Ruby ã§ DB ãæ±ãã¡ãã£ã¨ããã¹ã¯ãªãããæ¸ãã¨ããActiveRecord ã§çSQLã使ãã¨è²ã æããã¨ãå¤ãã ãã®ããã®ã¡ã½ãããã¾ã¨ãã¦ã¿ãã äºåæºåï¼ establish_connection ä½æã»æ´æ°ç³»ï¼ execute æ¤ç´¢ç³»ï¼ select_all, select_one, select_rows, select_values, select_value ãã¬ã¼ã¹ãã«ãï¼ sanitize_sql_array äºåæºå establish_connection DBã¨ã®ã³ãã¯ã·ã§ã³ã確ç«ããã'mysql2', 'postgresql', 'redshift' ãªã©æ§ã ãªã¢ããã¿ã使ããã 以ä¸ã¯æ¥ç¶è¨å®ã®ä¸ä¾ã [MySQL] (è¦ mysql2 gem) require 'active_record' config = { adapter: 'mysql2
éè¨ã®ä»æ¹ããããActiveRecordã使ã£ãéè¨æ¹æ³ã«ã¤ãã¦ãããã調ã¹ãã®ã§ã¾ã¨ãã éè¨ç¨ã®ã¡ã½ãããcountãsumãminimumãmaximumãaverage
ActiveRecord ã§ãhas_many ã§å®ç¾©ããé¢é£ãããã¨ãããã®é¢é£ã®ä»¶æ°ãåå¾ããã®ã«ã¯ãcount, size, length ã®ï¼ã¤ã®ã¡ã½ãããããã¾ããããã«ã0ä»¶ãã©ããã調ã¹ãããã«ã¯ãempty? ã exists? ã¨ãã£ãåãåããã¡ã½ãããããã¾ãã ãããã®ä½¿ãåãã«ã¤ãã¦ããªãã¹ãåããããããªãããã«è§£èª¬ãã¦ã¿ããã¨æãã¾ãã ã¯ããã«ãhas_manyé¢é£ã¨ã¯ã次ã®ãããªã³ã¼ãä¾ã«ããããcompany.users ã®ãã¨ãæãã¾ãã class Company < ActiveRecord::Base has_many :users end class CompanyUsersController < ApplictaionController def index company = Company.find(params[:company_id
ã¨ããããã¸ã§ã¯ãã§ãã¼ã¿ãã¼ã¹ã®ãã¼ãã«å®ç¾©æ¸ã使ããå¿ è¦ããã£ãã®ã§ããã夿´ãããåº¦ã«æåã§ããã¥ã¡ã³ããä¿®æ£ããã®ã¯å¤§å¤é¢åãªãããèªåçæãããã¨ã«ãã¾ããã Rails ã® migration ã使ã£ã¦ç®¡çãã¦ãããã¼ãã«ç¾¤(MySQL)ã®å®ç¾©æ¸ã PDF ã§åºåããã¾ã§ã®ããã¼ãç´¹ä»ãã¾ãã ãã®è¨äºã®éãã«ä½æããã¨ä»¥ä¸ã®æ§å¼ã®å®ç¾©æ¸ã«ãªãã¾ãããã好ããªããã«ãã¶ã¤ã³ã夿´ãããã¨ãã§ãã¾ãã詳細ã¯å¾è¿°ã å ¨ä½ã®æµã rake db:migrate ã§ãã¼ãã«ã使/夿´ãã DBã®ã¹ãã¼ãæ§é ã XML å½¢å¼ã§åºåãã XML ã HTML ã«å¤æãã HTML ã PDF ã«å¤æãã ã®å¤§ãã4ã¤ã®æé ã§å®ç¾©æ¸ãåºåãã¾ãã 1. rake db:migrate ã§ãã¼ãã«ã使/夿´ãã ãã®é¨åã¯æ®æ®µã®éãã« migration ãã¡ã¤ã«ãè¨è¿°ããã ããªã®ã§ãã
