使用普通哈希算法很容易实现，比如
{:a => "a", :b => "b"}
这将转换为
"a=a&b=b"
但是如果你遇到更加复杂的东西该怎么办呢？比如说：
{:a => "a", :b => ["c", "d", "e"]}
这应该被翻译成
"a=a&b[0]=c&b[1]=d&b[2]=e"
或者更糟的是，如何处理这样的内容：
{:a => "a", :b => [{:c => "c", :d => "d"}, {:e => "e", :f => "f"}]
感谢您对此的大力帮助！
对于基本的非嵌套哈希，Rails/ActiveSupport提供了Object#to_query方法。
>> {:a => "a", :b => ["c", "d", "e"]}.to_query
=> "a=a&b%5B%5D=c&b%5B%5D=d&b%5B%5D=e"
>> CGI.unescape({:a => "a", :b => ["c", "d", "e"]}.to_query)
=> "a=a&b[]=c&b[]=d&b[]=e"
http://api.rubyonrails.org/classes/Object.html#method-i-to_query
require 'active_support/all' - Dorian{ a: nil, b: '1'}.to_query == "a=&b=1"，但是Rack和CGI都将a=解析为空字符串，而不是nil。我不确定其他服务器的支持情况，但是对于Rails来说，正确的查询字符串应该是a&b=1。我认为Rails无法生成自己可以正确解析的查询字符串是错误的... - jsmartt如果您使用的是Ruby 1.9.2或更高版本，且不需要使用数组，您可以使用URI.encode_www_form。
例如（来自1.9.3版本的Ruby文档）：
URI.encode_www_form([["q", "ruby"], ["lang", "en"]])
#=> "q=ruby&lang=en"
URI.encode_www_form("q" => "ruby", "lang" => "en")
#=> "q=ruby&lang=en"
URI.encode_www_form("q" => ["ruby", "perl"], "lang" => "en")
#=> "q=ruby&q=perl&lang=en"
URI.encode_www_form([["q", "ruby"], ["q", "perl"], ["lang", "en"]])
#=> "q=ruby&q=perl&lang=en"
你会注意到，数组值不像我们在查询字符串中习惯的那样使用包含[]的键名进行设置。 encode_www_form使用的规范符合HTML5对application/x-www-form-urlencoded数据的定义。
{：c =>“c”，：d => true}似乎已被检查，因此作为字符串发送。 - user208769ruby -ruri -e 'puts RUBY_VERSION; puts URI.encode_www_form({:a => "a", :b => {:c => "c", :d => true}, :e => []})' # 输出2.0.0 a=a&b=%7B%3Ac%3D%3E%22c%22%2C+%3Ad%3D%3Etrue%7D& - user208769Addressable::URI 和 ActiveSupport 的 Object#to_query 有不同的结果。 - Matt Huggins更新：这个功能已经从宝石中删除。
Julien，你的自我回答很好，我也不要脸地借鉴了它，但它没有正确转义保留字符，并且在一些其他边缘情况下会出现问题。
require "addressable/uri"
uri = Addressable::URI.new
uri.query_values = {:a => "a", :b => ["c", "d", "e"]}
uri.query
# => "a=a&b[0]=c&b[1]=d&b[2]=e"
uri.query_values = {:a => "a", :b => [{:c => "c", :d => "d"}, {:e => "e", :f => "f"}]}
uri.query
# => "a=a&b[0][c]=c&b[0][d]=d&b[1][e]=e&b[1][f]=f"
uri.query_values = {:a => "a", :b => {:c => "c", :d => "d"}}
uri.query
# => "a=a&b[c]=c&b[d]=d"
uri.query_values = {:a => "a", :b => {:c => "c", :d => true}}
uri.query
# => "a=a&b[c]=c&b[d]"
uri.query_values = {:a => "a", :b => {:c => "c", :d => true}, :e => []}
uri.query
# => "a=a&b[c]=c&b[d]"
这个宝石是 'addressable'
gem install addressable
require 'rack'
Rack::Utils.build_query(
authorization_token: "foo",
access_level: "moderator",
previous: "index"
)
# => "authorization_token=foo&access_level=moderator&previous=index"
它甚至处理数组：
Rack::Utils.build_query( {:a => "a", :b => ["c", "d", "e"]} )
# => "a=a&b=c&b=d&b=e"
Rack::Utils.parse_query _
# => {"a"=>"a", "b"=>["c", "d", "e"]}
或者更复杂的嵌套结构:
Rack::Utils.build_nested_query( {:a => "a", :b => [{:c => "c", :d => "d"}, {:e => "e", :f => "f"}] } )
# => "a=a&b[][c]=c&b[][d]=d&b[][e]=e&b[][f]=f"
Rack::Utils.parse_nested_query _
