{"id":3112,"date":"2013-08-30T15:07:20","date_gmt":"2013-08-30T06:07:20","guid":{"rendered":"http:\/\/www.techscore.com\/blog\/?p=3112"},"modified":"2018-11-14T16:33:54","modified_gmt":"2018-11-14T07:33:54","slug":"rails-select%e3%81%99%e3%82%8b%e3%82%ab%e3%83%a9%e3%83%a0%e3%82%92%e8%bf%bd%e5%8a%a0%e3%81%99%e3%82%8bscope%e3%82%92%e5%ae%9a%e7%be%a9%e3%81%99%e3%82%8b","status":"publish","type":"post","link":"https:\/\/www.techscore.com\/blog\/2013\/08\/30\/rails-select%e3%81%99%e3%82%8b%e3%82%ab%e3%83%a9%e3%83%a0%e3%82%92%e8%bf%bd%e5%8a%a0%e3%81%99%e3%82%8bscope%e3%82%92%e5%ae%9a%e7%be%a9%e3%81%99%e3%82%8b\/","title":{"rendered":"Rails: SELECT\u3059\u308b\u30ab\u30e9\u30e0\u3092\u8ffd\u52a0\u3059\u308bscope\u3092\u5b9a\u7fa9\u3059\u308b"},"content":{"rendered":"

\u3053\u3093\u306b\u3061\u306f\u3001\u9234\u6728\u3067\u3059\u3002<\/p>\n

 <\/p>\n

Rails \u3067 SELECT \u3059\u308b\u30ab\u30e9\u30e0\u3092\u8ffd\u52a0\u3059\u308b scope \u3092\u5b9a\u7fa9\u3059\u308b\u65b9\u6cd5\u3092\u3054\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n

 <\/p>\n

\u3084\u308a\u305f\u3044\u3053\u3068<\/h2>\n

SELECT \u3059\u308b\u30ab\u30e9\u30e0\u3092\u6307\u5b9a\u3059\u308b\u306b\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b select \u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u307e\u3059\u3002<\/p>\n

