Ruby How to turn a hash into HTTP parameters

Question

That is pretty easy with a plain hash like     a   gt   a    b   gt   b      which would translate into    a a amp b b    But what do you do with something more complex like     a   gt   a    b   gt    c    d    e       which should translate into    a a amp b 0  c amp b 1  d amp b 2  e     Or even worse   what to do  with something like      a   gt   a    b   gt     c   gt   c    d   gt   d      e   gt   e    f   gt   f      Thanks for the much appreciated help with that

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Here s a short and sweet one liner if you only need to support simple ASCII key value query strings   hash     foo    gt   bar    fooz    gt  123      gt    foo   gt  bar    fooz   gt 123  query string   hash to a map    x     x 0     x 1      join   amp        gt   foo bar amp fooz 123

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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  amp  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  gt    a   gt   a    b   gt   b   to query hash nil     gt    a  gt  a    b  gt  b    2 4 2  020  gt    a   gt   a    b   gt   b   to query    gt   a a amp b b   2 4 2  021  gt    a   gt   a    b   gt    c    d    e    to query hash nil     gt    a  gt  a    b 0    gt  c    b 1    gt  d    b 2    gt  e    2 4 2  022  gt    a   gt   a    b   gt    c    d    e    to query    gt   a a amp b 5B0 5D c amp b 5B1 5D d amp b 5B2 5D e

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If you are in the context of a Faraday request  you can also just pass the params hash as the second argument and faraday takes care of making proper param URL part out of it   faraday instance get url  params hsh

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class Hash   def to params     params          stack           each do  k  v        if v is a  Hash          stack  lt  lt   k v        elsif v is a  Array          stack  lt  lt   k Hash from array v         else         params  lt  lt     k    v  amp         end     end      stack each do  parent  hash        hash each do  k  v          if v is a  Hash            stack  lt  lt      parent    k     v          else           params  lt  lt     parent    k     v  amp           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

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Update  This functionality was removed from the gem   Julien  your self-answer is a good one  and I ve shameless borrowed from it  but it doesn t properly escape reserved characters  and there are a few other edge cases where it breaks down   require  addressable uri  uri   Addressable  URI new uri query values     a   gt   a    b   gt    c    d    e    uri query     gt   a a amp b 0  c amp b 1  d amp b 2  e  uri query values     a   gt   a    b   gt     c   gt   c    d   gt   d      e   gt   e    f   gt   f     uri query     gt   a a amp b 0  c  c amp b 0  d  d amp b 1  e  e amp b 1  f  f  uri query values     a   gt   a    b   gt    c   gt   c    d   gt   d    uri query     gt   a a amp b c  c amp b d  d  uri query values     a   gt   a    b   gt    c   gt   c    d   gt  true   uri query     gt   a a amp b c  c amp b d   uri query values     a   gt   a    b   gt    c   gt   c    d   gt  true    e   gt      uri query     gt   a a amp b c  c amp b d     The gem is  addressable   gem install addressable

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Steal from Merb     File merb core ext hash rb  line 87 def to params   params        stack         each do  k  v      if v is a  Hash        stack  lt  lt   k v      else       params  lt  lt     k    v  amp       end   end    stack each do  parent  hash      hash each do  k  v        if v is a  Hash          stack  lt  lt      parent    k     v        else         params  lt  lt     parent    k     v  amp         end     end   end    params chop    trailing  amp    params end   See http   noobkit com show ruby gems development merb hash to params html

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a  gt  a    b  gt  b    c  gt  c   map   x v     x    v     reduce  x v     x  amp   v       a a amp b b amp c c    Here s another way  For simple queries

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The best approach it is to use Hash to params which is the one working fine with arrays    a  1  b   1 2 3   to param  a 1 amp b   1 amp b   2 amp b   3

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I know this is an old question  but I just wanted to post this bit of code as I could not find a simple gem to do just this task for me   module QueryParams    def self encode value  key   nil      case value     when Hash  then value map    k v  encode v  append key key k     join   amp        when Array then value map    v  encode v     key        join   amp        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   Rolled up as gem here  https   github com simen queryparams

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I like using this gem   https   rubygems org gems php http build query  Sample usage   puts PHP http build query   a   gt  b   c   gt  d   e   gt    hello   gt  world   bah   gt  black     hello   gt  world   bah   gt  black         a b amp c d amp e 5B0 5D 5Bbah 5D black amp e 5B0 5D 5Bhello 5D world amp e 5B1 5D 5Bbah 5D black amp e 5B1 5D 5Bhello 5D world

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For basic  non-nested hashes  Rails ActiveSupport has Object to query    gt  gt    a   gt   a    b   gt    c    d    e    to query   gt   a a amp b 5B 5D c amp b 5B 5D d amp b 5B 5D e   gt  gt  CGI unescape   a   gt   a    b   gt    c    d    e    to query    gt   a a amp b   c amp b   d amp b   e    http   api rubyonrails org classes Object html method-i-to query

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2 6 3  001  gt  hash     a   gt   quot a quot    b   gt    quot c quot    quot d quot    quot e quot      gt    a  gt  quot a quot    b  gt   quot c quot    quot d quot    quot e quot    2 6 3  002  gt  hash to a map    x   quot   x 0     x 1  class    Array   x 1  join  quot   quot     x 1   quot     join  quot  amp  quot     gt   quot a a amp b c d e quot

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No need to load up the bloated ActiveSupport or roll your own  you can use Rack  Utils build query and Rack  Utils build nested query  Here s a blog post that gives a good example   require  rack   Rack  Utils build query    authorization token   foo     access level   moderator     previous   index         gt   authorization token foo amp access level moderator amp previous index    It even handles arrays   Rack  Utils build query    a   gt   a    b   gt    c    d    e          gt   a a amp b c amp b d amp b e  Rack  Utils parse query       gt    a   gt  a    b   gt   c    d    e      Or the more difficult nested stuff   Rack  Utils build nested query    a   gt   a    b   gt     c   gt   c    d   gt   d      e   gt   e    f   gt   f            gt   a a amp b   c  c amp b   d  d amp b   e  e amp b   f  f  Rack  Utils parse nested query       gt    a   gt  a    b   gt    c   gt  c    d   gt  d    e   gt  e    f   gt  f

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If you are using Ruby 1 9 2 or later  you can use URI encode www form if you don t need arrays   E g   from the Ruby docs in 1 9 3    URI encode www form    q    ruby      lang    en        gt   q ruby amp lang en  URI encode www form  q    gt   ruby    lang    gt   en      gt   q ruby amp lang en  URI encode www form  q    gt    ruby    perl     lang    gt   en      gt   q ruby amp q perl amp lang en  URI encode www form    q    ruby      q    perl      lang    en        gt   q ruby amp q perl amp lang en    You ll notice that array values are not set with key names containing    like we ve all become used to in query strings  The spec that encode www form uses is in accordance with the HTML5 definition of application x-www-form-urlencoded data

[ruby] Ruby: How to turn a hash into HTTP parameters?

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