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@QUANON(QUANON)

[Ruby] HTTP の QUERY メソッドを Rack で実装する

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Last updated at Posted at 2026-06-26

はじめに

新しい HTTP メソッド QUERY が、RFC 10008 (Proposed Standard) として公開されました。

これを知るきっかけになったのが X の以下のポストです。

早速この QUERY メソッドを Python で実装した記事を見つけました。

この記事に感化され Ruby でも実装してみようと思います。

準備

必要な Gem のインストール

Puma と Rack をインストールします。

Gemfile
source 'https://rubygems.org'

# Active Support コア拡張のメソッドを利用したい。
gem 'activesupport', require: false

gem 'puma'
gem 'rack'

$ bundle install

Puma の設定

Puma 用の設定を記載した Ruby ファイル puma.rb を用意します。Puma は QUERY メソッドをサポートしていないため、supported_http_methods で許可する HTTP メソッドとして明示的に指定する必要があります。

puma.rb
port ENV.fetch('PORT', 9292)

# `QUERY` を追加する。
supported_http_methods %w(HEAD GET POST PUT DELETE OPTIONS TRACE PATCH QUERY)

Rack アプリケーションの用意

QUERY メソッド検証用の Rack アプリケーション QueryApp を用意します。

要件

  • [RFC 10008] QUERY はセーフ (読み取り専用) かつべき等。
  • [RFC 10008] クエリを URL ではなくリクエストボディに含める。
    • [RFC 10008] Content-Type が必須。
    • 欠落や構文エラーは 400 Bad Request。
    • [RFC 10008] 非対応メディアタイプは 415 Unsupported Media Type。
    • 構文は妥当だが処理不能 (クエリオブジェクトでない) 場合は 422 Unprocessable Entity。
  • [RFC 10008] 成功 (200) レスポンスの Content-Location に「同等の結果を GET で返すリソース」を含める。
  • [RFC 10008] レスポンスはキャッシュ可能。
    • [PFC 10008] キャッシュキーにリクエストボディを含める必要がある。
    • 正規化したクエリからバリデータ (ETag) を計算する。
  • レスポンスのメディアタイプを Accept で要求されたが非対応の場合は 406 Not Acceptable を返す。
  • If-None-Match による条件付きリクエストに対応し、一致時は 304 Not Modified を返す。
  • 非対応メソッドには Allow ヘッダ付きで 405 Method Not Allowed を返す。
  • [PFC 10008] Accept-Query で QUERY を受け付ける。そして受信可能な MIME メディアタイプを通知する。

コード

config.ru
require 'json'
require 'uri'
require 'digest'
require 'rack/utils'
require 'active_support/core_ext/object/blank'

DATASET = [
  { 'id' => 1, 'name' => '志那都',       'style' => '1A', 'price' => 8_500 },
  { 'id' => 2, 'name' => 'メルフォーレ', 'style' => '2A', 'price' => 2_490 },
  { 'id' => 3, 'name' => 'カルレダ',     'style' => '4A', 'price' => 18_900 },
  { 'id' => 4, 'name' => 'ホーネット',   'style' => '2A', 'price' => 2_490 },
  { 'id' => 5, 'name' => 'キョウト',     'style' => '1A', 'price' => 49_900 }
].freeze

class QueryApp
  RESOURCE_PATH = '/search'
  ALLOW_METHODS = 'GET, QUERY, OPTIONS'
  SUPPORTED_QUERY_TYPES = %w(application/json).freeze
  ACCEPT_QUERY = SUPPORTED_QUERY_TYPES.join(', ').freeze
  ACCEPTABLE_RESPONSE_TYPES = ['application/json', 'application/*', '*/*'].freeze

  Response = Data.define(:status, :headers, :body) do
    def to_a = [status, headers, body]
  end

  def call(env) = dispatch(env).to_a

  private

  def dispatch(env)
    return not_found unless env['PATH_INFO'] == RESOURCE_PATH

    case env['REQUEST_METHOD']
    when 'QUERY'
      handle_query(env)
    when 'GET'
      handle_get(env)
    when 'OPTIONS'
      handle_options
    else
      method_not_allowed
    end
  end

  def handle_query(env)
    content_type = env['CONTENT_TYPE'].to_s

    return bad_request('Content-Type is required') if content_type.blank?

