在Ruby中编辑JSON数组内容
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
如何才能做到这一点?
这是如何访问JSON中的各个元素:
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
。
如果哈希是正常定义的,那么它会更干净/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,使用您的散列看起来像这样:
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first
使用(或[0]
)来获取哈希元素才能闻到它的味道。
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的人,其中long = 10且lat = 20
听起来你没有很好地掌握操作/访问哈希,或者如何转换为/从JSON转换。 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}}}
我建议阅读“ 如何将JSON转换为哈希,搜索和更改值 ”,因为它是访问结果哈希值的有用替代方法。
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}]}...]'