ActiveRecord4ã§ãããªSQLã¯ã¨ãªã©ãæ¸ãã®ï¼ Mergeç·¨ ã§ã¯ãé¢é£å ã®scopeã使ããã¨ãã§ããmergeãç´¹ä»ãã¾ãããmergeã使ãäºã§ã夿´ã«å¼·ãã¯ã¨ãªãç¾ããçµã¿ç«ã¦ããã¨ãã§ãã¾ããã ä»åã¯ãActiveRecord4ã§æ¸ãã«ããSQLã¯ã¨ãªãã¡ãç´¹ä»ãã¾ãã æ¸ãã«ããã¯ã¨ãªã¨ã¯ãå ·ä½çã«ã¯ä»¥ä¸ã®ãã®ãããããã¾ãã æ¯è¼æ¼ç®ORlikeleft outer joinunionãµãã¯ã¨ãªexists ActiveRecordã§ãããã®ã¯ã¨ãªãçµã¿ç«ã¦ãå ´åãã©ããã¦ãç¾ãããªãï¼SQLæååãã¹ã£ããæ¸ãã¦ãã¾ããããªï¼æ¸ãæ¹ã¨ãªã£ã¦ãã¾ããã¡ã§ãã ãã®å¦çãç¾ããæ¸ãããã«ã¯ãActiveRecordã ãã®æ©è½ã§ã¯è¶³ãããActiveRecordãå é¨ã§ä½¿ã£ã¦ããArelã¨ããã©ã¤ãã©ãªã使ãå¿ è¦ãã§ã¦ãã¾ãã ä»åã¯ãArelã使ã£ã¦è¯éºã«SQLã¯
ActiveRecordï¼Rails3ã ã¨ActiveModelï¼ã¯ãèªåèªèº«ï¼ãªãã¸ã§ã¯ãï¼ã®ããããã£ã夿´ããããã©ãããã¾ãã©ã®ããããã£ãã©ã®ããã«å¤æ´ãããã®ããªã©ãåå¾ããæ©è½ãåãã£ã¦ãã¾ãã 管çç»é¢ã§æä½ãã°ãªã©ãå®è£ ããæã«å½¹ç«ã¡ããã§ãã 夿´ç¡ãï¼ @user = User.find_by_email("old@exmaple.com") @user.changed? # => false @user.changes # => {} @user = User.find_by_email("old@exmaple.com") @user.email = "new@exmaple.com" @user.changed? # => true @user.changes # => {"email"=>["old@exmaple.com", "new@exmaple.com
Railsã®ã¢ãã«éã®ãªã¬ã¼ã·ã§ã³ã®ã¡ã½ããã«ã¯ãå¤ãã®ãªãã·ã§ã³ãããã 仿¥ã¯ããããã使ã£ã¦ã§ãããã¨ãã¾ã¨ãã¦ããããã ãªã¬ã¼ã·ã§ã³ã®ãªãã·ã§ã³ã§ã§ãããã¨ä¸è¦§ 1. ããªã¢ã¼ãã£ãã¯é¢é£ã®å®ç¾© 2. ããªã¢ã¼ãã£ãã¯é¢é£ãå®ç¾©ãããã¢ãã«ã¨ä»ã®ã¢ãã«ã®é¢é£ã®å®ç¾© 3. 親ã¢ãã«ã«åã¢ãã«ãä¾åããããã«ãã 4. 親ã¢ãã«ã®ãã©ã¤ããªã¼ãã¼ãè¨å®ãã 5. å¤é¨ãã¼ã®ã«ã©ã åãè¨å®ãã 6. ç´ã¥ãã¢ãã«ã®ã¤ã³ã¹ã¿ã³ã¹ãåå¾ããã¡ã½ããã®ååãè¨å®ãã 7. ç´ã¥ãã¢ãã«ã®objectã«å¯¾ãã¦validationãå®è¡ããªã 8. ï¼é層以ä¸é¢ãã¦ããã¢ãã«ã®ã¤ã³ã¹ã¿ã³ã¹ãåå¾ãã 9. 