User.select('email')<\/pre>\n
\u4ed6\u306e\u30ab\u30e9\u30e0\u304b\u3089\u8a08\u7b97\u3057\u305f\u5024\u304c\u5fc5\u8981\u306a\u5834\u5408\u3001\u4f8b\u3048\u3070\u59d3\uff08family_name\uff09\u3068\u540d\uff08given_name\uff09\u3092\u7d50\u5408\u3057\u305f\u5024\u3092 full_name \u3068\u3044\u3046\u540d\u524d\u3067\u6b32\u3057\u3044\u3068\u3044\u3046\u5834\u5408\u306f\u6b21\u306e\u3088\u3046\u306b\u306a\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n
User.select('family_name || given_name AS full_name')<\/pre>\n
\u8907\u6570\u500b\u6240\u3067\u4f7f\u3046\u5834\u5408\u306f scope \u3068\u3057\u3066\u5b9a\u7fa9\u3057\u3066\u304a\u304f\u3068\u4fbf\u5229\u3067\u3059\u3002<\/p>\n
class User < ActiveRecord::Base\r\n\r\n  scope :select_full_name, lambda {\r\n    select('family_name || given_name AS full_name')\r\n  }\r\n\r\nend<\/pre>\n
scope \u3092\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u30b3\u30fc\u30c9\u304c\u3059\u3063\u304d\u308a\u3057\u3001\u307f\u3093\u306a\u30cf\u30c3\u30d4\u30fc\uff01\u3068\u601d\u3044\u304d\u3084\u3002<\/p>\n
\u6b21\u306e\u30b3\u30fc\u30c9\u3092\u898b\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n
User.select_full_name.each do |user|\r\n  puts \"#{user.full_name} \u3055\u3093\u306e\u8a95\u751f\u65e5\u306f #{user.birthday} \u3067\u3059\"\r\nend<\/pre>\n
\u5b9f\u884c\u3059\u308b\u3068\u300cActiveModel::MissingAttributeError: missing attribute: birthday\u300d\u3068\u3044\u3046\u4f8b\u5916\u304c\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n
\u5f53\u305f\u308a\u524d\u3067\u306f\u3042\u308b\u306e\u3067\u3059\u304c\u3001select \u3067 full_name \u3057\u304b\u6307\u5b9a\u3057\u3066\u3044\u306a\u3044\u306e\u3067\u3001birthday \u306b\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3059\u308b\u3068\u4f8b\u5916\u304c\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n
 <\/p>\n
\u3057\u304b\u3057\u3001\u305d\u3046\u3067\u306f\u306a\u304f\u3066\u3001full_name \u300c\u3082\u300dSELECT \u3057\u3066\u304d\u3066\u307b\u3057\u3044\u3093\u3067\u3059\u3002<\/p>\n
full_name \u300c\u3060\u3051\u300dSELECT \u3059\u308b\u306e\u3067\u306f\u306a\u304f\u3001full_name\u300c\u3082\u300dSELECT \u3057\u3066\u307b\u3057\u3044\u3093\u3067\u3059\u3002<\/p>\n
 <\/p>\n
\u3053\u306e\u3088\u3046\u306b\u5168\u3066\u306e\u30ab\u30e9\u30e0\u3068\u8a08\u7b97\u3057\u305f\u5024\uff08full_name\uff09\u3092 SELECT \u3057\u305f\u3044\u3001\u3068\u3044\u3046\u30b1\u30fc\u30b9\u306f\u6642\u3005\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n
\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u5bfe\u5fdc\u3059\u308b\u3053\u3068\u3082\u3067\u304d\u307e\u3059\u304c\u3001\u3042\u307e\u308a\u7dba\u9e97\u306a\u89e3\u6c7a\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n
# \u3053\u308c\u3060\u3068 scope \u3067\u306f\u306a\u3044\u306e\u3067\u3001\u8907\u6570\u306e\u5834\u6240\u306b\u540c\u3058\u30b3\u30fc\u30c9\u304c\u6563\u3089\u3070\u308b\u3053\u3068\u306b\u306a\u308b.\r\nUser.select('*, family_name || given_name AS full_name')\r\n\r\n# \u3053\u308c\u3060\u3068 select('*') \u306e\u6307\u5b9a\u304c\u975e\u5e38\u306b\u9762\u5012\u3067\u5fd8\u308c\u3084\u3059\u3044.\r\nUser.select('*').select_full_name<\/pre>\n
\u3053\u308c\u306a\u3089\u3069\u3046\u3067\u3057\u3087\u3046\u304b\uff1f<\/p>\n
class User < ActiveRecord::Base\r\n\r\n  scope :select_full_name, lambda {\r\n    select('*, family_name || given_name AS full_name')\r\n  }\r\n\r\nend<\/pre>\n
\u3053\u308c\u3060\u3068\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u3001\u672c\u5f53\u306b\u6307\u5b9a\u3057\u305f\u30ab\u30e9\u30e0\u3060\u3051\u5fc5\u8981\u306a\u5834\u5408\u306b\u5bfe\u5fdc\u3067\u304d\u307e\u305b\u3093\uff08select_full_name \u306e\u4e2d\u3067 select('*, ...') \u3068\u3057\u3066\u3044\u308b\u305f\u3081\uff09\u3002<\/p>\n
User.select(:email).select_full_name<\/pre>\n
\u4ee5\u4e0a\u306e\u8ab2\u984c\u3092\u89e3\u6c7a\u3059\u308b\u65b9\u6cd5\u306f\u3042\u308b\u306e\u3067\u3057\u3087\u3046\u304b\u3002<\/p>\n