    media_type = content_type.split(';').first.to_s.strip.downcase
    return unsupported_media_type unless SUPPORTED_QUERY_TYPES.include?(media_type)

    return not_acceptable unless acceptable?(env['HTTP_ACCEPT'].to_s)

    request_body = env['rack.input'].read.to_s
    conditions =
      begin
        parse_json_object(request_body)
      rescue JSON::ParserError
        return bad_request('Request body is not valid JSON')
      end

    return unprocessable_entity('Request content must be a JSON object') unless conditions

    effective_conditions = no_transform?(env) ? conditions : normalize(conditions)
    etag = weak_etag(effective_conditions)
    content_location = build_content_location(effective_conditions)

    cache_headers = {
      'content-location' => content_location,
      'cache-control' => 'max-age=60',
      'etag' => etag,
      'vary' => 'Accept',
      'accept-query' => ACCEPT_QUERY,
    }

    return Response.new(status: 304, headers: cache_headers, body: []) if env['HTTP_IF_NONE_MATCH'].to_s.strip == etag

    results = run_query(conditions)
    payload = JSON.generate('query' => conditions, 'count' => results.size, 'results' => results)

    headers = { 'content-type' => 'application/json' }.merge(cache_headers)
    Response.new(status: 200, headers: headers, body: [payload])
  end

  def handle_get(env)
    params = Rack::Utils.parse_nested_query(env['QUERY_STRING'])

    conditions = {}
    conditions['q'] = params['q'] unless params['q'].blank?
    conditions['style'] = params['style'] unless params['style'].blank?
    conditions['max_price'] = Integer(params['max_price']) unless params['max_price'].blank?

    results = run_query(conditions)

    Response.new(
      status: 200,
      headers: { 'content-type' => 'application/json' },
      body: [JSON.generate('query' => conditions, 'count' => results.size, 'results' => results)]
    )
  rescue ArgumentError
    bad_request('max_price must be an integer')
  end

  def handle_options
    headers = {
      'allow' => ALLOW_METHODS,
      'accept-query' => ACCEPT_QUERY
    }

    Response.new(status: 204, headers: headers, body: [])
  end

  def run_query(conditions)
    q = conditions['q']
    style = conditions['style']
    max_price = conditions['max_price']

    DATASET.select do |row|
      (q.blank? || row['name'].include?(q.to_s)) &&
      (style.blank? || row['style'] == style) &&
      (max_price.nil? || row['price'] <= max_price.to_i)
    end
  end

  def parse_json_object(body)
    return {} if body.empty?

    json = JSON.parse(body)
    return nil unless json.is_a?(Hash)

    json
  end

  def build_content_location(conditions)
    query_string = URI.encode_www_form(conditions)
    query_string.empty? ? RESOURCE_PATH : "#{RESOURCE_PATH}?#{query_string}"
  end

  def weak_etag(conditions) = %(W/"#{Digest::SHA256.hexdigest(JSON.generate(conditions))[0, 16]}")

  def no_transform?(env)
    env['HTTP_CACHE_CONTROL'].to_s.split(',').map(&:strip).include?('no-transform')
  end

  def normalize(conditions) = conditions.reject { |_k, v| v.blank? }.sort.to_h

  def not_found
    Response.new(
      status: 404,
      headers: { 'content-type' => 'application/json' },
      body: [JSON.generate('error' => 'Not Found')]
    )
  end

  def method_not_allowed
    Response.new(
      status: 405,
      headers: { 'content-type' => 'application/json', 'allow' => ALLOW_METHODS, 'accept-query' => ACCEPT_QUERY },
      body: [JSON.generate('error' => 'Method Not Allowed', 'allow' => %w[GET QUERY OPTIONS])]
    )
  end

  def unsupported_media_type
    Response.new(
      status: 415,
      headers: { 'content-type' => 'application/json', 'accept-query' => ACCEPT_QUERY },
      body: [JSON.generate('error' => 'Unsupported Media Type', 'supported' => SUPPORTED_QUERY_TYPES)]
    )
  end

  def acceptable?(accept)
    return true if accept.blank?

    accept.split(',').map { it.split(';').first.strip.downcase }.any? do |type|
      ACCEPTABLE_RESPONSE_TYPES.include?(type)
    end
  end

  def not_acceptable
    Response.new(
      status: 406,
      headers: { 'content-type' => 'application/json' },
      body: [JSON.generate('error' => 'Not Acceptable', 'supported' => SUPPORTED_QUERY_TYPES)]
    )
  end

  def unprocessable_entity(message)
    Response.new(
      status: 422,
      headers: { 'content-type' => 'application/json' },
      body: [JSON.generate('error' => message)]
    )
  end

  def bad_request(message)
    Response.new(
      status: 400,
      headers: { 'content-type' => 'application/json' },
      body: [JSON.generate('error' => message)]
    )
  end
end

run(QueryApp.new)

