Ruby：根据标准从深度嵌套的JSON结构中提取元素 [英] Ruby: Extract elements from deeply nested JSON structure based on criteria

问题描述

想要从每个有 marketName =='Moneyline'的市场提取每个 marketID 。尝试了 .map s， .reject s和/或 .select s但无法缩小，因为复杂的结构令我困惑。

Want to extract every marketID from every market that has a marketName == 'Moneyline'. Tried a few combinations of .maps, .rejects, and/or .selects but can't narrow it down as the complicated structure is confusing me.

有很多 code>在事件中，并且还有许多事件。结构样本（为简洁起见，试图对其进行编辑）：



There are many markets in events, and there are many events as well. A sample of the structure (tried to edit it for brevity):

{"currencyCode"=>"GBP",
"eventTypes"=>[
    {"eventTypeId"=>6423,
    "eventNodes"=>[
        {"eventId"=>28017227,
        "event"=>
            {"eventName"=>"Philadelphia @ Seattle"
            },
            "marketNodes"=>[
                {"marketId"=>"1.128274650",
                "description"=>
                    {"marketName"=>"Moneyline"}
                },
                {"marketId"=>"1.128274625",
                "description"=>
                    {"marketName"=>"Winning Margin"}
                }}}]},
        {"eventId"=>28018251,
        "event"=>
            {"eventName"=>"Arkansas @ Mississippi State"
            },
            "marketNodes"=>[
                {"marketId"=>"1.128299882",
                "description"=>
                    {"marketName"=>"Under/Over 60.5pts"}
                },
                {"marketId"=>"1.128299881",
                "description"=>
                    {"marketName"=>"Moneyline"}
                }}}]},
        {"eventId"=> etc....

试过各种各样的东西，例如，

Tried all kinds of things, for example,

markets = json["eventTypes"].first["eventNodes"].map {|e| e["marketNodes"].map { |e| e["marketId"] } if (e["marketNodes"].map {|e| e["marketName"] == 'Moneyline'})}
markets.flatten
# => yields every marketId not every marketId with marketName of 'Moneyline'

获取Moneyline中每个marketId的简单数组没有其他信息的市场就足够了。如果喜欢，使用Rails方法也可以。

Getting a simple array with every marketId from Moneyline markets with no other information is sufficient. Using Rails methods is fine too if preferred.

对不起，如果我的编辑搞砸了语法。 这里是来源。在解析JSON之后，它看起来像只有 => 而不是：。

Sorry if my editing messed up the syntax. Here's the source. It looks like this only with => instead of : after parsing the JSON.

谢谢！

推荐答案

我喜欢嵌套地图并选择：D

I love nested maps and selects :D

require 'json'

hash = JSON.parse(File.read('data.json'))

moneyline_market_ids = hash["eventTypes"].map{|type|
  type["eventNodes"].map{|node|
    node["marketNodes"].select{|market|
      market["description"]["marketName"] == 'Moneyline'
    }.map{|market| market["marketId"]}
  }
}.flatten

puts moneyline_market_ids.join(', ')
#=> 1.128255531, 1.128272164, 1.128255516, 1.128272159, 1.128278718, 1.128272176, 1.128272174, 1.128272169, 1.128272148, 1.128272146, 1.128255464, 1.128255448, 1.128272157, 1.128272155, 1.128255499, 1.128272153, 1.128255484, 1.128272150, 1.128255748, 1.128272185, 1.128278720, 1.128272183, 1.128272178, 1.128255729, 1.128360712, 1.128255371, 1.128255433, 1.128255418, 1.128255403, 1.128255387

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