get an empty [ ] in the console. Is this because the data type, in the collection, is not set to integer? If so, how can I change it programatically (i.e. not in the shell)?

我在控制台中得到一个空的[]。这是因为集合中的数据类型未设置为整数吗？如果是这样，我如何以编程方式（即不在shell中）更改它？

Or is the query wrong? I am using the mongodb ruby driver.

或者查询错了？我正在使用mongodb ruby​​驱动程序。

All help gratefully received, thank you.

感谢所有的帮助，谢谢。

1 个解决方案

#1

You are so close - your example needs quotes around $gt, and the value of the price field needs to be integer and not string so that $gt will work as you desire. Here's a test that verifies this. Hope that this helps.

你是如此接近 - 你的例子需要$ gt左右的引号，价格字段的值需要是整数而不是字符串，以便$ gt可以按你的意愿工作。这是一个验证这一点的测试。希望这会有所帮助。

test.rb

test.rb

require 'mongo'
require 'json'
require 'test/unit'

class MyTest < Test::Unit::TestCase
  def setup
    @posts = Mongo::MongoClient.new['test']['posts']
    @docs = JSON.parse <<-EOT
[{"_id":"{AB46B6E4-46F7-44F6-8D88-0002C05947BB}","price":"450000","date_sold":"2013-10-23 00:00","post_code":"NW6 2DT","house_type":"F","condition":"N","freehold":"L","house_number":"72","flat_number":"FLAT 3","street":"LOVERIDGE ROAD","town":null,"district":"LONDON","region":"CAMDEN","county":"GREATER LONDON"}]
    EOT
    @posts.remove
    @posts.insert(@docs)
  end

  test "find examples" do
    result = @posts.find( { :price => { '$gt' => 100000 } } ).to_a
    assert(result.count == 0)
    puts "result from post: #{result.to_json}"

    @docs.each{|doc| doc.delete("_id"); doc["price"] = doc["price"].to_i}
    @posts.insert(@docs)
    result = @posts.find( { :price => { '$gt' => 100000 } } ).to_a
    assert(result.count > 0)
    puts "result after fixes: #{result.to_json}"
  end
end

ruby test.rb

ruby test.rb

Loaded suite test
Started
result from post: []
result after fixes: [{"_id":{"$oid": "5355e4c3a3f57661f3000001"},"price":450000,"date_sold":"2013-10-23 00:00","post_code":"NW6 2DT","house_type":"F","condition":"N","freehold":"L","house_number":"72","flat_number":"FLAT 3","street":"LOVERIDGE ROAD","town":null,"district":"LONDON","region":"CAMDEN","county":"GREATER LONDON"}]
.

Finished in 0.00482 seconds.

1 tests, 2 assertions, 0 failures, 0 errors, 0 pendings, 0 omissions, 0 notifications
100% passed

207.47 tests/s, 414.94 assertions/s