# => {"a"=>"a", "b"=>[{"c"=>"c", "d"=>"d", "e"=>"e", "f"=>"f"}]}
:b 是一个包含两个哈希的数组。最终，:b 变成了一个包含一个更大的哈希的数组。 - Ed Ruderto_query方法也会合并这两个数组（v4.2）。 - Kelvin如果你只需要支持简单的 ASCII 键/值查询字符串，这里有一个简短而甜美的一行代码：
hash = {"foo" => "bar", "fooz" => 123}
# => {"foo"=>"bar", "fooz"=>123}
query_string = hash.to_a.map { |x| "#{x[0]}=#{x[1]}" }.join("&")
# => "foo=bar&fooz=123"
从Merb中借鉴：
# File merb/core_ext/hash.rb, line 87
def to_params
params = ''
stack = []
each do |k, v|
if v.is_a?(Hash)
stack << [k,v]
else
params << "#{k}=#{v}&"
end
end
stack.each do |parent, hash|
hash.each do |k, v|
if v.is_a?(Hash)
stack << ["#{parent}[#{k}]", v]
else
params << "#{parent}[#{k}]=#{v}&"
end
end
end
params.chop! # trailing &
params
end
请查看http://noobkit.com/show/ruby/gems/development/merb/hash/to_params.html
class Hash
def to_params
params = ''
stack = []
each do |k, v|
if v.is_a?(Hash)
stack << [k,v]
elsif v.is_a?(Array)
stack << [k,Hash.from_array(v)]
else
params << "#{k}=#{v}&"
end
end
stack.each do |parent, hash|
hash.each do |k, v|
if v.is_a?(Hash)
stack << ["#{parent}[#{k}]", v]
else
params << "#{parent}[#{k}]=#{v}&"
end
end
end
params.chop!
params
end
def self.from_array(array = [])
h = Hash.new
array.size.times do |t|
h[t] = array[t]
end
h
end
end
我知道这是一个老问题，但我想发表这段代码，因为我找不到一个简单的gem来完成这个任务。
module QueryParams
def self.encode(value, key = nil)
case value
when Hash then value.map { |k,v| encode(v, append_key(key,k)) }.join('&')
when Array then value.map { |v| encode(v, "#{key}[]") }.join('&')
when nil then ''
else
"#{key}=#{CGI.escape(value.to_s)}"
end
end
private
def self.append_key(root_key, key)
root_key.nil? ? key : "#{root_key}[#{key.to_s}]"
end
end
打包成gem文件发布在这里：https://github.com/simen/queryparams
URI.escape != CGI.escape 而对于 URL，你需要使用第一个。 - Ernest`CGI.escape("http://localhost/search?q=banana&limit=7")`
`=> "http%3A%2F%2Flocalhost%2Fsearch%3Fq%3Dbanana%26limit%3D7"`
`URI.escape("http://localhost/search?q=banana&limit=7")`
`=> "http://localhost/search?q=banana&limit=7"` - svale{:a=>"a", :b=>"b", :c=>"c"}.map{ |x,v| "#{x}=#{v}" }.reduce{|x,v| "#{x}&#{v}" }
"a=a&b=b&c=c"
require 'uri'
class Hash
def to_query_hash(key)
reduce({}) do |h, (k, v)|
new_key = key.nil? ? k : "#{key}[#{k}]"
v = Hash[v.each_with_index.to_a.map(&:reverse)] if v.is_a?(Array)
if v.is_a?(Hash)
h.merge!(v.to_query_hash(new_key))
else
h[new_key] = v
end
h
end
end
def to_query(key = nil)
URI.encode_www_form(to_query_hash(key))
end
end
2.4.2 :019 > {:a => "a", :b => "b"}.to_query_hash(nil)
=> {:a=>"a", :b=>"b"}
2.4.2 :020 > {:a => "a", :b => "b"}.to_query
=> "a=a&b=b"
2.4.2 :021 > {:a => "a", :b => ["c", "d", "e"]}.to_query_hash(nil)
=> {:a=>"a", "b[0]"=>"c", "b[1]"=>"d", "b[2]"=>"e"}
2.4.2 :022 > {:a => "a", :b => ["c", "d", "e"]}.to_query
=> "a=a&b%5B0%5D=c&b%5B1%5D=d&b%5B2%5D=e"