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| author | Jon Leighton <j@jonathanleighton.com> | 2011-11-30 01:41:09 -0800 |
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| committer | Jon Leighton <j@jonathanleighton.com> | 2011-11-30 01:41:09 -0800 |
| commit | 271308cb9617b86cd4de20b629be504b48aea537 (patch) | |
| tree | d713dd695abdcb09f1c191f1844166a27bf8ba38 /railties/guides/source/active_record_querying.textile | |
| parent | 38ab982cfff98570b5f12933cff489364845789c (diff) | |
| parent | a382d60f6abc94b6a965525872f858e48abc00de (diff) | |
| download | rails-271308cb9617b86cd4de20b629be504b48aea537.tar.gz rails-271308cb9617b86cd4de20b629be504b48aea537.tar.bz2 rails-271308cb9617b86cd4de20b629be504b48aea537.zip | |
Merge pull request #1915 from bogdan/active_record_map
ActiveRecord::Base.map method for direct select by single column
Diffstat (limited to 'railties/guides/source/active_record_querying.textile')
| -rw-r--r-- | railties/guides/source/active_record_querying.textile | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index c4724f182e..073f7c143d 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -1146,6 +1146,15 @@ h3. +select_all+ Client.connection.select_all("SELECT * FROM clients WHERE id = '1'") </ruby> +h3. +pluck+ + +<tt>pluck</tt> can be used to query single column from table under model. It accepts column name as argument and returns Array of values of the specified column with corresponding data type. + +<ruby> +Client.where(:active => true).pluck(:id) # SELECT id FROM clients WHERE clients.active +Client.uniq.pluck(:role) # SELECT DISTINCT role FROM clients +</ruby> + h3. Existence of Objects If you simply want to check for the existence of the object there's a method called +exists?+. This method will query the database using the same query as +find+, but instead of returning an object or collection of objects it will return either +true+ or +false+. |