Question

我的JSON数组的结构如下：

{"data":[{"Chris":[{"long":10,"lat":19}]},{"Scott":[{"long":9,"lat":18}]}]}

在ruby程序中，我希望能够编辑名称的lat和long值。但我不太清楚该怎么做。

sections.each do |user_coords|
        user_coords.each do |user, coords|
            if user == Usrname then
                #Change lat and long value for Usrname
            end
        end
end

如何做到这一点？

Answer 1

这是访问JSON中的各个元素的方法：

require 'json'

foo = JSON['{"data":[{"Chris":[{"long":10,"lat":19}]},{"Scott":[{"long":9,"lat":18}]}]}']
foo['data'][0]['Chris'][0]['long'] = 5
foo['data'][0]['Chris'][0]['lat'] = 7
foo # => {"data"=>[{"Chris"=>[{"long"=>5, "lat"=>7}]}, {"Scott"=>[{"long"=>9, "lat"=>18}]}]}

通过将变量用作对象的占位符，可以稍微简化路径：

foo = JSON['{"data":[{"Chris":[{"long":10,"lat":19}]},{"Scott":[{"long":9,"lat":18}]}]}']
chris = foo['data'][0]['Chris'][0]
chris['long'] = 5
chris['lat'] = 7
foo # => {"data"=>[{"Chris"=>[{"long"=>5, "lat"=>7}]}, {"Scott"=>[{"long"=>9, "lat"=>18}]}]}

chris指向“Chris”哈希，它嵌入在foo哈希中。对chris散列的更改发生在foo内。

如果哈希是正常定义的，它会更干净/清晰和直接：

foo = JSON['{"data":{"Chris":{"long":5,"lat":7},"Scott":{"long":9,"lat":18}}}']
foo['data']['Chris']['long'] = 5
foo['data']['Chris']['lat'] = 7
foo # => {"data"=>{"Chris"=>{"long"=>5, "lat"=>7}, "Scott"=>{"long"=>9, "lat"=>18}}}

foo更明确地定义为：

foo = {
  'data' => {
    'Chris' => {'long' => 5, 'lat' => 7},
    'Scott' => {'long' => 9, 'lat' => 18}
  }
}

有条件地遍历散列以查找特定的键/值对，使用您的散列：

require 'json'

foo = JSON['{"data":[{"Chris":[{"long":10,"lat":19}]},{"Scott":[{"long":9,"lat":18}]}]}']

user_name = 'Chris'
data = foo['data'].first
data.first.each do |key, value|
  if key == user_name
    data[user_name].first['long'] = 5
    data[user_name].first['lat'] = 6
  end
end

foo # => {"data"=>[{"Chris"=>[{"long"=>5, "lat"=>6}]}, {"Scott"=>[{"long"=>9, "lat"=>18}]}]}

必须使用first（或[0]）来获取哈希元素才能闻到它。

使用正确定义的哈希会产生如下代码：

foo = JSON['{"data":{"Chris":{"long":10,"lat":19},"Scott":{"long":9,"lat":18}}}']
foo['data'].each do |key, value| 
  if key == user_name
    value['long'] = 5
    value['lat'] = 7
  end
end
foo # => {"data"=>{"Chris"=>{"long"=>5, "lat"=>7}, "Scott"=>{"long"=>9, "lat"=>18}}}

如何添加另一个名为Bob且long = 10且lat = 20
的人

听起来你并没有很好地掌握操纵/访问哈希，或者如何转换为/来自JSON。你最好把这些基础知识搞定。

不要以JSON开头，而是从Ruby哈希开始：

require 'json'

foo = {
  "data" => {
    "Chris" => {
      "long" => 5, 
      "lat" => 7
    }, 
    "Scott" => {
      "long" => 9,
      "lat" => 18
    }
  }
}

添加到您想要的任何其他哈希元素：

bob_hash = {'Bob' => {'long' => 10, 'lat' => 20}}
foo['data'].merge!(bob_hash)

merge!将bob_hash添加到foo['data']。然后，告诉哈希使用to_json输出其JSON表示。使用熟悉的Ruby结构更容易，并且让Ruby完成转换为JSON的繁重工作，而不是试图对现有的JSON字符串进行字符串操作。如果你有JSON，那么解析它并转换/修改生成的Ruby对象，然后再次输出JSON。

puts foo.to_json
# >> {"data":{"Chris":{"long":5,"lat":7},"Scott":{"long":9,"lat":18},"Bob":{"long":10,"lat":20}}}

我建议也阅读“How to convert JSON to a hash, search for and change a value”，因为它是访问结果哈希值的有用替代方法。

Answer 2

username = 'Chris'
sections.each do |user_coords|
  user_coords.each do |user, coords|
    if user == username then
      coords.each do |lat_long|
        lat_long['lat']  = 123 # Your value here...
        lat_long['long'] = 456 # Your value here...
      end
    end
  end
end
sections.to_json # => '[{"Chris":[{"long":456,"lat":123}]}...]'

在Ruby中编辑JSON数组内容

2 个答案: