diff options
Diffstat (limited to 'railties/guides/source')
| -rw-r--r-- | railties/guides/source/active_record_querying.textile | 21 | ||||
| -rw-r--r-- | railties/guides/source/configuring.textile | 2 | ||||
| -rw-r--r-- | railties/guides/source/form_helpers.textile | 2 |
3 files changed, 21 insertions, 4 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index 073f7c143d..352f23dc01 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -1148,11 +1148,26 @@ Client.connection.select_all("SELECT * FROM clients WHERE id = '1'") 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. +<tt>pluck</tt> can be used to query a single column from the underlying table of a model. It accepts a column name as argument and returns an array of values of the specified column with the 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 +Client.where(:active => true).pluck(:id) +# SELECT id FROM clients WHERE active = 1 + +Client.uniq.pluck(:role) +# SELECT DISTINCT role FROM clients +</ruby> + ++pluck+ makes it possible to replace code like + +<ruby> +Client.select(:id).map { |c| c.id } +</ruby> + +with + +<ruby> +Client.pluck(:id) </ruby> h3. Existence of Objects diff --git a/railties/guides/source/configuring.textile b/railties/guides/source/configuring.textile index d91011c370..8e65dbccbb 100644 --- a/railties/guides/source/configuring.textile +++ b/railties/guides/source/configuring.textile @@ -268,6 +268,8 @@ h4. Configuring Active Record * +config.active_record.identity_map+ controls whether the identity map is enabled, and is false by default. +* +config.active_record.auto_explain_threshold_in_seconds+ configures the threshold for automatic EXPLAINs (+nil+ disables this feature). Queries exceeding the threshold get their query plan logged. Default is 0.5 in development mode. + The MySQL adapter adds one additional configuration option: * +ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans+ controls whether Active Record will consider all +tinyint(1)+ columns in a MySQL database to be booleans and is true by default. diff --git a/railties/guides/source/form_helpers.textile b/railties/guides/source/form_helpers.textile index 821bb305f6..64eb2d8f36 100644 --- a/railties/guides/source/form_helpers.textile +++ b/railties/guides/source/form_helpers.textile @@ -229,7 +229,7 @@ The corresponding view +app/views/articles/new.html.erb+ using +form_for+ looks There are a few things to note here: # +@article+ is the actual object being edited. -# There is a single hash of options. Routing options are passed in the +:url+ hash, HTML options are passed in the +:html+ hash. +# There is a single hash of options. Routing options are passed in the +:url+ hash, HTML options are passed in the +:html+ hash. Also you can provide a +:namespace+ option for your form to ensure uniqueness of id attributes on form elements. The namespace attribute will be prefixed with underscore on the generated HTML id. # The +form_for+ method yields a *form builder* object (the +f+ variable). # Methods to create form controls are called *on* the form builder object +f+ |