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Diffstat (limited to 'railties/guides/source/active_record_querying.textile')
| -rw-r--r-- | railties/guides/source/active_record_querying.textile | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/railties/guides/source/active_record_querying.textile b/railties/guides/source/active_record_querying.textile index 7a853db813..96f91cfef6 100644 --- a/railties/guides/source/active_record_querying.textile +++ b/railties/guides/source/active_record_querying.textile @@ -1042,20 +1042,26 @@ INSERT INTO clients (created_at, first_name, locked, orders_count, updated_at) V COMMIT </sql> -+first_or_create+ returns either the record that already existed or the new record. In our case, we didn't already have a client named Andy so the record was created an returned. ++first_or_create+ returns either the record that already exists or the new record. In our case, we didn't already have a client named Andy so the record is created and returned. The new record might not be saved to the database; that depends on whether validations passed or not (just like +create+). It's also worth noting that +first_or_create+ takes into account the arguments of the +where+ method. In the example above we didn't explicitly pass a +:first_name => 'Andy'+ argument to +first_or_create+. However, that was used when creating the new record because it was already passed before to the +where+ method. -NOTE: On previous versions of Rails you could do a similar thing with the +find_or_create_by+ method. Following our example, you could also run something like +Client.find_or_create_by_first_name(:first_name => "Andy", :locked => false)+. This method still works, but it's encouraged to use +first_or_create+ because it's more explicit on what arguments are used to _find_ the record and what arguments are used to _create_ it, resulting in less confusion overall. +You can do the same with the +find_or_create_by+ method: + +<ruby> +Client.find_or_create_by_first_name(:first_name => "Andy", :locked => false) +</ruby> + +This method still works, but it's encouraged to use +first_or_create+ because it's more explicit on which arguments are used to _find_ the record and which are used to _create_, resulting in less confusion overall. h4. +first_or_create!+ You can also use +first_or_create!+ to raise an exception if the new record is invalid. Validations are not covered on this guide, but let's assume for a moment that you temporarily add <ruby> - validates :orders_count, :presence => true +validates :orders_count, :presence => true </ruby> to your +Client+ model. If you try to create a new +Client+ without passing an +orders_count+, the record will be invalid and an exception will be raised: @@ -1065,14 +1071,12 @@ Client.where(:first_name => 'Andy').first_or_create!(:locked => false) # => ActiveRecord::RecordInvalid: Validation failed: Orders count can't be blank </ruby> -NOTE: Be sure to check the extensive *Active Record Validations and Callbacks Guide* for more information about validations. +h4. +first_or_initialize+ -h4. +first_or_new+ - -The +first_or_new+ method will work just like +first_or_create+ but it will not call +create+ but +new+. This means that a new model instance will be created in memory but won't be saved to the database. Continuing with the +first_or_create+ example, we now want the client named 'Nick': +The +first_or_initialize+ method will work just like +first_or_create+ but it will not call +create+ but +new+. This means that a new model instance will be created in memory but won't be saved to the database. Continuing with the +first_or_create+ example, we now want the client named 'Nick': <ruby> -nick = Client.where(:first_name => 'Nick').first_or_new(:locked => false) +nick = Client.where(:first_name => 'Nick').first_or_initialize(:locked => false) # => <Client id: nil, first_name: "Nick", orders_count: 0, locked: false, created_at: "2011-08-30 06:09:27", updated_at: "2011-08-30 06:09:27"> nick.persisted? @@ -1095,8 +1099,6 @@ nick.save # => true </ruby> -Just like you can use *+build+* instead of *+new+*, you can use *+first_or_build+* instead of *+first_or_new+*. - h3. Finding by SQL If you'd like to use your own SQL to find records in a table you can use +find_by_sql+. The +find_by_sql+ method will return an array of objects even if the underlying query returns just a single record. For example you could run this query: @@ -1246,12 +1248,3 @@ Client.sum("orders_count") </ruby> For options, please see the parent section, "Calculations":#calculations. - -h3. Changelog - -* June 26 2011: Added documentation for the +scoped+, +unscoped+ and +default+ methods. "Ryan Bigg":credits.html#radar -* December 23 2010: Add documentation for the +scope+ method. "Ryan Bigg":credits.html#radar -* April 7, 2010: Fixed document to validate XHTML 1.0 Strict. "Jaime Iniesta":http://jaimeiniesta.com -* February 3, 2010: Update to Rails 3 by "James Miller":credits.html#bensie -* February 7, 2009: Second version by "Pratik":credits.html#lifo -* December 29 2008: Initial version by "Ryan Bigg":credits.html#radar |