 <\/p>\n
SELECT\u3059\u308b\u30ab\u30e9\u30e0\u3092\u8ffd\u52a0\u3059\u308bscope\u3092\u5b9a\u7fa9\u3059\u308b<\/h2>\n
\u3044\u304d\u306a\u308a\u7b54\u3048\u3067\u3059\u304c\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u5b9f\u88c5\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
class User < ActiveRecord::Base\r\n\r\n  scope :select_full_name, lambda {\r\n    # (1) \u4eca\u306e scope \u3092\u53d6\u308b (\u7121\u3051\u308c\u3070 relation)\r\n    scope = current_scope || relation\r\n\r\n    # (2) select \u304c\u6307\u5b9a\u3055\u308c\u3066\u3044\u306a\u304b\u3063\u305f\u3089 select('*') \u3059\u308b.\r\n    scope = scope.select('*') if scope.select_values.blank?\r\n\r\n    # \u305d\u308c\u306b\u5bfe\u3057\u3066\u672c\u6765\u3084\u308a\u305f\u304b\u3063\u305f select \u3092\u884c\u3046.\r\n    scope.select('family_name || given_name AS full_name')\r\n  }\r\n\r\nend<\/pre>\n
(1) \u3067\u306f\u73fe\u5728\u306e scope \u3092\u53d6\u5f97\u3057\u3066\u3044\u307e\u3059\u3002\u4f55\u3082 scope \u304c\u6307\u5b9a\u3055\u308c\u3066\u3044\u306a\u3044\u5834\u5408\u306f nil \u304c\u8fd4\u3055\u308c\u308b\u306e\u3067\u4ee3\u308f\u308a\u306b relation \u3092\u53d6\u5f97\u3057\u307e\u3059\u3002<\/p>\n
(2) \u3067\u306f\u3001if scope.select_values.blank? \u306b\u3088\u3063\u3066\u65e2\u306b select \u304c\u884c\u308f\u308c\u3066\u3044\u308b\u304b\u5224\u65ad\u3057\u3066\u3044\u307e\u3059\u3002select_values \u306f select \u3067\u6307\u5b9a\u3055\u308c\u305f\u30ab\u30e9\u30e0\u306e\u4e00\u89a7\u3092\u8fd4\u3059\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n
(3) \u3067\u3088\u3046\u3084\u304f\u672c\u6765\u3084\u308a\u305f\u304b\u3063\u305f select('family_name || given_name AS full_name') \u3092\u6307\u5b9a\u3057\u307e\u3059\u3002<\/p>\n
\u3053\u3046\u3059\u308b\u3053\u3068\u3067\u3001\u65e2\u306b select \u304c\u6307\u5b9a\u3055\u308c\u3066\u3044\u308b\u5834\u5408\u306f\u305d\u308c\u306b\u8ffd\u52a0\u3001\u305d\u3046\u3067\u306a\u3051\u308c\u3070 select('*') \u3057\u305f\u4e0a\u3067\u8ffd\u52a0\u3059\u308b\u3001\u3068\u3044\u3046\u3053\u3068\u304c\u5b9f\u73fe\u3067\u304d\u307e\u3059\u3002<\/p>\n
\u4ee5\u4e0b\u306e\u3088\u3046\u306b add_select_field \u3068\u3044\u3046\u30e1\u30bd\u30c3\u30c9\u306b\u5206\u5272\u3057\u3066\u304a\u3051\u3070\u3001\u540c\u69d8\u306e\u51e6\u7406\u3092\u884c\u3046\u5834\u5408\u306b\u4fbf\u5229\u3067\u3057\u3087\u3046\u3002<\/p>\n
class User < ActiveRecord::Base\r\n\r\n  scope :add_select_field, lambda {|*fields|\r\n    scope = current_scope || relation\r\n    scope = scope.select(Arel.star) if scope.select_values.blank?\r\n    scope.select(*fields)\r\n  }\r\n\r\n  scope :select_age, lambda {\r\n    add_select_field('EXTRACT(year from AGE(birthday)) AS age')\r\n  }\r\n\r\nend<\/pre>\n
Enjoy Rails!!<\/p>\n
 <\/p>\n","protected":false},"excerpt":{"rendered":"
\u3053\u3093\u306b\u3061\u306f\u3001\u9234\u6728\u3067\u3059\u3002<\/p>\n
 <\/p>\n
Rails \u3067 SELECT \u3059\u308b\u30ab\u30e9\u30e0\u3092\u8ffd\u52a0\u3059\u308b scope \u3092\u5b9a\u7fa9\u3059\u308b\u65b9\u6cd5\u3092\u3054\u7d39\u4ecb\u3057\u307e\u3059\u3002
\u7d9a\u304d\u3092\u8aad\u3080...<\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[18],"tags":[22],"_links":{"self":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/3112"}],"collection":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/comments?post=3112"}],"version-history":[{"count":1,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/3112\/revisions"}],"predecessor-version":[{"id":17915,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/posts\/3112\/revisions\/17915"}],"wp:attachment":[{"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/media?parent=3112"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/categories?post=3112"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.techscore.com\/blog\/wp-json\/wp\/v2\/tags?post=3112"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}