:call-seq:
  encode_query_string(object) -> string

Serialize a ruby object into HTTP query string parameters.

There is no standard for doing this, so we choose our own slightly
idiosyncratic format. The output closely matches the format understood by
Rails, Rack, and PHP.

If you don't want handling of complex objects and only want to handle
simple flat hashes, you may want to use `URI.encode_www_form` instead,
which implements HTML5-compliant URL encoded form data.

[Examples:]

Simple hashes

  >> encode_query_string({foo: 123, bar: 456})
  => 'foo=123&bar=456'

Simple arrays

  >> encode_query_string({foo: [1,2,3]})
  => 'foo[]=1&foo[]=2&foo[]=3'

Nested hashes

  >> encode_query_string({outer: {foo: 123, bar: 456}})
  => 'outer[foo]=123&outer[bar]=456'

Deeply nesting

  >> encode_query_string({coords: [{x: 1, y: 0}, {x: 2}, {x: 3}]})
  => 'coords[][x]=1&coords[][y]=0&coords[][x]=2&coords[][x]=3'

Null and empty values

  >> encode_query_string({string: '', empty: nil, list: [], hash: {}})
  => 'string=&empty&list&hash'

Nested nulls

  >> encode_query_string({foo: {string: '', empty: nil}})
  => 'foo[string]=&foo[empty]'

Multiple fields with the same name using ParamsArray

  >> encode_query_string(RestMan::ParamsArray.new([[:foo, 1], [:foo, 2], [:foo, 3]]))
  => 'foo=1&foo=2&foo=3'

Nested ParamsArray

  >> encode_query_string({foo: RestMan::ParamsArray.new([[:a, 1], [:a, 2]])})
  => 'foo[a]=1&foo[a]=2'

  >> encode_query_string(RestMan::ParamsArray.new([[:foo, {a: 1}], [:foo, {a: 2}]]))
  => 'foo[a]=1&foo[a]=2'



[Parameters:]

  - object (Hash,ParamsArray) -- The object to serialize

[Returns:]

  - (String) -- A string appropriate for use as an HTTP query string

[See Also:]

  - flatten_params
  - URI.encode_www_form
  - Object#to_query in ActiveSupport
  - http://php.net/manual/en/function.http-build-query.php
    http_build_query in PHP
  - Rack::Utils.build_nested_query in Rack

Notable differences from the ActiveSupport implementation:

- Empty hash and empty array are treated the same as nil instead of being
  omitted entirely from the output. Rather than disappearing, they will
  appear to be nil instead.

It's most common to pass a Hash as the object to serialize, but you can
also use a ParamsArray if you want to be able to pass the same key with
multiple values and not use the rack/rails array convention.

[since:]

  - 2.0.0