親ã¢ãã«ã®ãªãã¸ã§ã¯ããsaveãããã¨ãã¦ããloadããã¦ããåã¢ãã«ã®ãªãã¸ã§ã¯ãã®å¤æ´ã¯saveãããªãããã«ãã 10. ã²ã¨ã¤ã®ã¢ãã«(A)ããä»ã®ã¢ãã«ãéãã¦ãããä¸åº¦ã¢ãã«(
Rails 2.1ããã®æ©è½ã§ããmodelã¨æ¸ãã¾ããããActiveRecordæ´¾çã¯ã©ã¹ã®ãªãã¸ã§ã¯ãã¨ãããã¨ã§ããmodelãæ´æ°ããåã«ãã©ã®ã«ã©ã ã夿´ããããã夿´åã®å¤ã¯ä½ãç¥ããã¨ãã§ãã¾ãã ãããªã¡ã½ãããç¨æããã¦ãã¾ãã changed?夿´ããã¦ããã©ããã changed夿´ããã¦ããattributeåã®é åã changes夿´ããã¦ããattributeååã¨å¤ã®ããã·ã¥ãå¤ã¯å¤æ´åæ´å¾ã®å¤ãé åã§ã <attr>_changed?<attr>ã夿´ããã¦ãããã©ããã <attr>_was<attr>ã®å¤æ´åã®å¤ãååããã¦ãªãã£ããå ã®å¤ã <attr>_change<attr>ã®å¤æ´åå¾ã®å¤ã®é åã夿´ããã¦ãªãã£ããnilã <attr>_will_change!<attr>ã夿´ãããã¨ãæç¤ºããã¤ä½¿ããããããã <attr>ã¯ãä¾ãã°ti
Active Recordã®ããªãã¼ã·ã§ã³ã¨ã³ã¼ã«ããã¯(Active Record Validations and Callbacks) â ãã®ã¬ã¤ãã§ã¯ãActive Record ãªãã¸ã§ã¯ãã®ã©ã¤ããµã¤ã¯ã«ã¸ã®ããã¯ã®æãæ¹ãæãã¾ãã ãã¼ã¿ãã¼ã¹ã«ä¿åãããåã«ãªãã¸ã§ã¯ãã®ç¶æ ãæ¤è¨¼ãããæ¹æ³ã¨ã ã©ã¤ããµã¤ã¯ã«ã®ç¹å®ã®æç¹ã§ã«ã¹ã¿ã æä½ãå®è¡ããæ¹æ³ãå¦ã¹ãã§ãããã ãã®ã¬ã¤ããèªãã§ãæç¤ºãããæ¦å¿µã試ããå¾ã以ä¸ã®ãã¨ãåºæ¥ãããã«ãªã£ã¦ãããã¨ãæã¿ã¾ãï¼ Active Record ã®ãªãã¸ã§ã¯ãã®ã©ã¤ããµã¤ã¯ã«ã®çè§£ã çµã¿è¾¼ã¿ã® Active Record ã®ããªãã¼ã·ã§ã³ãã«ãã®ä½¿ç¨ã ã«ã¹ã¿ã ããªãã¼ã·ã§ã³ã¡ã½ããã®ä½æã ããªãã¼ã·ã§ã³ã®ããã»ã¹ã«ãã£ã¦çæãããã¨ã©ã¼ã¡ãã»ã¼ã¸ã®åä½ã ãªãã¸ã§ã¯ãã®ã©ã¤ããµã¤ã¯ã«å ã®ã¤ãã³ãã«å¿çããã³ã¼ã«
ãªãªã¼ã¹ãé害æ å ±ãªã©ã®ãµã¼ãã¹ã®ãç¥ãã
ææ°ã®äººæ°ã¨ã³ããªã¼ã®é ä¿¡
å¦çãå®è¡ä¸ã§ã
j次ã®ããã¯ãã¼ã¯
kåã®ããã¯ãã¼ã¯
lãã¨ã§èªã
eã³ã¡ã³ãä¸è¦§ãéã
oãã¼ã¸ãéã
{{#tags}}- {{label}}
{{/tags}}