検証

Puma を使用して QueryApp を起動します。

$ bundle exec puma -C puma.rb config.ru

require 'net/http'
require 'uri'

def show(title, response)
  puts("=== #{title} ===")
  puts("status: #{response.code}")
  %w(content-location etag accept-query allow cache-control).each do |header|
    puts("#{header}: #{response[header]}") if response[header]
  end
  puts("body: #{response.body}")
  puts
end

http = Net::HTTP.new('localhost', 9292)

# 1. [RFC 10008] JSON ボディを含む正常な QUERY の場合は 200。
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search', { 'Content-Type' => 'application/json' })
req.body = '{"style":"2A","max_price":3000}'
show('1. QUERY (200 + Content-Location/ETag/Accept-Query)', http.request(req))

# 2. [RFC 10008] Content-Type が欠落している場合は 400。
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search')
req.body = '{}'
show('2. Missing Content-Type -> 400', http.request(req))

# 3. [RFC 10008] 非対応の MIME メディアタイプの場合は 415。
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search', { 'Content-Type' => 'text/plain' })
req.body = 'x'
show('3. Unsupported media type -> 415', http.request(req))

# 4. QueryApp は POST 非対応なので 405 (Allow ヘッダを含む)。
req = Net::HTTP::Post.new('/search', { 'Content-Type' => 'application/json' })
req.body = '{}'
show('4. POST -> 405 + Allow', http.request(req))

# 5. [RFC 10008] Content-Location への GET が同等の結果を返すこと。
show('5. GET equivalent (Content-Location)', http.get('/search?max_price=3000&style=2A'))

# 6. 非対応の MIME メディアタイプを Accept で指定する場合は 406。
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search', { 'Content-Type' => 'application/json', 'Accept' => 'text/html' })
req.body = '{}'
show('6. Accept text/html -> 406', http.request(req))

# 7. 不正な構文の JSON の場合は 400。
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search', { 'Content-Type' => 'application/json' })
req.body = 'not json'
show('7. Malformed JSON -> 400', http.request(req))

# 8. 構文は妥当だがオブジェクトでない JSON の場合は 422。
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search', { 'Content-Type' => 'application/json' })
req.body = '[1, 2, 3]'
show('8. Valid JSON but not an object -> 422', http.request(req))

# 9. If-None-Match を付けて再送する場合 304。
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search', { 'Content-Type' => 'application/json' })
req.body = '{"style":"2A","max_price":3000}'
first = http.request(req)
etag = first['etag']
req = Net::HTTPGenericRequest.new('QUERY', true, true, '/search', { 'Content-Type' => 'application/json', 'If-None-Match' => etag })
req.body = '{"style":"2A","max_price":3000}'
show("9. If-None-Match (#{etag}) -> 304", http.request(req))

=== 1. QUERY (200 + Content-Location/ETag/Accept-Query) ===
status: 200
content-location: /search?max_price=3000&style=2A
etag: W/"0f1f4e90e0d4f662"
accept-query: application/json
cache-control: max-age=60
body: {"query":{"style":"2A","max_price":3000},"count":2,"results":[{"id":2,"name":"メルフォーレ","style":"2A","price":2490},{"id":4,"name":"ホーネット","style":"2A","price":2490}]}

=== 2. Missing Content-Type -> 400 ===
status: 400
body: {"error":"Content-Type is required"}

=== 3. Unsupported media type -> 415 ===
status: 415
accept-query: application/json
body: {"error":"Unsupported Media Type","supported":["application/json"]}

=== 4. POST -> 405 + Allow ===
status: 405
accept-query: application/json
allow: GET, QUERY, OPTIONS
body: {"error":"Method Not Allowed","allow":["GET","QUERY","OPTIONS"]}

=== 5. GET equivalent (Content-Location) ===
status: 200
body: {"query":{"style":"2A","max_price":3000},"count":2,"results":[{"id":2,"name":"メルフォーレ","style":"2A","price":2490},{"id":4,"name":"ホーネット","style":"2A","price":2490}]}

=== 6. Accept text/html -> 406 ===
status: 406
body: {"error":"Not Acceptable","supported":["application/json"]}

=== 7. Malformed JSON -> 400 ===
status: 400
body: {"error":"Request body is not valid JSON"}

=== 8. Valid JSON but not an object -> 422 ===
status: 422
body: {"error":"Request content must be a JSON object"}

=== 9. If-None-Match (W/"0f1f4e90e0d4f662") -> 304 ===
status: 304
content-location: /search?max_price=3000&style=2A
etag: W/"0f1f4e90e0d4f662"
accept-query: application/json
cache-control: max-age=60
body:

バージョン情報

言語・Gem バージョン
Ruby 4.0.5
Puma 8.0.2
Rack 3.2.6

参考

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