在rails

Question

我在我的rails应用程序中使用saber api（测试许可证），   我得到一个JSON响应，当我解析它时得到这个哈希

{
    "OriginLocation"=>"DEN",
    "Destinations"=>[
    {
    "Rank"=>1,
    "Destination"=>{
    "DestinationLocation"=>"LAX",
    "AirportName"=>"Los Angeles International Airport",
    "CityName"=>"Los Angeles",
    "CountryCode"=>"US",
    "CountryName"=>"United States",
    "RegionName"=>"North America",
    "Type"=>"Airport"
    }
    },
    {
    "Rank"=>2,
    "Destination"=>{
    "DestinationLocation"=>"LAS",
    "AirportName"=>"McCarran International Airport",
    "CityName"=>"Las Vegas",
    "CountryCode"=>"US",
    "CountryName"=>"United States",
    "RegionName"=>"North America",
    "Type"=>"Airport"
    }
    },
    {
    "Rank"=>3,
    "Destination"=>{
    "DestinationLocation"=>"CHI",
    "CountryCode"=>"US",
    "CountryName"=>"United States",
    "RegionName"=>"North America",
    "MetropolitanAreaName"=>"Chicago",
    "Links"=>[
    {
    "rel"=>"airportsInCity",
    "href"=>"https://api.test.sabre.com/v1/lists/supported/cities/CHI/airports"
    }
    ],
    "Type"=>"City"
    }
    } 
    ...
    }

如何从中提取数据（例如：目的地）信息？ 我试过这段代码，但收到错误" undefined method ``each' for nil:NilClass "

@hash['Destinations'].each do |key, value|
  puts key
  value.each do |k,v|
    puts k
    puts v
  end
end

Answer 1

即使您已指定key和value，也只会填充key（包含整个哈希数据），value为nil }。这就是您收到错误的原因。

假设您使用的是Ruby 2.3或更高版本，我建议您使用类似的内容：

@hash['Destinations'].map { |d| d.dig('Destination', 'CityName') }
#=> ["Los Angeles", "Las Vegas", nil]

您可以在dig阅读更多内容。它对于这种深层嵌套的数据非常有用，它可以保护您免受不存在的密钥的影响（并返回nil）;只要你不在数组和哈希上混用它。